## 2005 JGR-Space Physics Papers making use of ACE Data in their Investigations. No ACE team members on author list.

### (78 Papers)

 Variations of polar cap index in response to solar wind changes and magnetospheric substorms Huang C.-S. (2005), Variations of polar cap index in response to solar wind changes and magnetospheric substorms, J. Geophys. Res., 110, A01203, doi:10.1029/2004JA010616.  2005-01-08 Abstract: The polar cap (PC) index is used to measure the geomagnetic activity over the polar caps. Changes in the solar wind are able to cause disturbances in the magnetospheric-ionospheric currents, which in turn cause variations in the PC index. In order to understand how different processes in the solar wind and magnetosphere influence the PC index, it is necessary to separate the effects of solar wind pressure impulses, interplanetary magnetic field (IMF) reorientations, and magnetospheric substorms. We study the variations of the PC index under different solar wind conditions and during substorms and present case analyses and statistical results. The main conclusions are as follows. A solar wind pressure impulse alone, without IMF southward turning or substorm, is to cause a negative spike of ∼1 in the PC index within a time interval of 2–6 min and a subsequent increase to a positive value of ∼1 within 30 min. The PC index enhances significantly after the IMF turns southward, and the increase of the PC index is 3–5 in most cases and can be as large as 8–9. When a solar wind pressure impulse occurs with a simultaneous southward turning of the IMF, the large increase of the PC index is mainly a response to the southward IMF but not to the solar wind pressure impulse. Magnetospheric substorms have significant effects on the PC index. The response of the PC index to substorms is an increase of 2–4 in most cases and can reach 6 or larger. The effects of IMF southward turnings and substorms on the PC index are much stronger than that of solar wind pressure impulses. On average, the increases of the PC index caused by solar wind pressure impulses, substorm onsets, and IMF southward turnings are 0.8, 3.2, and 3.6, respectively.  Copyright 2005 by the American Geophysical Union. Necessary conditions for geosynchronous magnetopause crossings Suvorova A., A. Dmitriev, J.-K. Chao, M. Thomsen, Y.-H. Yang (2005), Necessary conditions for geosynchronous magnetopause crossings, J. Geophys. Res., 110, A01206, doi:10.1029/2003JA010079.  2005-01-14 Abstract: The International Solar Terrestrial Physics database of the magnetic measurements on GOES and plasma measurements on Los Alamos National Laboratory (LANL) geosynchronous satellites is used for selection of 169 case events containing 638 geosynchronous magnetopause crossings (GMCs) in 1995 to 2001. The GMCs and magnetosheath intervals associated with them are identified using advanced methods that take into account (1) strong deviation of the magnetic field measured by GOES from the magnetospheric field, (2) high correlation between the GOES magnetic field and interplanetary magnetic field (IMF), and (3) substantial increase of the midenergy ion and electron fluxes measured by LANL. Accurate determination of the upstream solar wind conditions for the GMCs is performed using correlation of geomagnetic activity (Dst (SYM-H) index) with the upstream solar wind pressure. The location of the GMCs and associated upstream solar wind conditions are ordered in an aberrated GSM coordinate system (aGSM) with X-axis directed along the solar wind flow. In the selected data set of GMCs the solar wind total pressure Psw varies up to 100 nPa and the southward IMF Bz reaches 60 nT. We study the conditions necessary for geosynchronous magnetopause crossings using scatterplots of the GMCs in the coordinate space of Psw versus Bz. In such a representation the upstream solar wind conditions show a sharp envelope boundary beyond which no GMCs are observed. The boundary has two straight horizontal branches where Bz does not influence the magnetopause location. The first branch is located in the range of Psw = 21 nPa for large positive Bz and is associated with a regime of pressure balance. The second branch asymptotically approaches the range of Psw = 4.8 nPa under strong negative Bz, and it is associated with a regime in which the Bz influence saturates. The intermediate region of the boundary ranges from moderate negative to moderate positive IMF Bz and can be well approximated by a hyperbolic tangent function. We interpret the envelope boundary as a range of necessary upstream solar wind conditions required for the magnetopause to reach geosynchronous orbit at its closest approach to the Earth (its “perigee” location).  Copyright 2005 by the American Geophysical Union. Formation and motion of a transpolar arc in response to dayside and nightside reconnection Milan S. E., B. Hubert, A. Grocott (2005), Formation and motion of a transpolar arc in response to dayside and nightside reconnection, J. Geophys. Res., 110, A01212, doi:10.1029/2004JA010835.  2005-01-19 Abstract: We trace the formation and subsequent motion of a transpolar arc in response to dayside and nightside reconnection. Both high- and low-latitude dayside reconnection are observed, as well as periods of substorm and nonsubstorm nightside reconnection, during the 7-hour interval of interest on 19 January 2002. We speculate that the arc is formed by a burst of nonsubstorm nightside reconnection and that its subsequent motion is controlled predominantly by the rate of dayside high-latitude reconnection, siphoning open flux from the dusk sector polar cap to the dawn sector. The observations allow us to quantify the rates of reconnection: on the nightside, 35 and 100 kV during nonsubstorm- and substorm-related bursts, respectively; on the dayside, 30 and 100 kV for high- and low-latitude reconnection. The latter values give effective merging line lengths of 1 and 5.5 R E for northward and southward interplanetary magnetic field, respectively. We suggest that transpolar arc motion will be controlled not only by the B y component of the IMF but also by the relative magnitude of the B z component, when ∣ B y ∣ > B z motion will be dawnward for B y < 0 nT and duskward for B y > 0 nT; however, when B z > ∣ B y ∣, we expect that the arc will move toward the noon-midnight meridian of the polar cap.  Copyright 2005 by the American Geophysical Union. Characteristic magnetic field and speed properties of interplanetary coronal mass ejections and their sheath regions Owens M. J., P. J. Cargill, C. Pagel, G. L. Siscoe, N. U. Crooker (2005), Characteristic magnetic field and speed properties of interplanetary coronal mass ejections and their sheath regions, J. Geophys. Res., 110, A01105, doi:10.1029/2004JA010814.  2005-01-20 Abstract: Prediction of the solar wind conditions in near-Earth space, arising from both quasi-steady and transient structures, is essential for space weather forecasting. To achieve forecast lead times of a day or more, such predictions must be made on the basis of remote solar observations. A number of empirical prediction schemes have been proposed to forecast the transit time and speed of coronal mass ejections (CMEs) at 1 AU. However, the current lack of magnetic field measurements in the corona severely limits our ability to forecast the 1 AU magnetic field strengths resulting from interplanetary CMEs (ICMEs). In this study we investigate the relation between the characteristic magnetic field strengths and speeds of both magnetic cloud and noncloud ICMEs at 1 AU. Correlation between field and speed is found to be significant only in the sheath region ahead of magnetic clouds, not within the clouds themselves. The lack of such a relation in the sheaths ahead of noncloud ICMEs is consistent with such ICMEs being skimming encounters of magnetic clouds, though other explanations are also put forward. Linear fits to the radial speed profiles of ejecta reveal that faster-traveling ICMEs are also expanding more at 1 AU. We combine these empirical relations to form a prediction scheme for the magnetic field strength in the sheaths ahead of magnetic clouds and also suggest a method for predicting the radial speed profile through an ICME on the basis of upstream measurements.  Copyright 2005 by the American Geophysical Union. Interplanetary consequences caused by the extremely intense solar activity during October–November 2003 Tokumaru M., M. Kojima, K. Fujiki, M. Yamashita, D. Baba (2005), Interplanetary consequences caused by the extremely intense solar activity during October–November 2003, J. Geophys. Res., 110, A01109, doi:10.1029/2004JA010656.  2005-01-28 Abstract: We report interplanetary scintillation (IPS) measurements made by the 327 MHz four-station system of the Solar-Terrestrial Environment Laboratory of Nagoya University, during 21 October to 8 November 2003. In this period, solar activity increased greatly owing to the appearance of huge eruptive sunspots on the solar disk. Interplanetary (IP) disturbance events traveling from the Sun beyond the Earth's orbit have been detected clearly from our IPS observations in association with most of the major eruptive events that occurred on the Sun during that period. A possible link between solar/IPS events and near-Earth (IP shock) events in that same period was investigated in this study. As a result, an IP counterpart was identified by our IPS observations for all of the shock events which occurred during the period, and the link to solar events was established unambiguously for the majority of shock events on the basis of the identification of their IP counterparts. Among the IP disturbance events, the most prominent one occurred between 28 and 29 October 2003, and it is considered as an IP counterpart to the 28 October X17 flare event. Our IPS data revealed a complex feature of this IP disturbance and demonstrated that the global distribution of the solar wind density turbulence settled into a rather quiescent condition after the X17 event except between 2 and 4 November 2003, despite the occurrence of marked solar activities. This is in clear contrast to the fact that enhancements of the turbulence level had taken place frequently before the event. The lack of marked g-value enhancements for those events is considered partly due to the intrinsic effect related to a change in the global distribution of the solar wind turbulence and partly due to artificial effects inherent in our IPS observations. The radial expansion of the IP disturbance was tracked successfully by consecutive IPS observations during the period between 2 and 4 November in association with the 2 November X8.3 flare event. The movement of this IP disturbance inferred from IPS data was found to be generally consistent with the average transit speed of the IP shock associated with the X8.3 event, although some deceleration of the IP disturbance may have taken place.  Copyright 2005 by the American Geophysical Union. Low-energy neutral atom signatures of magnetopause motion in response to southward B z Collier M. R., T. E. Moore, M.-C. Fok, B. Pilkerton, S. Boardsen, H. Khan (2005), Low-energy neutral atom signatures of magnetopause motion in response to southward B z, J. Geophys. Res., 110, A02102, doi:10.1029/2004JA010626.  2005-02-03 Abstract: We report an event observed by the Low-Energy Neutral Atom (LENA) imager on 18 April 2001, in which enhanced neutral atom emission was observed coming from the direction of the Sun and from the general direction of the subsolar magnetopause. The enhanced neutral atom emission is shown to be primarily a result of increased solar wind charge exchange with the Earth's hydrogen exosphere, that is, enhanced neutral solar wind formation, occurring in conjunction with a southward turning of the interplanetary magnetic field (IMF) which moves the magnetopause closer to the Earth. It is shown that the neutral atom flux under compressed magnetopause conditions is extremely sensitive to changes in the IMF north-south component.  Copyright 2005 by the American Geophysical Union. Origins and variation of terrestrial energetic neutral atoms outflow Wilson G. R., T. E. Moore (2005), Origins and variation of terrestrial energetic neutral atoms outflow, J. Geophys. Res., 110, A02207, doi:10.1029/2003JA010356.  2005-02-11 Abstract: Analysis of ENA data from the LENA instrument on the IMAGE spacecraft shows that the terrestrial atmosphere is a copious emitter of energetic neutral atoms (<300 eV) under all conditions. When activity is low, the observed emissions are concentrated close to the Earth and are presumed to be the high-energy tail of the warm oxygen geocorona, with energies <2 eV. When activity increases, the relative abundance of the higher-energy neutrals increases, and the emissions can be seen farther from the Earth. Because of the close correlation between the postperigee ENA flux (fluxes seen 1–2 hours after spacecraft perigee) and Ap and the fact that the postperigee fluxes are seen when no magnetic storm is in progress we conclude that many of the emitted ENA come from the auroral zone and are produced by energized ionospheric ions rather than by precipitating energetic ions. In more spectacular events, such as the Bastille Day storm event (14–16 July 2000), oxygen neutral emissions produced by precipitation of keV ring current oxygen ions can also make an important contribution to the total neutral emission. We conclude that diurnal variation in ENA emissions is a winter hemisphere feature that is absent in the summer hemisphere. As activity increases, the altitude range of the auroral oval ENA emission region increases.  Copyright 2005 by the American Geophysical Union. High-altitude cusp flow dependence on IMF orientation: A 3-year Cluster statistical study Lavraud B., A. Fedorov, E. Budnik, M. F. Thomsen, A. Grigoriev, P. J. Cargill, M. W. Dunlop, H. Rème, I. Dandouras, A. Balogh (2005), High-altitude cusp flow dependence on IMF orientation: A 3-year Cluster statistical study, J. Geophys. Res., 110, A02209, doi:10.1029/2004JA010804.  2005-02-15 Abstract: We report on the statistical properties of the plasma flows measured by the Cluster spacecraft in the high-altitude cusp region of the Northern Hemisphere as a function of the interplanetary magnetic field (IMF) orientation, with selected clock angle intervals. The technique uses a magnetic field model, taking into account the actual solar wind conditions and level of geomagnetic activity, in order to model the magnetopause and cusp displacements as a function of these conditions. The distributions of the magnetic field vector show a clear consistency with the IMF clock angle intervals chosen and demonstrate that the technique used here fixes the positions of the cusp boundaries adequately. The antisunward convection observed in the exterior cusp suggests that this region is statistically quite convective under southward IMF, while for northward IMF the region appears more stagnant. The presence of large parallel (downward) flows at the equatorward edge of the cusp shows that plasma penetration occurs preferentially at the dayside low-latitude magnetopause for southward IMF conditions; in contrast, under northward IMF the results are suggestive of plasma penetration from the poleward edge of the cusp, combined with a substantial sunward convection, but no flows are observed at all at the dayside boundary with the plasma sheet. The comparison of the measured flow speed with the Alfvén speed suggests that the magnetosheath adjacent to the external boundary is more sub-Alfvénic, even for high magnetic latitudes, under northward IMF than under southward IMF. This result is consistent with the preference for the plasma depletion layer to develop under such conditions. The transverse plasma convection in the exterior cusp appears to be controlled by the IMF B Y component as well; for dawnward (duskward) IMF orientations the convection is preferentially directed toward dusk (dawn). These results are interpreted as strong arguments in favor of the cusp being structured, at large scales, by the occurrence of magnetic reconnection at the high-latitude magnetopause for northward IMF and at the low-latitude magnetopause for southward IMF.  