SA43A-1059 1340h
Multi-parameter characterization of ionospheric and magnetospheric responses to the October-November 2003 super storms
The October-November 2003 super storms provide us with a unique opportunity to investigate the responses of the ionosphere and the magnetosphere to extreme solar wind and interplanetary magnetic field conditions, based on the reliable data set provided by the ACE team. A set of observation data from both space and ground, including geomagnetic indices, cross polar cap potential has been used to study these events. The geomagnetic indices represent ionospheric and magnetospheric responses to the solar wind and the interplanetary magnetic fields in different region and on different time scales, and they can be used to determine the relationships between various drivers and multi-response parameters. The empirical models of magnetospheric convection field, geomagnetic field, ionospheric conductivity, and neutral wind have been used to study the cross-polar cap potential, the field aligned current, the Joule heating patterns of the high-latitude ionosphere during the periods of these storms. The cross polar cap potential data taken from DMSP F13 during the super storms has been used to compare with the output of the empirical model so as to see if the polar cap potential from the model can be used to be an effective replacement of the observed polar cap potential drop. The solar flare x-ray and energetic particle fluxes from geosynchronous FY-2 satellite have been used to study the geosynchronous space environments during these super storms. The preliminary analysis of the data has indicated that dramatic variations of geosynchronous space environments have been observed by China FY-2 satellite in responding to the super storm times, and the FY-2 data can be used to provide with us space environment alerts for geosynchronous satellites and spacecrafts.
SA43A-1060 1340h
Observation of the Solar Wind and Magnetosphere Interaction Near the Subsolar Point During Active Geomagnetic Periods on October 24 and 31, 2003
In October of 2003 the major axis of the IMAGE spacecraft's orbit was roughly aligned with the Sun-Earth line, with a dayside apogee extending approximately eight Earth radii from the Earth. This fortuitous orientation provided the opportunity to make measurements near the nose of the magnetosphere. Starting at $\sim$1530 UT on October 24 and again at $\sim$0530 UT on October 31---both periods of elevated geomagnetic activity---the LENA telescope on IMAGE recorded high counting rates of nominal $\sim$keV neutral hydrogen distributed in an unusually wide angular distribution centered on the Sun. These LENA signals are unique to these two periods and concurrent plasma and neutral atom measurements from the RPI and HENA instruments on IMAGE also reveal unusual, difficult to explain features. We use solar wind particle measurements from the SWEPAM instrument on the ACE spacecraft to compare the solar wind flux and thermal spread with the LENA data and as an input into magnetopause and bow shock models. These models show magnetospheric contractions that are well aligned with variations in the IMAGE observations, suggesting that the spacecraft may have entered the supersonic solar wind. Although this interpretation explains many of the observations, we continue to examine alternative explanations suggested by some features in the data. We also study the possibility of a connection between the unusual LENA observations and a similar, commonly observed diffuse signal thought to arise from solar wind charge exchange in the magnetosheath
SA43A-1061 1340h
Ionospheric Observations Made During Major Storms by DMSP and Champ
The in-situ observations of the ionosphere during major storms as observed by the DMSP and the CHAMP spacecraft will be reviewed with special emphasis on the storm periods of April 17-18, 2002 and October 29-31, 2003. These observations include both high and low latitude observations of the thermal plasma, the electric field and the field-aligned currents. The relationship between these observations and SAPS (Sub Auroral Plasma Streams) will be explored. While neutral winds are not measured, the re-distribution of low and mid-latitude plasma is used to estimate the neutral wind in the F region.
