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In support of a multiagency project for assessing induction hazards, we present maps of extreme-value geoelectric amplitudes over about half of the continental United States. These maps are constructed using a parameterization of induction: estimates of Earth surface impedance, obtained at discrete geographic sites from magnetotelluric survey data, are convolved with latitude-dependent statistical maps of extreme-value geomagnetic activity, obtained from decades of magnetic observatory data. Geoelectric amplitudes are estimated for geomagnetic waveforms having 240 s sinusoidal period and amplitudes over 10 min that exceed a once-per-century threshold. As a result of the combination of geographic differences in geomagnetic activity and Earth surface impedance, once-per-century geoelectric amplitudes span more than 2 orders of magnitude and are an intricate function of location. For north-south induction, once-per-century geoelectric amplitudes across large parts of the United States have a median value of 0.26 Vkm; for east-west geomagnetic variation the median value is 0.23 Vkm. At some locations,once-per-century geoelectric amplitudes exceed 3 Vkm.

A time-dependent kinetic model is used to investigate the relative importance of various mechanisms in the early phase decay rate of the ring current. It is found that, for both the solar maximum storm of June 4–7, 1991 and especially the solar minimum storm of September 24–27, 1998, convective drift loss out the dayside magnetopause is the dominant process in removing ring current particles during the initial recovery. During the 1998 storm, dayside outflow losses outpaced charge exchange losses by a factor of ten.

Relativistic electron beam injection simulation results are presented from a new interhemispheric transport model, with a spatial domain reaching from 90 km to 90 km in the conjugate ionospheres. A single beam pulse is injected upward at 700 km during the first time step (10 -4 s) and allowed to scatter and decay through collisional interactions with neu- tral particles and the core plasma. The maximum pulse dura- tion for collisional processes to prevail over the wave-beam instabilities is estimated, and the assumed pulse length is well within this limit. For an L=2 field line, the e-folding time of a 5 MeV beam is 265 s, which is much bigger than the bounce period (0.19 s) and comparable to drift period around the Earth.

A bounced-averaged ring current kinetic model for arbitrary pitch angle, including losses due to charge exchange and Coulomb collisions along ion drift paths, is developed and solved numerically. Results from simplifield model runs, intended to illustrate the effects of adiabatic drifts and collisional losses on the proton population, are presented. The processes of: (1) particle acceleration under the conditions of time-independent magnetospheric electric fields; (2) a predominant loss of particles with small pitch angles due to charge exchange; and (3) a buildup of a low-energy population caused by the Coulomb drag energy degradation, are discussed.

We examine time series of the daily global power (W) radiated by carbon dioxide (at 15 microns) and by nitric oxide (at 5.3 microns) from the Earth s thermosphere between 100 km and 200 km altitude. Also examined is a time series of the daily absorbed solar ultraviolet power in the same altitude region in the wavelength span 0 to 175 nm. The infrared data are derived from the SABER instrument and the solar data are derived from the SEE instrument, both on the NASA TIMED satellite. The time series cover nearly 5 years from 2002 through 2006. The infrared and solar time series exhibit a decrease in radiated and absorbed power consistent with the declining phase of the current 11-year solar cycle. The infrared time series also exhibits high frequency variations that are not evident in the solar power time series. Spectral analysis shows a statistically significant 9-day periodicity in the infrared data but not in the solar data. A very strong 9-day periodicity is also found to exist in the time series of daily A(sub p) and K(sub p) geomagnetic indexes. These 9-day periodicities are linked to the recurrence of coronal holes on the Sun. These results demonstrate a direct coupling between the upper atmosphere of the Sun and the infrared energy budget of the thermosphere.

The complex interplanetary structures during 7 to 8 Nov 2004 are analyzed to identify their properties as well as resultant geomagnetic effects and the solar origins. Three fast forward shocks, three directional discontinuities and two reverse waves were detected and analyzed in detail. The three fast forward shocks 'pump' up the interplanetary magnetic field from a value of approx.4 nT to ~44 nT. However, the fields after the shocks were northward, and magnetic storms did not result. The three ram pressure increases were associated with major sudden impulses (SI + s) at Earth. A magnetic cloud followed the third forward shock and the southward Bz associated with the latter was responsible for the superstorm. Two reverse waves were detected, one at the edge and one near the center of the magnetic cloud (MC). It is suspected that these 'waves' were once reverse shocks which were becoming evanescent when they propagated into the low plasma beta MC. The second reverse wave caused a decrease in the southward component of the IMF and initiated the storm recovery phase. It is determined that flares located at large longitudinal distances from the subsolar point were the most likely causes of the first two shocks without associated magnetic clouds. It is thus unlikely that the shocks were 'blast waves' or that magnetic reconnection eroded away the two associated MCs. This interplanetary/solar event is an example of the extremely complex magnetic storms which can occur in the post-solar maximum phase.

[1] Plasma measurements at geosynchronous orbit are examined via superposed epoch analysis for various storm categories to assess whether superstorms have an unusually altered source population for the storm-time ring current. It is found that certain characteristics of this near-Earth plasma distribution during superstorms are similar to those of moderate or intense storms, or extensions of the trends seen in these lesser storms. These similarities include the dawn sector development of cold, dense plasma. However, other characteristics are unique to superstorms, such as the existence of cold, dense plasma at dusk and midnight. It is concluded that the ring current source during superstorms is a combination of the usual storm-time characteristics as well as an unusually altered component.