Copyright 2005 by the American Geophysical Union. Solar wind spatial scales in and comparisons of hourly Wind and ACE plasma and magnetic field data King J. H., N. E. Papitashvili (2005), Solar wind spatial scales in and comparisons of hourly Wind and ACE plasma and magnetic field data, J. Geophys. Res., 110, A02104, doi:10.1029/2004JA010649.  2005-02-16 Abstract: Hourly averaged interplanetary magnetic field (IMF) and plasma data from the Advanced Composition Explorer (ACE) and Wind spacecraft, generated from 1 to 4 min resolution data time-shifted to Earth have been analyzed for systematic and random differences. ACE moments-based proton densities are larger than Wind/Solar Wind Experiment (SWE) fits-based densities by up to 18%, depending on solar wind speed. ACE temperatures are less than Wind/SWE temperatures by up to ∼25%. ACE densities and temperatures were normalized to equivalent Wind values in National Space Science Data Center's creation of the OMNI 2 data set that contains 1963–2004 solar wind field and plasma data and other data. For times of ACE-Wind transverse separations <60 R E, random differences between Wind values and normalized ACE values are ∼0.2 nT for ∣ B ∣, ∼0.45 nT for IMF Cartesian components, ∼5 km/s for flow speed, and ∼15 and ∼30% for proton densities and temperatures. These differences grow as a function of transverse separation more rapidly for IMF parameters than for plasma parameters. Autocorrelation analyses show that spatial scales become progressively shorter for the parameter sequence: flow speed, IMF magnitude, plasma density and temperature, IMF X and Y components, and IMF Z component. IMF variations have shorter scales at solar quiet times than at solar active times, while plasma variations show no equivalent solar cycle dependence.  Copyright 2005 by the American Geophysical Union. Dynamic Harris current sheet thickness from Cluster current density and plasma measurements Thompson S. M., M. G. Kivelson, K. K. Khurana, R. L. McPherron, J. M. Weygand, A. Balogh, H. Réme, L. M. Kistler (2005), Dynamic Harris current sheet thickness from Cluster current density and plasma measurements, J. Geophys. Res., 110, A02212, doi:10.1029/2004JA010714.  2005-02-19 Abstract: We use the first accurate measurements of current densities in the plasma sheet to calculate the half-thickness and position of the current sheet as a function of time. Our technique assumes a Harris current sheet model, which is parameterized by lobe magnetic field B 0, current sheet half-thickness h, and current sheet position z 0. Cluster measurements of magnetic field, current density, and plasma pressure are used to infer the three parameters as a function of time. We find that most long timescale (6–12 hours) current sheet crossings observed by Cluster cannot be described by a static Harris current sheet with a single set of parameters B 0, h, and z 0. Noting the presence of high-frequency fluctuations that appear to be superimposed on lower frequency variations, we average over running 6-min intervals and use the smoothed data to infer the parameters h (t) and z 0 (t), constrained by the pressure balance lobe magnetic field B 0 (t). Whereas this approach has been used in previous studies, the spatial gradients now provided by the Cluster magnetometers were unavailable or not well constrained in earlier studies. We place the calculated half-thicknesses in a magnetospheric context by examining the change in thickness with substorm phase for three case study events and 21 events in a superposed epoch analysis. We find that the inferred half-thickness in many cases reflects the nominal changes experienced by the plasma sheet during substorms (i.e., thinning during growth phase, thickening following substorm onset). We conclude with an analysis of the relative contribution of ∂ B Z /∂ X to the cross-tail current density during substorms. We find that ∂ B Z /∂ X can contribute a significant portion of the cross-tail current around substorm onset.  Copyright 2005 by the American Geophysical Union. How good is the relationship of solar and interplanetary plasma parameters with geomagnetic storms? Kane R. P. (2005), How good is the relationship of solar and interplanetary plasma parameters with geomagnetic storms?, J. Geophys. Res., 110, A02213, doi:10.1029/2004JA010799.  2005-02-25 Abstract: Since the work of Snyder et al. (1963), who showed a possible link between interplanetary solar wind speed V and geomagnetic index Kp, such a relationship has been examined by many workers and found to be rather loose. In the present communication this relationship is rechecked for all data during 1973–2003. It was noted that moderate or strong geomagnetic storms occurred only when solar wind speed V was above ∼350 km/s. However, above this limit, the plots of Dst versus V showed a large scatter, and any value of V could be associated with any value of Dst in a wide range of a factor of ∼2, or any Dst value could be associated with any value of V in a wide range of a factor of ∼2, indicating a poor relationship between V and Dst. The scatter could be partly because not V but VB s (product of V and the southward component B s of interplanetary field B) is the appropriate variable relevant for Dst changes. This was checked. In the plot of Dst versus VB s it was noticed that the scatter was smaller and correlation better than that in the plot of Dst versus V. Since the relationship between V and Dst is poor, an estimate of V with some antecedence, as is done in a present-day prediction scheme ((Gonzalez et al., 2004) V estimated from the lateral extension speed of side halo coronal mass ejections (CMEs) and assuming V 2 proportional to Dst magnitudes) is not likely to give reliable estimates of Dst magnitudes. However, estimate of V could certainly be useful to estimate the time when the storm would hit the Earth but remembering that 15% of the halo CMEs may miss the Earth.  Copyright 2005 by the American Geophysical Union. Coupled response of the inner magnetosphere and ionosphere on 17 April 2002 Goldstein J., J. L. Burch, B. R. Sandel, S. B. Mende, P. C:son Brandt, M. R. Hairston (2005), Coupled response of the inner magnetosphere and ionosphere on 17 April 2002, J. Geophys. Res., 110, A03205, doi:10.1029/2004JA010712.  2005-03-04 Abstract: We present an observational study of the global dynamics of the plasmasphere, aurora, ring current, and subauroral ionosphere on 17 April 2002 during a substorm. Global observations by the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) and in situ observations by DMSP F13 provide a comprehensive view of the coupled response of the inner magnetosphere and ionosphere. At 1900 UT a substorm onset initiated a sunward convective impulse, which caused a ring current injection. The motion of this impulse past the plasmasphere caused ripples to propagate along the plasmapause, eastward and westward from premidnight magnetic local time (MLT). The motion of the ripples agrees exceptionally well with the motion of the aurora and the ring current, implying strong coupling. The westward moving ripple (on the duskside) participated in a two-phase plasmapause undulation effect. In the first phase (1915 UT to 1936 UT), a mild 0.4–0.5 R E bulge formed near 2000 MLT, probably caused by an E-field induced by local reduction of the magnetic field by the ring current pressure increase. In the second phase (1936 UT to 2037 UT) this mild bulge was removed by a subauroral polarization stream (SAPS) westward flow that stripped away the outer 1 R E of the duskside plasmasphere. The SAPS effect was observed in the ionosphere by DMSP between about 1930 UT and 2000 UT and is evident in vector E-fields inferred from plasmapause motion. All the observations of this event suggest strong coupling among the plasma populations of the magnetosphere-ionosphere system. This event represents the first identification of the directly observed global plasmaspheric effects of a substorm-driven impulse, the SAPS flow channel, and the ring-current magnetic field reduction.  Copyright 2005 by the American Geophysical Union. Some characteristics of intense geomagnetic storms and their energy budget Vichare G., S. Alex, G. S. Lakhina (2005), Some characteristics of intense geomagnetic storms and their energy budget, J. Geophys. Res., 110, A03204, doi:10.1029/2004JA010418.  2005-03-04 Abstract: The present study analyses nine intense geomagnetic storms (∣ Dst ∣ > 175 nT) with the aid of ACE satellite measurements and ground magnetic field values at Alibag Magnetic Observatory. The study confirms the crucial role of southward IMF in triggering the storm main phase as well as controlling the magnitude of the storm. The main phase interval shows clear dependence on the duration of southward IMF. An attempt is made to identify the multipeak signature in the ring current energy injection rate during main phase of the storm. In order to quantify the energy budget of magnetic storms, the present paper computes the solar wind energies, magnetospheric coupling energies, auroral and Joule heating energies, and the ring current energies for each storm under examination. Computation of the solar wind- magnetosphere coupling function considers the variation of the size of the magnetosphere by using the measured solar wind ram pressure. During the main phase of the storm, the solar wind kinetic energy ranges from 9  Copyright 2005 by the American Geophysical Union. Solar zenith angle and merging electric field control of field-aligned currents: A statistical study of the Southern Hemisphere Wang H., H. Lühr, S. Y. Ma (2005), Solar zenith angle and merging electric field control of field-aligned currents: A statistical study of the Southern Hemisphere, J. Geophys. Res., 110, A03306, doi:10.1029/2004JA010530.  2005-03-22 Abstract: High-resolution and precise vector magnetic field measurements of the CHAMP satellite are used to investigate the field-aligned currents (FACs) in the southern polar ionosphere. The period considered comprises 2 years, providing a double coverage of the seasons and about a six-fold coverage of all local times. From more than 11,000 polar passes the average spatial pattern of FACs in the polar ionosphere is derived. The response of features like intensity and positions of large-scale field-aligned currents to normal (when merging electric field is less than 2 mV/m) and disturbed (when merging electric field is greater than 2 mV/m) conditions in the Southern Hemisphere are investigated. The influence of the solar illumination-induced conductivity on the morphology features of field-aligned currents during normal conditions are also studied. It follows from this analysis that the intensity of field-aligned currents changes with the merging electric field at all MLT sectors but with the solar radiation-induced conductivity only at the dayside. Furthermore, a linear relation between the conductivity and the peak FAC density exists, which implies that the dayside FAC densities are directly controlled by the amount of solar radiation. Solar elevation does not affect the nightside FAC density. On the dayside a systematic difference of the footprint latitude between sunlit and dark conditions emerges. Under dark conditions the auroral region retreats about 2° equatorward. On the basis of the above results, we may suggest that the sources of Birkeland currents on the zdayside behave like a voltage source, while on the nightside the response is possibly like a current source.  Copyright 2005 by the American Geophysical Union. Magnetotail response to prolonged southward IMF B z intervals: Loading, unloading, and continuous magnetospheric dissipation Tanskanen E. I., J. A. Slavin, D. H. Fairfield, D. G. Sibeck, J. Gjerloev, T. Mukai, A. Ieda, T. Nagai (2005), Magnetotail response to prolonged southward IMF B z intervals: Loading, unloading, and continuous magnetospheric dissipation, J. Geophys. Res., 110, A03216, doi:10.1029/2004JA010561.  2005-03-22 Abstract: The response of the Earth's magnetotail to prolonged southward interplanetary magnetic field (IMF) has been determined for the three Geotail magnetotail seasons from November to April, 1999–2002. We examine the total magnetotail pressure P T,tail = B 2 /2μ 0 + N i kT i because variations should be similar in this parameter in the lobes and in the plasma sheet. We found 13 events when IMF B z remained southward for 8 hours or longer and Geotail was located within the magnetotail farther than 10 R E downstream. All 13 events were subdivided into separate intervals characterized as (1) loading, if the tail total pressure increased more than 100%; (2) unloading, if the total pressure decreased by more than 50%; and (3) what we term here continuous magnetospheric dissipation (CMD), if the tail total pressure increased by less than 100% and/or decreased less than 50% during the entire mode interval. In total, 37 loading, 37 unloading, and 28 CMD events were found. The plasma sheet magnetic flux transfer rate, $\phi$ Earth ≈ v x ? B z, and plasma bulk velocity has been analyzed to determine the steadiness of the plasma sheet convection. Plasma sheet convection was found to be highly disturbed and intense plasma flows (BBFs and FBs) were observed during all convection states. However, the occurence rate and amplitude of plasma flows distinguish loading-unloading and continuous dissipation periods from each other. BBFs seem to be more numerous (135) but weaker (about 500 km/s) during continuous dissipation intervals compared with BBFs existing during unloading mode (61 and 660 km/s). Finally, it was found that CMD-type convection is more likely when the mean southward IMF B z > −5 nT, while loading-unloading is more likely when IMF B z < −5 nT.  Copyright 2005 by the American Geophysical Union. Multipoint observations of transient reconnection signatures in the cusp precipitation: A Cluster-IMAGE detailed case study Bosqued J. M., et al. (2005), Multipoint observations of transient reconnection signatures in the cusp precipitation: A Cluster-IMAGE detailed case study, J. Geophys. Res., 110, A03219, doi:10.1029/2004JA010621.  2005-03-29 Abstract: This paper uses 90 min of Cluster multipoint data at ∼5 R E altitude together with global dayside imaging data provided by the IMAGE-SI-12 instrument to analyze the northern cusp crossed on 14 July 2001, during a period of high solar wind pressure P sw and strongly duskward interplanetary magnetic field (IMF). Simultaneous observations reveal intense cusp activity in the postnoon sector, characterized by multiple, impulsive energy-dispersed ion injections, with a recurrence time of ∼8–10 min or less. Most of these transient signatures correspond one to one with repeated P sw enhancements. A multipoint analysis reveals that field-aligned current sheets associated with ion steps are moving predominantly westward with a velocity, up to ∼20 km/s, in agreement with a flux tube motion controlled by magnetic tension forces when IMF B y $\gg$ 0. These data are used to infer a source region located at ∼7–13 R E from Cluster, that is, on the dusk flank of the compressed magnetosphere, around 17–18 magnetic local time. We interpret these very dynamic and transient features as probable signatures of pulsed magnetic reconnection that is operating in a localized region of the magnetopause centered in the preferential antiparallel merging site. Our results suggest that the reconnection rate is not spontaneously self-varying but may be directly modulated by either upstream dynamic pressure P sw or changes in the IMF polarity.  