SA43A-1062 1340h
Observations of the Ionospheric Response in the Subauroral E-region to the Extreme Geomagnetic Storms of October and November 2003
The Millstone Hill incoherent scatter radar (42.6N, 288.5E, 53Mlat) observed the ionospheric behavior during both the October and November 2003 superstorm events. The effects of these storms in the subauroral E-region are described and compared to those of the Bastille Day storm (July 15, 2000). During all three events, the Millstone Hill radar observed major increases in the ion and electron temperature as well as in the electron density. During the October 29-30, 2003 storm, the E-region ion temperature increased to 800-1000 K (i.e. by a factor of 2), while the electron density increased by a factor of 5. Simultaneous increases in both ion temperature and electron density are observed in the afternoon and evening sectors (18-24 UT) and are found to coincide with observations of a strong (250 m/s) vertical ion drift indicating the presence of an extremely enhanced electric field. Stronger ion heating, up to 1300 K, and a larger enhancement in electron density were observed on November 20, 2003, when the radar was located in the noon and evening sectors. These effects were also accompanied by a stronger (up to 400 m/s) vertical ion drift. These observations illustrate the penetration of storm effects in latitude and altitude in response to extreme geomagnetic storm drivers.
SA43A-1063 1340h
Stormtime Measurements of Topside Ionospheric Upflow from DMSP
We have examined characteristics of the vertical ion flux of thermal O$^+$ in the topside high-latitude ionosphere before and during a number of geomagnetic storms, including the October and November, 2003 events, using measurements of the vertical ion drift and ion number density made by the DMSP F13 and F15 spacecraft. Prior to storm onset typical upward fluxes of approximately 10$^8$-10$^9$ cm$^{-2}$s$^{-1}$ are observed in the auroral zones with somewhat smaller downward fluxes in the polar caps. Immediately following storm onset upward fluxes reach and sometimes exceed 10$^{10}$ cm$^{-2}$s$^{-1}$ and are observed with vertical velocities of 500--1500 m s$^{-1}$. At the same time downward fluxes at the higher latitudes reach unusually high values of 10$^9$ cm$^{-2}$s$^{-1}$. Separately integrating the upwards and downwards fluxes over the high-latitude region (auroral zone and polar cap) for each spacecraft pass allows the observation of total upflow/downflow during the progression of a geomagnetic storm. A superposed epoch analysis of events from 1998 to 2004 reveals a pattern of sudden onset of upwards flux (averaging approximately 14 hours) with a gradually increasing and more extended period of downward flux (lasting about 24 hours). The upwards fluxes are stronger when the coincident fluctuations in the z-component of the IMF are larger.
SA43A-1064 1340h
First Ground-Based Measurements of OI 6300 \AA $ $ Daytime Aurora Over Boston in Response to the 30 October 2003 Geomagnetic Storm
High-Resolution Imaging Spectrograph using Echelle grating (HIRISE) is a high-spectral resolution (0.12 \AA $ $ at 6300 \AA) spectrograph developed at Boston University that is capable of unambiguously measuring the daytime airglow/auroral emissions buried in the strong solar background continuum of the daytime sky. HIRISE measurements of OI 6300 \AA $ $ emissions made during daytime on 30 October 2003 from Boston revealed a prolonged auroral activity from 1415 - 1900 LT. The solar zenith angles varied from 70$^{o}$ - 115$^{o}$ during that interval. Intense enhancement in brightness of as high as 38 Kilo Rayleighs were observed at 1509 LT. These magnitudes were six times larger than the normal daytime emission rates for that day. During this event the solar zenith angle was 74$^{o}$ and the solar background continuum was 4 Mega-Rayleighs \AA$^{-1}$. Such large enhancements in brightness were due to the daytime aurora generated in response to an X-class Coronal Mass Ejection on the Sun. The measured daytime airglow emissions show good agreement, both, in the magnitudes and in the temporal variability with the emissions modeled by using as inputs the N$_{e}$, T$_{e}$ and T$_{i}$ profiles that were measured by the Millstone Hill Incoherent Scatter Radar located 100 km away from the spectrograph. It was possible to make such unique measurements due to the measurement capability of HIRISE. Such measurements present a new perspective in understanding complex Space Weather interactions, especially during such severe geomagnetic storms.