[1] Magnetohydrodynamic (MHD) simulations of the Mars magnetic field topology are presented for the auroral observations reported from the Mars Express SPICAM instrument. It is found that the field lines closest to the assumed emission location are open. That is, they are connected to the interplanetary magnetic field, thus allowing access for solar wind electrons to bombard the upper atmosphere and create a auroral-like emission. The most likely population responsible for the creation of the emissions recorded by SPICAM is magnetosheath electrons. It is found that numerous closed magnetic field lines, connected to two strong crustal field regions, can straddle the terminator, leaving open the speculation that atmospheric photoelectrons could be responsible for nightside auroral-like emissions. However, for the particular case of the initially reported SPICAM auroral observations, the MHD results do not produce such terminator-crossing field lines near the emission region.

[1] The question of how much interplanetary shock (IP) events contribute to the geoeffectiveness of solar wind drivers is assessed through numerical experiments using the WINDMI model, a physics-based model of the solar wind-driven magnetosphere-ionosphere system. Analytic fits to solar wind input parameters (B⊥IMF, usw, nsw) allowed shocks and associated shock-sheath plasma to be removed while leaving other features of the solar wind driver undisturbed. Percent changes in WINDMI-derived AL and Dst indices between runs with and without the observed shock and sheath signatures were taken as a measure of its relative contribution to the geoeffectiveness. The major magnetic storms during 15–24 April 2002 and 3–6 October 2000 were selected for this experiment. In both cases, the IP shock and sheath features contributed significantly to the geoeffectiveness of the solar wind driver. The magnetic field compressional jump is important to producing the changes in the AL during these two storm intervals.

[1] Measurements from the Atmospheric Chemistry Experiment show pronounced downward transport of NOx (NO+NO2) to the Arctic stratosphere in Feb–Mar 2006. NOx mixing ratios in the upper stratosphere were 3–6 times larger than observed previously in either the Arctic or Antarctic, aside from the extraordinary winter of 2003–2004. There was only minimal geomagnetic activity in late 2005 and early 2006, however, suggesting that NOx produced via energetic particle precipitation was not significantly elevated. On the other hand, the Arctic polar vortex at stratopause altitudes in Feb 2006 was exceptionally strong, implying greater confinement of air in the polar night. Carbon monoxide data also indicate enhanced confined descent of air from the mesosphere. These results confirm that impacts of EPP on the atmosphere are modulated by meteorological conditions; this has implications for understanding interannual variability and trends in stratospheric NOx and ozone.

We demonstrate extreme ionospheric response to the large interplanetary electric fields during the "Halloween" storms that occurred on October 29 and 30, 2003. Within a few (2 - 5) hours of the time when the enhanced interplanetary electric field impinged on the magnetopause, dayside total electron content increases of approx.40% and approx.250% are observed for the October 29 and 30 events, respectively. During the Oct 30 event, approx.900% increases in electron content above the CHAMP satellite (approx.400 km altitude) were observed at mid-latitudes (+/-30 degrees geomagnetic). The geomagnetic storm-time phenomenon of prompt penetration electric fields is a possible contributing cause of these electron content increases, producing dayside ionospheric uplift combined with equatorial plasma diffusion along magnetic field lines to higher latitudes, creating a "daytime super-fountain" effect.

[1] We present the first study of Low-Charge-State Heavy Ion (LCSHI) events covering a region from Earth's bow shock to the L1 point, obtained with the Suprathermal Ion Composition Spectrometer onboard Wind. STICS is capable of distinguishing charge states of suprathermal ions. In 1995–2000 we found a large number of particle events revealing species of magnetospheric origin. LCSHI events tend to occur in series and in connection with geomagnetic activity. The occurrence rate is found to increase towards solar maximum. The spatial region covered by this particle population ranges from the bow shock to beyond distances of 130 Re, where one of the strongest events occurred. Based on the characterization of LCSHI events we discuss mechanisms for their formation. We conclude that the most probable sources of these ion events are substorms in association with Alfven waves in high-speed solar wind streams and the magnetic storm recovery ring current.

[1] Results from kinetic simulations of hot ion transport in the inner magnetosphere are used to show that the ring current energy content must have a nonlinear (asymptotic) coupling relationship to extreme solar wind conditions due to saturation of the near-Earth convection electric field Ey, conv (defined as a function of cross polar cap potential ΔΦPC). This study examines the Bastille Day magnetic storm (July 14–17, 2000), where the z-component of the interplanetary magnetic field reached −58 nT and the solar wind speed exceeded 1100 km s−1. A large discrepancy in the modeled ΔΦPC confirms a nonlinear response of the high-latitude potential during this event. It is found that this nonlinearity of Ey, conv is necessary to obtain reasonable agreement between the simulation results and the observed geoeffectiveness (Dst) of the storm.

The present investigation is concerned with an analysis of the measurements of the stable auroral red (SAR) arc of October 23, 1981, using data from orbit 1192 of Dynamics Explorer (DE) 2, during which a magnetic coincidence occurred with the DE-1 spacecraft near the red arc field line, and for which simultaneous ground-based intensity measurements from Richland, WA were available. The altitude of the DE-2 satellite was approximately 850 km during arc passage in the Northern Hemisphere and approximately 395 km during the conjugate hemisphere passage. The DE-1 satellite was at an altitude of approximately 6000 km during the magnetic coincidence with DE-2 in the Northern Hemisphere. The described observations and calculations reconfirm a previous understanding that the actual excitation of the O(1D) state responsible for the 6300 A emission of red arcs is caused by hot ionospheric thermal electrons.