Copyright 2005 by the American Geophysical Union. Kp forecast models Wing S., J. R. Johnson, J. Jen, C.-I. Meng, D. G. Sibeck, K. Bechtold, J. Freeman, K. Costello, M. Balikhin, K. Takahashi (2005), Kp forecast models, J. Geophys. Res., 110, A04203, doi:10.1029/2004JA010500.  2005-04-09 Abstract: Magnetically active times, e.g., Kp > 5, are notoriously difficult to predict, precisely the times when such predictions are crucial to the space weather users. Taking advantage of the routinely available solar wind measurements at Langrangian point (L1) and nowcast Kps, Kp forecast models based on neural networks were developed with the focus on improving the forecast for active times. To satisfy different needs and operational constraints, three models were developed: (1) a model that inputs nowcast Kp and solar wind parameters and predicts Kp 1 hour ahead; (2) a model with the same input as model 1 and predicts Kp 4 hour ahead; and (3) a model that inputs only solar wind parameters and predicts Kp 1 hour ahead (the exact prediction lead time depends on the solar wind speed and the location of the solar wind monitor). Extensive evaluations of these models and other major operational Kp forecast models show that while the new models can predict Kps more accurately for all activities, the most dramatic improvements occur for moderate and active times. Information dynamics analysis of Kp suggests that geospace is more dominated by internal dynamics near solar minimum than near solar maximum, when it is more directly driven by external inputs, namely solar wind and interplanetary magnetic field (IMF).  Copyright 2005 by the American Geophysical Union. Neutral composition effects on ionospheric storms at middle and low latitudes Liou K., P. T. Newell, B. J. Anderson, L. Zanetti, C.-I. Meng (2005), Neutral composition effects on ionospheric storms at middle and low latitudes, J. Geophys. Res., 110, A05309, doi:10.1029/2004JA010840.  2005-05-20 Abstract: The two-dimensional structure of thermospheric neutral composition, specifically, the atomic oxygen to molecular nitrogen column density ratio, [O/N 2], is studied during the 17–24 April 2002 geomagnetic storms to understand the cause of ionospheric storms in regions equatorward of the auroral oval on an instantaneous large scale. The [O/N 2] ratio is derived from the dayglow emission ratio of O I 1356  Copyright 2005 by the American Geophysical Union. Stagnant exterior cusp region as viewed by energetic electrons and ions: A statistical study using Cluster Research with Adaptive Particle Imaging Detectors (RAPID) data Zhang H., T. A. Fritz, Q.-G. Zong, P. W. Daly (2005), Stagnant exterior cusp region as viewed by energetic electrons and ions: A statistical study using Cluster Research with Adaptive Particle Imaging Detectors (RAPID) data, J. Geophys. Res., 110, A05211, doi:10.1029/2004JA010562.  2005-05-27 Abstract: We present statistical results based on the data set obtained by Cluster when these spacecraft were in the dayside cusp and magnetopause. Forty clearest stagnant exterior cusp (SEC) events have been selected from ∼150 cusp crossings from 1 January to 30 April 2001 and from 1 March to 30 April 2002. The identification of the SECs was made on the basis of the following criteria: high-density plasma (comparable to the sheath level) and small or stagnant plasma flow (V x < 60 km s −1). We found that energetic ions are observed in the high-latitude magnetospheric region for 32 SEC crossings (80%) and energetic electrons are observed on 9 of 40 events (22.5%). The SEC is found to lie predominantly within 1000–1300 magnetic local time (MLT); however, there are some cases where this region extends to both earlier and later MLTs. Twenty-nine SEC events (72.5%) have been found in association with depressed magnetic field. The angular difference between the interplanetary magnetic field (IMF) and local clock angles is a good criterion for 29 SEC events (72.5%). The particle spectra are characterized by a power law, and the power law index is found to be closely related to solar wind velocity. The spectra seem to be harder for higher solar wind velocity. We also found that the higher the solar wind velocity, the higher the ion flux in the SEC region. The magnetic shear angle is the difference between local B vector and IMF clock angle projected on the plane perpendicular to the shock normal. The larger the magnetic shear angle, the more turbulent the magnetic field in the SEC. The turbulence in the SEC region does not affect the power law index, but it is one of the factors controlling of the SEC region. Further, there is no clear relationship found between the power law index and IMF B z, Dst, or the magnetic shear angle.  Copyright 2005 by the American Geophysical Union. Enhanced solar wind geoeffectiveness after a sudden increase in dynamic pressure during southward IMF orientation Boudouridis A., E. Zesta, L. R. Lyons, P. C. Anderson, D. Lummerzheim (2005), Enhanced solar wind geoeffectiveness after a sudden increase in dynamic pressure during southward IMF orientation, J. Geophys. Res., 110, A05214, doi:10.1029/2004JA010704.  2005-05-27 Abstract: It is well known that a persistent southward Interplanetary Magnetic Field (IMF) produces increased geomagnetic activity. It has recently been shown that a sudden increase in solar wind pressure results in poleward expansion of the auroral oval and closing of the polar cap over a wide range of MLTs, and this effect is more pronounced under southward IMF orientation. We show that southward IMF conditions combined with high solar wind dynamic pressure immediately after a pressure front impact lead to enhanced coupling between the solar wind and the terrestrial magnetosphere, significantly increasing the geoeffectiveness of the solar wind. We evaluate geoeffectiveness by the coupling efficiency, defined as the ratio of the cross-polar-cap potential measured by Defense Meteorological Satellite Program (DMSP) spacecraft to the cross-magnetospheric potential calculated using solar wind parameters. We examine changes in the size of the polar cap and the coupling efficiency for a number of solar wind pressure enhancements under southward IMF configuration. We confirm the previously observed closing of the polar cap and show that there is a simultaneous increase of the coupling efficiency. This increase is measured for all cases, despite the fact that the magnetosphere is greatly compressed, and the increase is measured even when the solar wind electric field is reduced.  Copyright 2005 by the American Geophysical Union. Acceleration and transport of heavy ions at coronal mass ejection-driven shocks Li G., G. P. Zank, W. K. M. Rice (2005), Acceleration and transport of heavy ions at coronal mass ejection-driven shocks, J. Geophys. Res., 110, A06104, doi:10.1029/2004JA010600.  2005-06-24 Abstract: It is now widely accepted that large solar energetic particle (SEP) events are associated with coronal mass ejection (CME)-driven shocks. Here, particles are often accelerated to approximately MeV energies (and perhaps up to GeV energies) at shock waves driven by CMEs. In this paper, on the basis of our earlier work, we present a detailed model which calculates the acceleration of heavy ions at CME-driven shocks and their subsequent propagation in the interplanetary medium. The CME-driven shock is followed numerically using the two-dimensional ZEUS code. At the shock front and upstream of the shock, the coupled system of streaming protons and stimulated upstream turbulence (assuming the form of Alfvén waves) is considered and the diffusion coefficient of the energetic ions and the stimulated wave intensity is evaluated self-consistently. The particle diffusion coefficient is then used to determine the maximum momentum of energetic ions. The ion spectra at the shock front are obtained by adopting the steady-state solution of the transport equation. Across the shock front, the upstream turbulence is amplified and the particle diffusion coefficient is further decreased. Energetic particles in the downstream region convect with the solar wind, cool adiabatically, and diffuse. These effects are followed using a shell model. Particles diffuse ahead of the shock front, can escape and propagate in the interplanetary medium subject to pitch angle scattering. The transport of these particles is followed using a Monte-Carlo code. Two shocks, one strong and one weak, are considered. Time intensity profiles and particle spectra at various times are obtained for two groups of ions, corresponding to Fe and CNO particles. These results will be helpful on understanding in situ observations at 1 AU made by spacecraft such as ACE and Wind.  Copyright 2005 by the American Geophysical Union. AE index variability during corotating fast solar wind streams Diego P., M. Storini, M. Parisi, E. G. Cordaro (2005), AE index variability during corotating fast solar wind streams, J. Geophys. Res., 110, A06105, doi:10.1029/2004JA010715.  2005-06-24 Abstract: We examine the AE index variability while 12 corotating fast solar wind streams pass the Earth during the ascending phase of the ongoing solar activity cycle. We apply the Discrete Fourier Transform analysis to the associated interplanetary magnetic field (B) data and AE time series with ∼1 min resolution. Results show noticeable periodicities in the 1–10 hour range. Moreover, the B and AE periodicities in each event are well correlated. For this reason a direct relationship between interplanetary Alfvénic waves and AE oscillations is proposed while those streams pass the Earth.  Copyright 2005 by the American Geophysical Union. Computing the reconnection rate at the Earth's magnetopause using two spacecraft observations Fuselier S. A., K. J. Trattner, S. M. Petrinec, C. J. Owen, H. R  2005-06-24 Abstract: A new multispacecraft technique is introduced which, under some restrictive assumptions and conditions, provides a snapshot of the reconnection inflow velocity into the magnetosphere and an estimate of the distance from the spacecraft to the reconnection site. The two quantities are not obtained independent of one another and additional, independent information is needed to separate them. This new technique is applied to Cluster spacecraft observations at the Earth's magnetopause. Additional Cluster observations and observations from the IMAGE spacecraft are used as independent information to provide an estimate of the distance from the spacecraft to the reconnection site for the event. From this distance estimate and the new multispacecraft technique, it is concluded that component reconnection was probably occurring at the magnetopause and that the local inflow velocity was significantly less than 0.1 V A.  Copyright 2005 by the American Geophysical Union. On the relationships between double-onset substorm, pseudobreakup, and IMF variation: The 4 September 1999 event Cheng C.-C., C. T. Russell, G. D. Reeves, M. Connors, M. B. Moldwin (2005), On the relationships between double-onset substorm, pseudobreakup, and IMF variation: The 4 September 1999 event, J. Geophys. Res., 110, A07201, doi:10.1029/2004JA010778.  2005-07-02 Abstract: The relationships between double-onset substorm, pseudobreakup, and IMF variation were investigated with magnetic, auroral, and particle observations from space to the ground during 0200–0600 UT on 4 September 1999. There were five consecutive bursts of Pi2 pulsations on the ground during the time of interest. The onset time of ground Pi2s maps to the same variation sequence in the IMF structure seen propagating to the Earth in multiple satellite observations in the upstream region. The comparison of auroral and energetic particle data with IMF observations shows that a sequence of two double-onset substorms intervened by a pseudobreakup appears in two distinct cycles of southward IMF followed by a northward interval. For the first substorm, the first onset begins when the B y magnitude declines after the IMF turns southward for about 90 min, and the second onset occurs after northward turning of the IMF accompanied by an increasing B y magnitude. The pseudobreakup appears while the IMF turns southward and the B y magnitude slightly decreases. For the second substorm, the first onset commences while the IMF remains southward with a steady B y magnitude, and the second onset occurs after the IMF becomes strongly northward and the B y magnitude decreases instead. These observations can be explained with the two-neutral-point model. The first onset occurs when the IMF turns southward. Reconnection at the near-Earth neutral point first begins on closed field lines within the plasma sheet, and the second onset occurs when the IMF turns northward and reconnection at the distant neutral point ceases and reconnection at the near-Earth neutral point may reach the open flux of the tail lobes. In addition, a decrease in the B y magnitude may help reduce magnetotail convection and release all the built-up flux to allow the onset to commence after northward turning of the IMF. If the IMF remains southward, the reduction of magnetotail convection due to a decreasing B y would lead to a pseudobreakup instead. In contrast, an increasing B y magnitude would increase magnetotail convection and weaken magnetospheric substorm after the IMF turns northward. Consequently, for the occurrence of double-onset substorms and pseudobreakups, not only the first onset begins spontaneously during steady southward IMF and the second onset appears after northward turning of the IMF but the B y change also affects magnetotail convection which may evoke (or abate) the substorm-related activation while the IMF turns southward (or northward).  Copyright 2005 by the American Geophysical Union. Are sawtooth oscillations of energetic plasma particle fluxes caused by periodic substorms or driven by solar wind pressure enhancements? Huang C.-S., G. D. Reeves, G. Le, K. Yumoto (2005), Are sawtooth oscillations of energetic plasma particle fluxes caused by periodic substorms or driven by solar wind pressure enhancements?, J. Geophys. Res., 110, A07207, doi:10.1029/2005JA011018.  2005-07-07 Abstract: Energetic electron and proton fluxes measured by geosynchronous satellites often show sawtooth-like variations during magnetic storms. We examine whether the sawtooth oscillations and relevant magnetospheric-ionospheric disturbances are caused by periodic substorms or driven by a series of enhancements in the solar wind pressure. We show that there are significant differences between periodic substorms and solar wind-induced variations. The energetic fluxes at geosynchronous orbit may increase by orders of magnitude after each onset of periodic substorms and by 10–50% in response to a large solar wind pressure impulse. The sudden increases of the energetic fluxes during periodic substorms show significant time delays of 30–50 min at different longitudes/local times, indicating that the fluxes are injected on the nightside and then drift to the dayside. In contrast, the small flux increases caused by solar wind pressure enhancements occur almost simultaneously at all local times. The periodic substorms always have a strong spectrum peak at 2–3 hours, no matter whether the solar wind pressure and/or IMF have similar spectrum peaks. The nightside magnetospheric magnetic elevation angle shows a large (30–60  Copyright 2005 by the American Geophysical Union. Local time distribution of low and middle latitude ground magnetic disturbances at sawtooth injections of 18–19 April 2002 Kitamura K., H. Kawano, S. Ohtani, A. Yoshikawa, K. Yumoto (2005), Local time distribution of low and middle latitude ground magnetic disturbances at sawtooth injections of 18–19 April 2002, J. Geophys. Res., 110, A07208, doi:10.1029/2004JA010734.  2005-07-08 Abstract: During a magnetic storm of 18 April 2002, quasi-periodic variations of the low-energy electron flux were observed by the LANL satellites at geosynchronous orbit; this phenomenon has been called the “sawtooth event.” During this event, on the ground, magnetic bays and Pi 2 pulsations took place corresponding to each enhancement of the particle flux, and they had features typical to usual substorms. However, unlike typical substorms, the ACE satellite observed no apparent northward turnings of the IMF corresponding to the sawtooth event. In this study, we used ground magnetic data from middle- and low-latitude stations which are distributed widely in the longitudinal direction, selected from the CPMN (Circum-Pan Pacific Magnetometer Network) and INTERMAGNET stations and compared the magnetic variations during the sawtooth event with that of the typical substorm (Lester et al., 1984). We found that the local time distribution of the polarization axis of the Pi 2 pulsations show a good agreement with that for a typical substorm, except that the local time width of the expected current wedge was 12 hours. On the other hand, the H component is predominant in the amplitude of the magnetic bay on the ground; the distribution of the H component also suggests a 12-hour-wide current wedge, which did not develop much in time. From these features, it is suggested that a current wedge was formed during this sawtooth event, and it generated the Pi 2 pulsations on the ground. However, the local time width of the current wedges is much wider than typical substorms, and its uniqueness causes the ground features different from typical substorm-associated magnetic variations on the ground.  Copyright 2005 by the American Geophysical Union. Occurrence statistics of cold, streaming ions in the near-Earth magnetotail: Survey of Polar-TIDE observations Liemohn M. W., T. E. Moore, P. D. Craven, W. Maddox, A. F. Nagy, J. U. Kozyra (2005), Occurrence statistics of cold, streaming ions in the near-Earth magnetotail: Survey of Polar-TIDE observations, J. Geophys. Res., 110, A07211, doi:10.1029/2004JA010801.  2005-07-09 Abstract: Results are presented from a survey of cold ion observations in the near-Earth magnetotail using data from the Polar Thermal Ion Dynamics Experiment (TIDE). During the interval from July to December of 2001, Polar had its apogee (∼9.5 R E) near the equatorial plane in the tail region of the magnetosphere. It is shown that a lobal wind is ubiquitous in the inner tail, with low-energy (<300 eV) ions streaming from the ionosphere downtail. These lobal winds often pass through the plasma sheet, forming bidirectional streams, in addition to the unidirectional beams seen at higher magnetic latitudes. The observance of bidirectional streams is inversely, although weakly, correlated with geomagnetic activity. Bidirectional streams are interpreted as indicating the minimum size of the closed flux tube region. The reduced frequency of bidirectional streams with activity level times is consistent with the thinning of the plasma sheet during these times. It is inferred from the universality of these observations during Polar's passage through the inner tail region that the ionosphere is a continuous supplier of plasma to the near-Earth magnetosphere. The high occurrence rate of these streams means that during geomagnetic disturbances, it is not necessary to wait for outflow and magnetospheric circulation in order to supply the inner magnetosphere with ionospheric ions; these cold streams are an immediately available supply of ionospheric-origin particles.  Copyright 2005 by the American Geophysical Union. Storm-time field-aligned currents on the nightside inferred from ground-based magnetic data at midlatitudes: Relationships with the interplanetary magnetic field and substorms Nakano S., T. Iyemori (2005), Storm-time field-aligned currents on the nightside inferred from ground-based magnetic data at midlatitudes: Relationships with the interplanetary magnetic field and substorms, J. Geophys. Res., 110, A07216, doi:10.1029/2004JA010737.  2005-07-15 Abstract: On the basis of analysis of east-west geomagnetic disturbance fields at midlatitudes, we investigated the characteristics of temporal variations of field-aligned currents on the nightside during geomagnetic storms. The results indicate that upward field-aligned currents develop on the nightside, especially in the postmidnight, when the interplanetary magnetic field (IMF) is directed southward. This suggests that the upward field-aligned currents are principally associated with the convection electric field. It is also found that the upward field-aligned currents in the postmidnight can be intensified at substorm expansion, while they principally depend on the southward component of the IMF. The intensification of the upward currents is regarded as a different physical process from the formation of a substorm current wedge at a substorm expansion. We discuss some possible effects of the IMF and substorms on the generation of the upward currents on the nightside, especially in the postmidnight.  Copyright 2005 by the American Geophysical Union. Toward a synthesis of equatorial spread F onset and suppression during geomagnetic storms Martinis C. R., M. J. Mendillo, J. Aarons (2005), Toward a synthesis of equatorial spread F onset and suppression during geomagnetic storms, J. Geophys. Res., 110, A07306, doi:10.1029/2003JA010362.  2005-07-22 Abstract: We present initial steps toward unifying our understanding of storm time equatorial spread F (ESF) by searching for the common elements in past case studies and statistical occurrence patterns. We show that the development (or inhibition) of equatorial irregularities during magnetically active periods can be understood using the AE -parameterized Fejer-Scherliess model for disturbance vertical drifts versus storm time and local time. This model takes into account the different sources of perturbation electric fields (magnetospheric and ionospheric dynamos) that ultimately drive the equatorial vertical drifts, showing prompt and delayed effects in the premidnight sector (where both generation and suppression can occur), as well as in the postmidnight period where generation dominates. The postsunset period exhibits the greatest variability for storm time ESF versus longitude, and thus we demonstrate the Fejer-Scherliess model's applicability in a test case (6 April 2000) that had an AE pattern compatible with their parameterization scheme. The model successfully accounts for the pronounced longitude confinement in the observed postsunset ESF patterns. Finally, we move beyond the empirically derived relationships between geomagnetic indices and the occurrence of ESF (Aarons, 1991) into a framework of true solar-terrestrial parameters that drive such effects. Additional case studies taken from the published literature are then used to show a consistent linkage between postsunset ESF onset and the interplanetary electric field (IEF) E sw. While AE, Dst, Kp and Dst / dt indices were used in earlier studies to determine the dusk-longitude sector of disturbance electric fields, here we attribute to the IEF the main role in the determination of this longitude sector.  Copyright 2005 by the American Geophysical Union. A statistical analysis of the assimilative mapping of ionospheric electrodynamics auroral specification Kihn E. A., A. J. Ridley (2005), A statistical analysis of the assimilative mapping of ionospheric electrodynamics auroral specification, J. Geophys. Res., 110, A07305, doi:10.1029/2003JA010371.  2005-07-22 Abstract: The assimilative mapping of ionospheric electrodynamics (AMIE) technique utilizes a wide range of electrodynamics measurements to determine high-latitude maps of the electric potential, electron particle precipitation (average energy and total energy flux), and ionospheric conductance (Hall and Pedersen). AMIE does this by conducting a least squares fit to the difference between the data and a background model. This fit is then added to the background model. This allows for a very stable technique with even minimal amounts of data. The background models are typically statistical models that are driven by the solar wind and interplanetary magnetic field or the hemispheric power index. This study presents results of a statistical validation of the AMIE conductance and particle precipitation calculations and quantifies how using ground magnetometer derived measurements improves upon the result obtained using only a background statistical model. Specifically, we compare AMIE using the Fuller-Rowell and Evans (1987) model of particle precipitation and ionospheric conductances to DMSP particle precipitation measurements during the period from May to November 1998. The conductances are derived from the particle precipitation using the Robinson et al. (1987) formulation. The Fuller-Rowell and Evans (1987) results show low (39–21% with increasing AE) energy flux integrals with respect to DMSP auroral passes and differences in mean electron energies. The AMIE runs, in which ground-based magnetometers were used to modify the particle precipitation using the formulation by Ahn et al. (1983) and Ahn et al. (1998), show significant improvement in correlation to the observational data. We show that it more accurately predicts the particle precipitation than when using only the background model, especially in the 1800–0300 MLT nightside sectors where solar conductance is not significant. In addition, the AMIE results show a clear increase in accuracy with increasing number of magnetometers in a sector.  Copyright 2005 by the American Geophysical Union. A new interpretation of Weimer et al.'s solar wind propagation delay technique Bargatze L. F., R. L. McPherron, J. Minamora, D. Weimer (2005), A new interpretation of Weimer et al.'s solar wind propagation delay technique, J. Geophys. Res., 110, A07105, doi:10.1029/2004JA010902.  2005-07-27 Abstract: We present an evaluation of the Weimer et al. (2003) scheme designed to model interplanetary magnetic field (IMF) phase front propagation in the solar wind. The new method is based on the fact that IMF fluctuations tend to be rotations contained within planes. Weimer et al. (2003) report that phase front orientations can be found via minimum variance analysis (MVA) with planar normals defined by the minimum variance direction. The phase plane tilt angle results they present appear to be accurate as they vary in a similar fashion to those found utilizing phase front coplanarity analysis using multipoint interplanetary observations (Weimer et al., 2002). Here we report on an attempt to reproduce their results, an effort that failed since Weimer et al. (2003) adopted a nonstandard form of the equation used to calculate the magnetic field variance matrix that composes the basis of MVA. Use of the modified variance matrix forces a reevaluation of the physics underlying their new propagation model. The revised interpretation suggests that phase plane orientations are organized in a coordinate system whose axes are defined by the mean IMF direction and the minimum and maximum perturbation directions perpendicular to the mean field vector. The phase plane normal is found to be the minimum perturbation direction in this coordinate system. Given that the new technique appears to improve the accuracy of estimating solar wind propagation delays and that it requires IMF data from only one interplanetary monitor, testing it as a space weather forecasting tool is clearly motivated.  Copyright 2005 by the American Geophysical Union. Indirect estimation of the solar wind conditions in 29–31 October 2003 Dmitriev A. V., J.-K. Chao, A. V. Suvarova, K. Ackerson, K. Ishisaka, Y. Kasaba, H. Kojima, H. Matsumoto (2005), Indirect estimation of the solar wind conditions in 29–31 October 2003, J. Geophys. Res., 110, A09S02, doi:10.1029/2004JA010806.  2005-07-28 Abstract: A comparative analysis of the solar wind conditions was performed for extremely disturbed event on 29–31 October 2003. It was found that the ACE and Geotail upstream monitors provided very similar data on the IMF but that plasma measurements in the SOHO CELIAS/MTOF, ACE SWEPAM, IMP 8 MIT, and Geotail CPI experiments are very different. The solar wind velocity was indirectly estimated using the time lag for propagation of such solar wind structures as interplanetary shock, Alfven waves, rotational, and tangential discontinuities from point L1 to the Earth. We found the best correspondence of the estimated velocity was with the ACE SWEPAM data, which displayed very fast (up to 2000 km/s) solar wind, while the IMP 8, Geotail, and SOHO plasma instruments are unable to measure such a fast solar wind stream. Application of the magnetopause models to a data set of numerous geosynchronous magnetopause crossings observed by GOES and LANL satellites enabled estimation of the solar wind dynamic pressure. In general the estimated pressure and density are in agreement with the solar wind plasma parameters provided by the ACE SWEPAM experiment. An estimation of the solar wind density corresponds very well to the electron density restored from the Geotail PWI data. However, during 1600–1800 UT on 29 October, 1700–1800 UT on 30 October, and 0000–0400 UT on 31 October, the estimated solar wind pressure and density are several times larger than provided by the Geotail PWI and ACE SWEPAM. A large helium abundance is considered as a possible reason for the solar wind pressure underestimation in the first case. The understated solar wind density on 30–31 October might be explained by errors in the method for restoring of the plasma data in fast solar wind (>900 km/s) accompanied with intensive fluxes (few tens of particles per cm 2 s sr) of high-energy (>30 MeV) solar energetic protons.  Copyright 2005 by the American Geophysical Union. Comparison of intense nightside shock-induced precipitation and substorm activity Meurant M., J.-C. Gérard, C. Blockx, V. Coumans, B. Hubert, M. Connors, L. R. Lyons, E. Donovan (2005), Comparison of intense nightside shock-induced precipitation and substorm activity, J. Geophys. Res., 110, A07228, doi:10.1029/2004JA010916.  2005-07-28 Abstract: Sudden variations of the solar wind dynamic pressure frequently induce dayside enhancements of auroral activity with features such as high-latitude arcs, low-latitude proton flashes, and enhancement of auroral precipitation propagating dawnward and duskward from noon to the night sector. In some cases, these shocks also induce enhanced activity during which the power precipitated into the night sector may reach values as high as observed during substorms. Several studies have shown that the triggering of nightside-enhanced precipitation is more likely during periods of southward interplanetary magnetic field (IMF) components. Early works showed that substorm-like activity is not frequent after a shock and suggested that shocks may not be considered as substorm triggers. We examine up to what point substorm-like nightside activity triggered by a shock is comparable to an isolated substorm. For this purpose, we analyze three events morphologically similar to substorms and occurring within less than 20 min after the arrival of a pressure pulse on the front of the magnetosphere. Different features of these events such as the mean energy of precipitated electrons, the latitudinal motion of boundaries before and after onset, and the power precipitated into the nightside sector are compared with isolated substorms. We conclude that the characteristics of shock-induced substorms appear very similar to those of isolated substorms. Shocks are able to trigger substorms when they hit an unstable magnetosphere. The interpretation is that the perturbation due to the shock induces a substorm by closure of the plasma sheet magnetic field. For the events presented in this study, the instability result from a period of southward IMF or stretching of the magnetic tail induced by a previous shock.  Copyright 2005 by the American Geophysical Union. Magnetospheric field-line resonances: Ground-based observations and modeling Rankin R., K. Kabin, J. Y. Lu, I. R. Mann, R. Marchand, I. J. Rae, V. T. Tikhonchuk, E. F. Donovan (2005), Magnetospheric field-line resonances: Ground-based observations and modeling, J. Geophys. Res., 110, A10S09, doi:10.1029/2004JA010919.  2005-07-28 Abstract: We present theory and ground-based observations of field-line resonances (FLRs) excited in Earth's magnetosphere. Three FLR observations are reported, which correspond to large-scale standing shear Alfv  Copyright 2005 by the American Geophysical Union. Resolving the enigmatic solar wind disappearance event of 11 May 1999 Janardhan P., K. Fujiki, M. Kojima, M. Tokumaru, K. Hakamada (2005), Resolving the enigmatic solar wind disappearance event of 11 May 1999, J. Geophys. Res., 110, A08101, doi:10.1029/2004JA010535.  2005-08-03 Abstract: On 11 and 12 May 1999, the Earth was engulfed by an unusually low-density (<1 cm −3) and low-velocity (<350 km s −1) solar wind for a period of over 1 day. Extensive studies of this unusual event that occurred during Carrington rotation 1949 (CR1949), using both ground-based and space-based in situ observations, have not as yet been able to identify the cause or the solar source of this event. Using solar wind velocity measurements from the four-station IPS observatory of the Solar-Terrestrial Environment Laboratory (STEL), Toyokawa, Japan, we investigate the structure of the solar wind in May 1999 during CR1949. IPS observations from STEL were used to make tomographic velocity maps to identify and delineate the extent and morphology of the stable solar wind flows during CR1949 in the vicinity of the Earth. Combined with in situ measurements of the interplanetary magnetic field (IMF), potential field computations of the solar magnetic fields in the period, and HeI 10830  Copyright 2005 by the American Geophysical Union. Southern Hemisphere ionosphere and plasmasphere response to the interplanetary shock event of 29–31 October 2003 Yizengaw E., M. B. Moldwin, P. L. Dyson, T. J. Immel (2005), Southern Hemisphere ionosphere and plasmasphere response to the interplanetary shock event of 29–31 October 2003, J. Geophys. Res., 110, A09S30, doi:10.1029/2004JA010920.  2005-08-10 Abstract: We analyze the effects on the Southern Hemisphere ionosphere and plasmasphere due to the 29–31 October 2003 geomagnetic storms (the so-called series of Halloween storms). Solar wind data from ACE and ionospheric data from the GPS (Global Position System) ground and LEO (Low Earth Orbit) receivers, the TOPEX/Poseidon altimeter, the IMAGE FUV camera, and the DMSP drift meter are used to understand the ionospheric dynamics as a function of the storm phase. The detailed structure of the ionosphere has been obtained using tomographic reconstruction applied to data from both ground- and space-based GPS receivers. The tomographic approach using LEO observations of signals received from GPS satellites above the LEO's horizon allows us to investigate the topside ionospheric and plasmaspheric density distribution in more detail than can be obtained using ground-based GPS receivers. This is because with ground-based receivers, the higher topside ionosphere and plasmasphere contribute only a small fraction to the total electron content (TEC) and so the measurements are dominated by the ionospheric structure at the F 2 peak. In contrast, the Australian LEO satellite, FedSat, which has been used for this study, orbits at 800 km altitude, well above the F 2 peak and hence the TEC measured is primarily due to the upper topside ionosphere and plasmasphere. This paper presents the tomographically reconstructed topside ionosphere and plasmasphere electron density distributions using LEO observations. The temporal and regional maps of TEC and the IMAGE FUV data show that the storm that commenced on 29 October dramatically decreased the plasma density in the Southern Hemisphere middle and high latitudes. The region remained depleted of plasma for more than 24 hours until 31 October, when the second severe storm began. TOPEX/Poseidon data shows a daytime localized density enhancement occurred above the middle of the Pacific Ocean. These results show large interhemispheric and longitudinally narrow storm-time structure in the ionosphere and topside ionosphere/plasmasphere.  Copyright 2005 by the American Geophysical Union. Low-frequency plasma oscillations at Mars during the October 2003 solar storm Espley J. R., P. A. Cloutier, D. H. Crider, D. A. Brain, M. H. Acuña (2005), Low-frequency plasma oscillations at Mars during the October 2003 solar storm, J. Geophys. Res., 110, A09S33, doi:10.1029/2004JA010935.  2005-08-11 Abstract: The powerful x-class flare which occurred on the Sun on 28 October 2003 had important effects on plasma environments throughout the solar system. We present here observations of the effects at Mars from the Mars Global Surveyor (MGS) Magnetometer/Electron Reflectometer experiment. In particular we focus on the changes in the nature of the magnetic oscillations observed at an altitude of 400 km (MGS's current orbital altitude) during the passage of the solar storm. We find that strong, regular oscillations are observed in both the B $\parallel$ and B $\perp$ components of the magnetic field at all solar zenith angles. We emphasize in particular the powerful, coherent oscillations observed in the normally quiet nightside region. These oscillations carry power at the proton gyrofrequency and at and below the oxygen gyrofrequency. This implies that ions of planetary origin are interacting with the solar wind plasma and raises the possibility that significant atmospheric loss may occur during the passage of large solar storms at Mars.  Copyright 2005 by the American Geophysical Union. Near-relativistic electron emission following the 28 October 2003 X17 flare Simnett G. M. (2005), Near-relativistic electron emission following the 28 October 2003 X17 flare, J. Geophys. Res., 110, A09S01, doi:10.1029/2004JA010789.  2005-08-13 Abstract: The 28 October 2003 solar flare event was one of the largest electron events above 50 keV of the current solar cycle. The event was associated with a major flare, at least one fast coronal mass ejection (CME), and a prominence eruption. The evolution of the electron spectrum for this event enables us to resolve three, or possibly four, separate electron sources. The source associated with the passage of a fast CME through the corona lasts about half an hour, has a very soft spectrum, and appears at 1 AU as a highly anisotropic beam. The most intense source has a weak outward anisotropy, lasts 2 days before starting a slow decay, and has a hard spectrum. The event is at its most intense around the arrival of the shock which is ahead of the CME, and this is also when the electron spectrum is hardest. One possible interpretation to explain the spectral and angular distribution properties of the electrons from this event is discussed.  Copyright 2005 by the American Geophysical Union. Ionospheric signatures of plasma injections in the cusp triggered by solar wind pressure pulses Cerisier J.-C., A. Marchaudon, J.-M. Bosqued, K. McWilliams, H. U. Frey, M. Bouhram, H. Laakso, M. Dunlop, M. Förster, A. Fazakerley (2005), Ionospheric signatures of plasma injections in the cusp triggered by solar wind pressure pulses, J. Geophys. Res., 110, A08204, doi:10.1029/2004JA010962.  2005-08-18 Abstract: We describe coordinated observations made on 14 July 2001 simultaneously in the midaltitude cusp by Cluster and at the cusp's ionospheric magnetic footprint by Super Dual Auroral Radar Network (SuperDARN) and Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) during a period of three successive solar wind dynamic pressure pulses. In association with each of these pulses, Cluster observes plasma injections while auroral images from the IMAGE spacecraft show enhanced precipitation in the cusp. Following these plasma injections, channels of fast convection flows are observed in the ionosphere by the SuperDARN radars. On the basis of the spatial and temporal relationships between these various signatures, we analyze the response of the dayside magnetosphere and ionosphere to the pressure pulses as follows: (1) the solar wind dynamic pressure pulses are the drivers of plasma injections from the magnetosheath into the cusp; (2) the ionospheric convection bursts start shortly after the auroral intensifications and their duration is much longer (10 min versus 4–6 min for the auroral intensifications); (3) the convection bursts occur on the poleward side of the cusp precipitation; and (4) the Alfv  Copyright 2005 by the American Geophysical Union. Mars Global Surveyor observations of the Halloween 2003 solar superstorm's encounter with Mars Crider D. H., J. Espley, D. A. Brain, D. L. Mitchell, J. E. P. Connerney, M. H. Acu  2005-08-25 Abstract: Like at Earth, disturbances from solar storms affect the space environment as they encounter Mars. The effects of the 28 October 2003 solar superstorm were among the greatest observed by the Mars Global Surveyor spacecraft at Mars to date. The disturbance, defined by an increase in incident solar wind pressure, encountered Mars on 30 October 2003 and persisted for 43 hours. We present the effects of the passage of this high-pressure disturbance and compare the modified Martian space environment to more quiescent times. We find that the horizontal component of magnetic field is increased on the dayside. In addition, the solar wind interaction region is compressed during the disturbance. The solar wind flow has access to lower altitudes than typical, which likely increases mass loss from the Martian atmosphere. Regions of opened magnetic field lines can be closed at 400 km due to the compression of minimagnetospheres, thus altering locations where ionospheric plasma is protected from solar wind scavenging at 400 km altitude.  Copyright 2005 by the American Geophysical Union. Overwhelming O + contribution to the plasma sheet energy density during the October 2003 superstorm: Geotail/EPIC and IMAGE/LENA observations Nosé M., S. Taguchi, K. Hosokawa, S. P. Christon, R. W. McEntire, T. E. Moore, M. R. Collier (2005), Overwhelming O + contribution to the plasma sheet energy density during the October 2003 superstorm: Geotail/EPIC and IMAGE/LENA observations, J. Geophys. Res., 110, A09S24, doi:10.1029/2004JA010930.  2005-08-25 Abstract: We studied dynamics of O + ions during the superstorm that occurred on 29–31 October 2003, using energetic (9–210 keV/ e) ion flux data obtained by the energetic particle and ion composition (EPIC) instrument on board the Geotail satellite and neutral atom data in the energy range of 10 eV to a few keV acquired by the low-energy neutral atom (LENA) imager on board the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite. Since the low-energy neutral atoms are created from the outflowing ionospheric ions by the charge exchange process, we could examine variations of ionospheric ion outflow with the IMAGE/LENA data. In the near-Earth plasma sheet of X GSM ∼ −6 R E to −8.5 R E, we found that the H + energy density showed no distinctive differences between the superstorm and quiet intervals (1–10 keV cm −3), while the O + energy density increased from 0.05–3 keV cm −3 during the quiet intervals to ∼100 keV cm −3 during the superstorm. The O + /H + energy density ratio reached 10–20 near the storm maximum, which is the largest ratio in the near-Earth plasma sheet ever observed by Geotail, indicating more than 90% of O + in the total energy density. We argued that such extreme increase of the O + /H + energy density ratio during the October 2003 superstorm was due to mass-dependent acceleration of ions by storm-time substorms as well as an additional supply of O + ions from the ionosphere to the plasma sheet. We compared the ion composition between the ring current and the near-Earth plasma sheet reported by previous studies and found that they are rather similar. On the basis of the similarity, we estimated that the ring current had the O + /H + energy density ratio as large as 10–20 for the October 2003 superstorm.  Copyright 2005 by the American Geophysical Union. Global auroral responses to abrupt solar wind changes: Dynamic pressure, substorm, and null events Lyons L. R., D.-Y. Lee, C.-P. Wang, S. B. Mende (2005), Global auroral responses to abrupt solar wind changes: Dynamic pressure, substorm, and null events, J. Geophys. Res., 110, A08208, doi:10.1029/2005JA011089.  2005-08-25 Abstract: Global auroral images are used to investigate how specific types of solar wind change relate to the resulting type of auroral-region disturbance, with the goal of determining fundamental response types. For not strongly southward IMF conditions (B z $\gtrsim$ −5 nT), we find that IMF changes that are expected to reduce the convection electric field after $\gtrsim$ 30 min of negative IMF B z cause typical substorms, where expansion phase auroral activity initiates within the expected location of the Harang electric field reversal and expands in ∼10 min to cover ∼5 hours of MLT. For not strongly southward IMF conditions, solar wind dynamic pressure (P dyn) enhancements compress the entire magnetosphere, leading to a global auroral enhancement with no evidence for substorm bulge-region aurora or current wedge formation. Following prolonged strongly southward IMF (B z $\lesssim$ −8 nT), an IMF change leading to convection electric field reduction gives a substorm disturbance that is not much different from substorms for less strongly southward IMF conditions, other than the expansion phase auroral bulge region seems to expand somewhat more in azimuth. However, under steady, strongly southward IMF conditions, a P dyn enhancement is found to cause both compressive auroral brightening away from the bulge region and a Harang-region substorm auroral brightening. These two auroral enhancements merge together, leading to a very broad auroral enhancement covering ∼10–15 hours of MLT. Both current wedge formation and compressive energization in the inner plasma sheet apparently occur for these events. We also find that interplay of effects from a simultaneous IMF and P dyn change can prevent the occurrence of a substorm, leading to what we refer to as null events. Finally, we apply the plasma sheet continuity equation to the IMF and pressure driven substorm responses and the null events. This application suggests that solar wind changes cause substorm onset only if the changes lead to a reduction in the strength of convection within the inner plasma sheet.  Copyright 2005 by the American Geophysical Union. Geosynchronous magnetopause crossings on 29–31 October 2003 Dmitriev A., J.-K. Chao, M. Thomsen, A. Suvorova (2005), Geosynchronous magnetopause crossings on 29–31 October 2003, J. Geophys. Res., 110, A08209, doi:10.1029/2004JA010582.  2005-08-25 Abstract: On 29–31 October 2003, numerous geosynchronous magnetopause crossings (GMCs) were identified using magnetic field data from two GOES satellites and plasma data from four Los Alamos National Laboratory (LANL) satellites. We can distinguish four long-lasting intervals, when geosynchronous satellites observed GMCs in a wide range of local time: at ∼0600–0900 UT 29 October; from ∼1000 UT 29 October to 0400 UT 30 October; from ∼1700 UT 30 October to ∼0800 UT 31 October, and at ∼1100–1300 UT 31 October. During a part of those intervals the GMCs occurred in the dawn and dusk sectors under northward interplanetary magnetic field (IMF) that indicates to magnetospheric compression by extremely high solar wind pressure. We found that at 0400–1000 UT 31 October the compression was accompanied with large-amplitude Pc5 pulsation, which can be attributed to global magnetospheric mode (cavity resonance). Multiple GMCs were revealed for the time interval of Pc5 pulsation occasion. An amplitude of the magnetopause oscillation in noon sector was estimated of about 0.26∼0.6 R E. An application of the magnetopause models enabled us studying the magnetopause dawn–dusk asymmetry, which was revealed on the main phase and in maximum of two great geomagnetic storms on 29 and 30 October. We shown that the asymmetry can be formally represented as a shifting of the dayside magnetopause toward the dusk on average distance of 0.2∼0.3 R E. Besides, in some cases the asymmetry was larger and required a shifting of about 0.4 R E. It was shown that the magnitude of the dawn–dusk asymmetry is related to the internal geomagnetic disturbances rather than to the external conditions in the IMF.  Copyright 2005 by the American Geophysical Union. Undulations on the equatorward edge of the diffuse proton aurora: TIMED/GUVI observations Zhang Y., L. J. Paxton, D. Morrison, A. T. Y. Lui, H. Kil, B. Wolven, C.-I. Meng, A. B. Christensen (2005), Undulations on the equatorward edge of the diffuse proton aurora: TIMED/GUVI observations, J. Geophys. Res., 110, A08211, doi:10.1029/2004JA010668.  2005-08-25 Abstract: Undulations on the equatorward edge of the diffuse proton aurora have been identified by using TIMED/GUVI auroral images in the far ultraviolet wavelengths. While undulations have been previously reported on the duskside (Lui et al., 1982), GUVI observations show the undulation also occurs in the dayside, nightside, and morningside. The GUVI proton auroral images provide direct optical evidence that the undulations occur in the proton aurora. It is also the first detection of the undulation in the dayside indicating strong convection shear in the region. The undulation in the nightside, a wavy structure in the whole diffuse proton aurora, is significantly different from those in the duskside and dayside. While almost all of the undulation events are observed during magnetic storms (Dst < −60 nT), one exceptional case shows undulation in the dayside with Dst = 30 nT. However, the case is associated with a large solar wind speed (650 km/s) and a high dynamic pressure (14 nPa). Coincident DMSP SSIES observations suggest that both large ion drift velocity (>1000 m/s) and strong velocity shear (>0.1 s −1) within the diffuse aurora oval are necessary conditions for the undulation to occur. The SSIES data also indicate the areas with large ion drift velocity and shear move to higher latitudes in the MLT sectors toward midnight. This may explain why the undulation is rarely detected in the nightside.  Copyright 2005 by the American Geophysical Union. Dependencies of high-latitude plasma convection: Consideration of interplanetary magnetic field, seasonal, and universal time factors in statistical patterns Ruohoniemi J. M., R. A. Greenwald (2005), Dependencies of high-latitude plasma convection: Consideration of interplanetary magnetic field, seasonal, and universal time factors in statistical patterns, J. Geophys. Res., 110, A09204, doi:10.1029/2004JA010815.  2005-09-01 Abstract: The database of the nine radars of the Super Dual Auroral Radar Network (SuperDARN) in the northern hemisphere has been analyzed for information on factors that influence the convection of plasma in the high-latitude ionosphere. The velocity measurements were collected over the period 1998–2002. The data were first used to derive a new statistical model of convection that improves upon the earlier one-radar model of Ruohoniemi and Greenwald (1996) in its specification of the dependence of the convection pattern on the magnitude and direction of the IMF in the GSM Y-Z plane. We then derived average patterns for secondary sortings by season, year, and radar. Such dependencies as emerged were most clearly seen by contrasting the results for B y + and B y −. The seasonal effect in the convection pattern is found to have similarities to that of the sign of B y. In particular, the combination of B y +/summer (B y −/winter) reinforces the tendency of the B y sign factor to sculpt the dusk and dawn cells into more round/crescent (crescent/round) shapes and to shift the crescent cell across the midnight MLT meridian. However, these combinations are associated with lower estimates of the total cross polar cap potential drop, Φ PC, while the nonreinforcing combinations produce elevated Φ PC, especially B y −/summer. There is an overall tendency for Φ PC to increase from winter to summer, although the pure seasonal effect on the potential drop is weaker than that of the B y −sign/season factor. We did not find pronounced differences among the patterns derived for the 5 individual years, which spanned the most recent interval of solar cycle maximum. Sorting by radar, we found few differences among the patterns for B y +, but for B y −, variations emerged that are consistent with a possible dependence on universal time (UT). The impacts of season and UT on convection in the high-latitude ionosphere thus depends on the IMF, especially the sign of B y. We speculate that variability in the ionospheric conductivity has a greater effect on magnetosphere-ionosphere coupling under B y − conditions.  Copyright 2005 by the American Geophysical Union. Comparison of geosynchronous energetic particle flux responses to solar wind dynamic pressure enhancements and substorms Lee D.-Y., L. R. Lyons, G. D. Reeves (2005), Comparison of geosynchronous energetic particle flux responses to solar wind dynamic pressure enhancements and substorms, J. Geophys. Res., 110, A09213, doi:10.1029/2005JA011091.  2005-09-09 Abstract: Geosynchronous energetic particle fluxes are used to examine the differences and similarities between the particle disturbances due to an enhancement in solar wind dynamic pressure P dyn and those caused by substorms. Disturbances are also distinguished by IMF conditions. First, for not strongly southward IMF conditions (weakly southward or northward IMF), we find that the magnetospheric compression by a P dyn enhancement usually causes particle fluxes to increase simultaneously at all energy channels. The increase is global around the Earth, but it usually occurs first on the dayside and then propagates to the nightside within a few minutes. We also find that a magnetospheric compression sometimes leads to a flux decrease or no flux change for at least one energy channel at some MLTs, which we attribute to the shape of radial profiles at constant adiabatic invariants. However, we find no evidence for substorm-like injections in our P dyn enhancement events when the IMF is not strongly southward. Following prolonged strongly southward IMF, substorms caused by IMF changes that lead to convection electric field reduction and are not associated with a P dyn change generate flux disturbances that are quite similar to typical substorm flux disturbances for less strongly southward IMF conditions. However, the dispersionless injection front is found over a much wider azimuthal region, sometimes extending to the late afternoonside for protons. We find that under prolonged steady, strongly southward IMF conditions, a P dyn enhancement leads to a two-mode type disturbance. The disturbance due to magnetospheric compression can be clearly identified and is seen primarily on the dayside, and a substorm-like injection associated with current wedge formation is seen on the nightside. The dayside compression effect is seen in both species, but is often more easily identified in the proton fluxes than in the electron fluxes. The substorm-like injection feature is also seen in both species but is usually more evident in the electron fluxes. In the events studied here, the dayside compression disturbance precedes the substorm-like injection on the nightside by a few minutes.  Copyright 2005 by the American Geophysical Union. Solar wind control of the radial distance of the magnetic reconnection site in the magnetotail Nagai T., M. Fujimoto, R. Nakamura, W. Baumjohann, A. Ieda, I. Shinohara, S. Machida, Y. Saito, T. Mukai (2005), Solar wind control of the radial distance of the magnetic reconnection site in the magnetotail, J. Geophys. Res., 110, A09208, doi:10.1029/2005JA011207.  2005-09-09 Abstract: To understand magnetotail dynamics, it is essential to determine where magnetic reconnection takes place in the near-Earth magnetotail during substorms. The Geotail spacecraft thoroughly surveyed the near-Earth plasma sheet at radial distances of 10–31 R E during the years 1995–2003. Thirty-four clear reconnection events were identified using the criterion of strong electron acceleration. Various solar wind parameters prior to each reconnection event were examined in order to find the factor controlling the location of the magnetic reconnection site in the magnetotail. The same analyses were carried out for fast tailward flow events. The most important factor was determined to be the solar wind energy input, which can be expressed by − V x × B s, where V x is the x component of the solar wind velocity and B s is the southward component of the interplanetary magnetic field. It is likely that higher efficiency of energy input, rather than the total amount of energy input, primarily controls the location of magnetic reconnection; magnetic reconnection takes place closer to the Earth when efficiency of energy input is higher. The effect of solar wind dynamic pressure is minor. The present result suggests that the tail magnetic reconnection location during substorms is controlled by solar cycle variations in the solar wind.  Copyright 2005 by the American Geophysical Union. Extreme solar-terrestrial events of October 2003: High-latitude and Cluster observations of the large geomagnetic disturbances on 30 October Rosenqvist L., H. Opgenoorth, S. Buchert, I. McCrea, O. Amm, C. Lathuillere (2005), Extreme solar-terrestrial events of October 2003: High-latitude and Cluster observations of the large geomagnetic disturbances on 30 October, J. Geophys. Res., 110, A09S23, doi:10.1029/2004JA010927.  2005-09-17 Abstract: The extremely large solar eruption on 28 October 2003 caused an intense geomagnetic storm at Earth. A second solar eruption on 29 October resulted in a reintensification of the storm about a day later. Similarities and differences between these two events in terms of solar eruption, solar wind driver, and their resulting effect on the near-Earth environment are investigated and put into context of previous works on storm geoeffectivness. Within the second storm some of the strongest substorms in the history of magnetic recordings occurred in northern Scandinavia. The aim of this study is to investigate the cause and resulting effects of these extreme geomagnetic disturbances on the ionosphere and upper atmosphere, focusing on the northern Scandinavian sector where these disturbances reached extremely high values. During this time period, well after the initial arrival of the Interplanetary Coronal Mass Ejection (ICME), the Cluster spacecraft were located at the flank of the magnetospheric tail. The satellites were passed several times by an inward and consecutively outward moving magnetopause in close relation to the substorm intensifications in northern Scandinavia. We propose that the evolution of these magnetospheric substorm intensifications are influenced by the changing dynamics of the solar wind in the form of increased pressure occurring after a prolonged period of southward Interplanetary Magnetic Field (IMF) and thus excessive energy loading into the magnetosphere prior to the onset of the intensifications. We present evidence of external pressure pulse triggering and possibly also quenching of these substorm onsets and recoveries. In addition, EISCAT data have been used to investigate the detailed local behavior of the ionospheric plasma, giving rise to such extreme disturbances. We found that in this case, extreme combinations of enhanced conductivity and intense electric field resulted in very high current intensities (westward electrojet ∼7.4 MA) and very fast onset of such currents. The $\frac{{\rm d}B}{{\rm d}t}$ associated geomagnetically induced currents caused power failures in southern Sweden.  Copyright 2005 by the American Geophysical Union. Flare-generated shock evolution and geomagnetic storms during the “Halloween 2003 epoch”: 29 October to 2 November Wu C.-C., et al. (2005), Flare-generated shock evolution and geomagnetic storms during the “Halloween 2003 epoch”: 29 October to 2 November, J. Geophys. Res., 110, A09S17, doi:10.1029/2005JA011011.  2005-09-17 Abstract: The October/November 2003 (“Halloween 2003”) epoch of intense solar flares provided an opportunity to test the results of earlier parametric 1.5 MHD studies of interacting interplanetary shock waves. These preliminary studies used an adaptive numerical grid that made it possible to identify products of these interactions. During 28 October to 2 November 2003, three shocks generated by four solar flares were observed at the L1 libration point by ACE/SWEPAM/SWICS/MAG. Two very distinct geomagnetic storms, associated with two of these flares (X17/4B and X10/2B), rank as two of the largest storms of solar cycle 23. The purpose of this paper is to present the use of an adaptive grid 1.5-dimensional MHD model that is initiated at the solar surface to study in detail the three shocks observed at L1 that were generated by the four solar flares. Accordingly, four separate pressure pulses, at the appropriate times and with different strengths and duration, determined via a trial and error procedure, are introduced on the Sun to mimic the four flares. The results show that the simulated solar wind velocity temporal profiles successfully matched the observations at L1. The major objective, to demonstrate the detailed nature of interacting shocks and some of their products after origination from closely spaced solar events, is achieved. In addition, the MHD model is able to suggest the solar sources that are associated with specific geomagnetic storms at Earth.  Copyright 2005 by the American Geophysical Union. Decay of interplanetary coronal mass ejections and Forbush decrease recovery times Penna R. F., A. C. Quillens (2005), Decay of interplanetary coronal mass ejections and Forbush decrease recovery times, J. Geophys. Res., 110, A09S05, doi:10.1029/2004JA010912.  2005-09-20 Abstract: We investigate the relation between Forbush cosmic ray decrease recovery time and coronal mass ejection transit time between the Sun and Earth. We identify 17 Forbush decreases from ground-based neutron count rates between 1978 and 2003 that occur during the same phase in the solar cycle and can be associated with single coronal mass ejections (CMEs) in the SOHO LASCO CME Catalog or previously published reports and with specific interplanetary coronal mass ejections (ICMEs) crossing the vicinity of Earth. We find an anticorrelation between Forbush recovery times and CME transit time that contradicts the predictions of simple cosmic ray diffusive barrier models. The anticorrelation suggests that the decay rate of ICMEs is anticorrelated with their travel speed. Forbush recovery times range from seven times the transit time for the fastest disturbance to a fifth the Sun-Earth transit time for the slowest. To account for the large range of measured recovery times, we infer that the slowest disturbances must decay rapidly with radius, whereas the fastest ones must remain strong. The longest recovery times suggest that the fastest disturbances in our sample decayed less rapidly with radius than the ambient solar wind magnetic field strength.  Copyright 2005 by the American Geophysical Union. Magnetospheric model of subauroral polarization stream Goldstein J., J. L. Burch, B. R. Sandel (2005), Magnetospheric model of subauroral polarization stream, J. Geophys. Res., 110, A09222, doi:10.1029/2005JA011135.  2005-09-22 Abstract: We present a magnetospheric model of the subauroral polarization stream (SAPS) electric potential, parameterized by Kp index (valid for Kp = 4–7), on the basis of a previous study of the average characteristics of SAPS. The model treats the SAPS westward flow channel as a potential drop whose radial location and width decrease as a function of both increasing magnetic local time (MLT) and increasing Kp. The magnitude of the SAPS potential drop decreases eastward across the nightside and increases with increasing Kp. The model SAPS flow channel significantly alters the flow paths of plasma in the afternoon and evening MLT sectors and agrees with an earlier single-event study that used an ad hoc SAPS potential to obtain good agreement with plasmasphere observations. The model performance is tested via comparison with 13 intervals of plasmapause data obtained during the period 1 April through 31 May 2001 by the extreme ultraviolet (EUV) imager on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite. Although the model performs well, the current Kp -based parameterization is somewhat crude, capturing only the gross spatial and temporal SAPS characteristics.  Copyright 2005 by the American Geophysical Union. On the origin and configuration of the 20 March 2003 interplanetary shock and magnetic cloud at 1 AU Berdichevsky D. B., I. G. Richardson, R. P. Lepping, S. F. Martin (2005), On the origin and configuration of the 20 March 2003 interplanetary shock and magnetic cloud at 1 AU, J. Geophys. Res., 110, A09105, doi:10.1029/2004JA010662.  2005-09-23 Abstract: On 20 March 2003, a forward shock was observed in the near-Earth solar wind, followed 8 hours later by an interplanetary magnetic cloud (IMC), in a configuration having several uncommon features: Both were parts of a 38-hour interval containing transient solar outflows that occurred in an extended high-speed stream from a Y-shaped extension of the south polar coronal hole. (In contrast, IMCs, and ejecta in general, were rarely observed within high-speed streams at low heliolatitudes during cycle 23.) The most likely solar source for the IMC is AR 10314, located at S15°, just above the “fork” of the Y-shaped coronal hole. Several solar flares occurred in this active region on 17–18 March, as well as a succession of four coronal mass ejections (CMEs). Velocity considerations narrow the most likely source of the 38-hour interval of activity to two CMEs on 17 March 2003 associated with solar flares at W33° and W39°. The IMC axis had a north-south orientation, which is unusual for IMCs during this solar cycle. Its left-handedness implies an association with a left-skewed coronal arcade, which is less common in the Southern Hemisphere. Considering the shock observed ahead of the IMC, we conclude based on orientation and ram pressure arguments that this shock was not driven by the IMC, as might be presumed, but was the flank of an unrelated shock that overtook the IMC approximately halfway between Sun and Earth, heating the plasma and accelerating particles within the IMC. The CME associated with the X-class flare, at 1208 UT on 18 March in AR 10314 appears to be the solar source for this shock.  Copyright 2005 by the American Geophysical Union. E × B drift simulation in an Eulerian ionospheric model using the total variation diminishing numerical scheme Kulchitsky A., S. Maurits, B. Watkins, J. McAllister (2005), E × B drift simulation in an Eulerian ionospheric model using the total variation diminishing numerical scheme, J. Geophys. Res., 110, A09310, doi:10.1029/2005JA011033.  2005-09-23 Abstract: The University of Alaska Fairbanks Eulerian Polar Parallel Ionospheric Model is a high-resolution model of the polar ionosphere that incorporates multiple ion species. This paper briefly describes this model and the implementation of the total variation diminishing (TVD) advection scheme. The model is based on an Eulerian framework. It is demonstrated that the minimal numerical diffusion of the TVD advection scheme is critical for maintaining ion density gradients with high-resolution Eulerian ionospheric models. The performance of this method is discussed and compared with an upwind numerical scheme. A sample model run for 24 October 2003 that simulates the formation of polar cap ionospheric structures is presented. The results using the TVD advection scheme are compared with the corner transport upwind advection scheme to demonstrate the advantage of the TVD method for simulating steep density gradients and small-scale density structures. These small-scale density features result from time-varying electric fields and are commonly observed using experimental techniques (e.g., incoherent scatter radar) in polar regions.  Copyright 2005 by the American Geophysical Union. Energetic particle observations from the Ulysses COSPIN instruments obtained during the October–November 2003 events McKibben R. B., J. D. Anglin, J. J. Connell, S. Dalla, B. Heber, H. Kunow, C. Lopate, R. G. Marsden, T. R. Sanderson, M. Zhang (2005), Energetic particle observations from the Ulysses COSPIN instruments obtained during the October–November 2003 events, J. Geophys. Res., 110, A09S19, doi:10.1029/2005JA011049.  2005-09-27 Abstract: We report comprehensive observations of solar energetic particle intensities at energies from 0.3 to >100 MeV made by the suite of six Ulysses COSPIN energetic charged particle instruments on the Ulysses spacecraft during the period of intense solar activity in October/November 2003. We also discuss observations of particle anisotropies in selected energy ranges made by these instruments. Located near the orbit of Jupiter and only about 6  Copyright 2005 by the American Geophysical Union. Relativistic nucleon and electron production in the 2003 October 28 solar event Miroshnichenko L. I., K.-L. Klein, G. Trottet, P. Lantos, E. V. Vashenyuk, Y. V. Balabin, B. B. Gvozdevsky (2005), Relativistic nucleon and electron production in the 2003 October 28 solar event, J. Geophys. Res., 110, A09S08, doi:10.1029/2004JA010936.  2005-09-30 Abstract: A flare on 2003 October 28 produced a relativistic particle event at Earth, although the active region AR 10486 was located to the east of the central meridian of the Sun. The paper considers features related to the acceleration at the Sun and the propagation to the Earth of energetic particles in this event, which occurred on a disturbed interplanetary background caused by preceding activity on the Sun and a corotating high-speed solar wind stream. From a study of the onset times of the event at different neutron monitors, we conclude that the earliest arriving solar particles were neutrons. The first relativistic protons arrived a few minutes later. Among relativistic solar protons (RSP), two populations could clearly be distinguished: prompt and delayed ones. The prompt solar protons caused an impulse-like increase at a few neutron monitor stations. The delayed solar protons arrived at Earth 0.5 hours later. Both prompt and delayed relativistic protons arrived at Earth from the antisunward direction. On the other hand, subrelativistic electrons that were traced by their radio emission from meter waves (Nançay Radioheliograph and Decametric Array) to kilometer waves (Wind/WAVES) are accompanied by metric radio emission in the western solar hemisphere, far from the flaring active region. We propose a scenario that reconciles the unusual features of energetic particles at the Earth with the observed structure of the interplanetary magnetic field, which suggests the Earth is at the interface between an interplanetary coronal mass ejection (ICME) and a corotating stream during the event. In this scenario the high-energy protons and electrons are accelerated in the flaring active region, injected into the eastern leg of an ICME loop rooted in the active region, and reach the Earth from the antisunward direction after passing through the summit of the loop. We attribute the promptly escaping subrelativistic electrons to acceleration in the western solar hemisphere and propagation along the nominal Parker spiral.  Copyright 2005 by the American Geophysical Union. From the Sun to the outer heliosphere: Modeling and analyses of the interplanetary propagation of the October/November (Halloween) 2003 solar events Intriligator D. S., W. Sun, M. Dryer, C. D. Fry, C. Deehr, J. Intriligator (2005), From the Sun to the outer heliosphere: Modeling and analyses of the interplanetary propagation of the October/November (Halloween) 2003 solar events, J. Geophys. Res., 110, A09S10, doi:10.1029/2004JA010939.  2005-09-30 Abstract: We use the space weather validated 3-D HAFv2 model to help us study the interplanetary propagation of the October/November 2003 solar eruptions from the Sun to >90 AU and over a wide range of heliolongitudes and heliolatitudes. The HAFv2 model predictions at ACE (1 AU), Ulysses (5.23 AU), Cassini (8.67 AU), Voyager 2 (73 AU), and Voyager 1 (93 AU) are compared with available data. These comparisons indicate the importance of asymmetric interplanetary propagation both in heliolongitude and heliolatitude. We recommend that these effects explicitly be taken into account. The HAFv2 results appear to be useful for interpreting the Voyager 2 and Voyager 1 energetic particle data in the outer heliosphere. They are consistent with the effects of the Halloween solar events observed in the energetic particle data at both spacecraft. The HAFv2 results also may be helpful for predicting the plasma wave 2–3 kHz radio emission previously associated with large shocks and their interaction with the heliopause. Our study indicates that the Halloween events may give rise to 2–3 kHz radio emission in early 2005, assuming that the shocks which propagated beyond Voyager 1 will be strong enough.  Copyright 2005 by the American Geophysical Union. Effect of solar wind pressure enhancements on storm time ring current asymmetry Shi Y., E. Zesta, L. R. Lyons, A. Boudouridis, K. Yumoto, K. Kitamura (2005), Effect of solar wind pressure enhancements on storm time ring current asymmetry, J. Geophys. Res., 110, A10205, doi:10.1029/2005JA011019.  2005-10-08 Abstract: The effect of solar wind pressure enhancements on storm time ring current asymmetry is investigated by examining the asymmetric variations in the north-south (H) and east-west (D) components of the geomagnetic field during four magnetic storms. For two strong storms, on 25 September 1998 and 29 May 2003, pressure enhancements occurred during the main phase with strong and steadily southward IMF B z. It is found that the pressure enhancements significantly increase the asymmetry of the already strong and asymmetric ring current under these conditions. For the moderate magnetic storm on 10 January 1997, a pressure enhancement occurred during the early recovery phase when IMF B z was turning northward while it was still southward. Our result shows that the pressure enhancement also slightly enhanced the asymmetry of the slightly asymmetric ring current that existed during the early recovery phase. On 6 November 2000, a pressure enhancement occurred during the late recovery phase when the IMF B z was strongly northward. For this case, the pressure enhancement did not increase the asymmetry of the already symmetric ring current. The above results of ring current asymmetry increases can be explained by considering the local energization of the preexisting ring current particles by the azimuthal electric field induced by the pressure enhancement. Our results show that the effect of pressure enhancements on the ring current depends strongly on the asymmetry state of the ring current at the times of the onsets of pressure enhancements, which is in turn determined by the IMF B z preconditioning. In addition, the size and relative strength of a pressure enhancement also play important roles in affecting the ground asymmetric H perturbation.  Copyright 2005 by the American Geophysical Union. Electron signatures of active merging sites on the magnetopause Maynard N. C., W. J. Burke, J. D. Scudder, D. M. Ober, D. R. Weimer, K. D. Siebert, C. T. Russell, M. Lester, F. S. Mozer, N. Sato (2005), Electron signatures of active merging sites on the magnetopause, J. Geophys. Res., 110, A10207, doi:10.1029/2004JA010639.  2005-10-13 Abstract: Near magnetopause current layers the Polar satellite often detects field-aligned fluxes of >0.5 keV electrons that carry heat flux away from merging sites along inner/outer separatrices between newly opened and closed/interplanetary magnetic flux. Close to separator lines, electron gyrotropy weakens to break trapping on closed field lines of the outer plasma sheet followed by attachment to newly opened flux at random pitch angles. Energetic electrons in the “tails” of distribution functions quickly move great distances along separatrices to act as surgical indicators of active merging. If IMF B Y is large, field rotation in the magnetopause current layer can be $\ll$ 180  Copyright 2005 by the American Geophysical Union. Characteristics of the interplanetary coronal mass ejections in the heliosphere between 0.3 and 5.4 AU Wang C., D. Du, J. D. Richardson (2005), Characteristics of the interplanetary coronal mass ejections in the heliosphere between 0.3 and 5.4 AU, J. Geophys. Res., 110, A10107, doi:10.1029/2005JA011198.  2005-10-14 Abstract: We identify and characterize interplanetary coronal mass ejections (ICMEs) observed by spacecraft in the solar wind, namely Helios 1 and 2, PVO, ACE, and Ulysses, which together cover heliocentric distances from 0.3 to 5.4 AU. The primary identification signature used to look for ICMEs is abnormally low proton temperatures. About 600 probable ICMEs were identified from the solar wind plasma and magnetic field data from these spacecraft. We use these events to study the radial evolution of ICMEs between 0.3 and 5.4 AU, mainly in a statistical sense. The occurrence rate of ICME approximately follows the solar activity cycle. ICMEs expand as they move outward since the internal pressure is generally larger than the external pressure. The average radial width of ICMEs increases with distance. ICMEs expand by a factor of 2.7 in radial width between 1 and 5 AU. The radial expansion speed of ICMEs decreases with distance and is of the order of the Alfvén speed. The density and magnetic field magnitude decrease faster in ICMEs, which fall off with distance R as R −2.4 and R −1.5, respectively, than in the ambient solar wind; however, the temperature decreases as R −0.7, slightly less rapid than in the ambient solar wind. These results are consistent with previous findings with relatively limited data coverage. We also use a one-dimensional MHD model to investigate the radial expansion of the ICMEs and find that the radial expansion speed is of the order of the Alfvén speed, consistent with the observations.  Copyright 2005 by the American Geophysical Union.

Provan, G., M. Lester, S. W. H. Cowley, A. Grocott, S. E. Milan, B. Hubert, and H. Khan (2005), Modulation of dayside reconnection during northward interplanetary magnetic field, J. Geophys. Res., 110, A10211, doi:10.1029/2004JA010980

20 October 2005 [Abstract]

Huang, C., J. C. Foster, and M. C. Kelley (2005), Long-duration penetration of the interplanetary electric field to the low-latitude ionosphere during the main phase of magnetic storms, J. Geophys. Res., 110, A11309, doi:10.1029/2005JA011202

26 November 2005 [Abstract]

Eriksson, S. et al. (2005), On the generation of enhanced sunward convection and transpolar aurora in the high-latitude ionosphere by magnetic merging, J. Geophys. Res., 110, A11218, doi:10.1029/2005JA011149

23 November 2005 [Abstract]

Huang, C. Y., W. J. Burke, and C. S. Lin (2005), Ion precipitation in the dawn sector during geomagnetic storms, J. Geophys. Res., 110, A11213, doi:10.1029/2005JA011116

19 November 2005 [Abstract]

Mühlbachler, S., C. J. Farrugia, J. Raeder, H. K. Biernat, and R. B. Torbert (2005), A statistical investigation of dayside magnetosphere erosion showing saturation of response, J. Geophys. Res., 110, A11207, doi:10.1029/2005JA011177

11 November 2005 [Abstract]

Lyons, L. R., D. Lee, R. M. Thorne, R. B. Horne, and A. J. Smith (2005), Solar wind-magnetosphere coupling leading to relativistic electron energization during high-speed streams, J. Geophys. Res., 110, A11202, doi:10.1029/2005JA011254

11 November 2005 [Abstract]

Winglee, R. M., W. Lewis, and G. Lu (2005), Mapping of the heavy ion outflows as seen by IMAGE and multifluid global modeling for the 17 April 2002 storm, J. Geophys. Res., 110, A12S24, doi:10.1029/2004JA010909

31 December 2005 [Abstract]

Zhang, T. X., J. X. Wang, and A. Tan (2005), Solar 3He-rich events and abnormal enhancements of heavy-ion isotopes accelerated in two stages, J. Geophys. Res., 110, A12111, doi:10.1029/2005JA011360

24 December 2005 [Abstract]

Throp, K., M. Lockwood, B. S. Lanchester, S. K. Morley, and H. U. Frey (2005), Modeling the observed proton aurora and ionospheric convection responses to changes in the IMF clock angle: 1. Persistence of cusp proton aurora, J. Geophys. Res., 110, A12311, doi:10.1029/2003JA010306

21 December 2005 [Abstract]

Anderson, B. J., S. Ohtani, H. Korth, and A. Ukhorskiy (2005), Storm time dawn-dusk asymmetry of the large-scale Birkeland currents, J. Geophys. Res., 110, A12220, doi:10.1029/2005JA011246

21 December 2005 [Abstract]

Weimer, D. R. (2005), Predicting surface geomagnetic variations using ionospheric electrodynamic models, J. Geophys. Res., 110, A12307, doi:10.1029/2005JA011270

16 December 2005 [Abstract]

Webber, W. R., B. Heber, and J. A. Lockwood (2005), Time variations of cosmic ray electrons and nuclei between 1978 and 2004: Evidence for charge-dependent modulation organized by changes in solar magnetic polarity and current sheet tilt, J. Geophys. Res., 110, A12107, doi:10.1029/2005JA011291

16 December 2005 [Abstract]

Neugebauer, M., and J. Giacalone (2005), Multispacecraft observations of interplanetary shocks: Nonplanarity and energetic particles, J. Geophys. Res., 110, A12106, doi:10.1029/2005JA011380

16 December 2005 [Abstract]

Rae, I. J. et al. (2005), Evolution and characteristics of global Pc5 ULF waves during a high solar wind speed interval, J. Geophys. Res., 110, A12211, doi:10.1029/2005JA011007

15 December 2005 [Abstract]

Tu, J., P. Song, B. W. Reinisch, X. Huang, J. L. Green, H. U. Frey, and P. H. Reiff (2005), Electron density images of the middle- and high-latitude magnetosphere in response to the solar wind, J. Geophys. Res., 110, A12210, doi:10.1029/2005JA011328

15 December 2005 [Abstract]

Owens, M. J., C. N. Arge, H. E. Spence, and A. Pembroke (2005), An event-based approach to validating solar wind speed predictions: High-speed enhancements in the Wang-Sheeley-Arge model, J. Geophys. Res., 110, A12105, doi:10.1029/2005JA011343

15 December 2005 [Abstract]

Svalgaard, L., and E. W. Cliver (2005), The IDV index: Its derivation and use in inferring long-term variations of the interplanetary magnetic field strength, J. Geophys. Res., 110, A12103, doi:10.1029/2005JA011203

13 December 2005 [Abstract]

Zhang, X. X., C. Wang, T. Chen, Y. L. Wang, A. Tan, T. S. Wu, G. A. Germany, and W. Wang (2005), Global patterns of Joule heating in the high-latitude ionosphere, J. Geophys. Res., 110, A12208, doi:10.1029/2005JA011222

9 December 2005 [Abstract]

Watari, S., M. Vandas, and T. Watanabe (2005), Solar cycle variation of long-duration radial interplanetary magnetic field events at 1 AU, J. Geophys. Res., 110, A12102, doi:10.1029/2005JA011165

8 December 2005 [Abstract]