SA43A-1065 1340h
Looking at the November 20, 2003 super storm with TIMED/GUVI: Comparison with the TIMEGCM
During October and November 2003, Earth was subjected to record-class solar flares and geo-effective coronal mass ejections that caused massive perturbations of the upper atmosphere and ionosphere. Observations of the storm effects are available from the NASA TIMED satellite. Among the four TIMED instruments is the Global Ultra Violet Imager (GUVI), a far ultraviolet (FUV) spectrograph that can be operated in imaging or spectrograph modes. GUVI produces images of the far ultraviolet (FUV) dayglow on both the Earth disk below the satellite and on the limb. Among ionospheric and thermospheric parameters that can be extracted from the imaging data are maps of the atomic oxygen to molecular nitrogen column density ratio and altitude-latitude images of the number density and temperature profiles on the limb. GUVI recorded dramatic changes in these quantities on November 20 and 21, a period when the TIMED orbit was favorable for retrieving composition and temperature from the limb dayglow. We will review GUVI observations during that storm, showing examples of composition and temperature. These will be compared with the initial predictions of the Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model. This preliminary comparison reveals many similarities between the model and data. High temperatures seen in the GUVI data are reproduced in the model. And significant perturbations in the composition are also reproduced by the TIMEGCM. But significant differences are also noticed in several areas. In particular, GUVI observes a much less rapid recovery of the perturbed thermosphere than predicted. These and other quantitative conclusions demonstrate that FUV imaging will ultimately play a major role space weather imaging analogous to that of visible or infrared monitoring in tropospheric weather.
SA43A-1066 1340h
Forecasting the magnetospheric dynamics during the superstorms of October-November 2003
The nonlinear dynamical models of the coupled solar wind-- magnetosphere system derived from observational data have the advantage of capturing the essential features inherent in the data. The correlated data of the solar wind and magnetospheric response have been widely used to develop data-derived models. However these models are largely based on the data of periods when the magnetosphere is weakly driven. For example, the widely used Bargatze et al. (1985) data corresponds to a declining phase of the solar cycle and contain only a few weak storms. A correlated database of solar wind and magnetospheric time series data for the peak of the last solar cycle (2000--2001) is compiled to model the magnetospheric dynamics under strong driving. The solar wind variables obtained from ACE measurements while the magnetospheric response consists of geomagnetic indices as well as magnetic perturbations measured by ground magnetometers. This database is used to develop dynamical models of superstorms and forecasts are made for the storms of October-- November 2003. These models yield highly improved forecasts, with correlation coefficients of about 0.8 and can be improved further by actively monitoring the state of the solar wind and then using the data from the corresponding states in the database. These results show that the magnetospheric states during superstorms are inherently distinct from those of less active periods.
SA43A-1067 1340h
GUVI/TIMED Observations of the auroral inputs and thermospheric response during the October and November 2003 Superstorms
The GUVI instrument on the NASA TIMED Mission observes the ionosphere and thermosphere as well as the auroral inputs. In this paper we explore the connection between the geospace environment and the Earth's atmosphere - in particular we follow the particle chain. We report evidence between a direct coupling between the ring current and the upper atmosphere. Observations by GUVI show rapid (~hour) increases in the 1356 A brightness over all latitude in the nightside ionosphere. The increases are simultaneous with substorm injections observed by the High Energy Neutral Atom (HENA) imager on board the IMAGE satellite. These observations suggest that energetic (10-100 keV) Oxygen atoms, produced by charge exchange of the O+ in the ring current, precipitate directly from the ring current region onto the upper atmosphere. The local solar time dependent distribution of the neutrals is also altered by the deposition of electrons and protons, energized in the magnetosphere, at auroral latitudes. The aurora extended well below 40 deg north latitude at times. We compare the average quiet-time behavior of the upper atmosphere, as derived from GUVI observations, to that observed during these storms. We find that there are very large depletions in atomic oxygen that extend nearly to the magnetic equator. These O depletions, which should result in a negative ionospheric storm, are also observed in GPS TEC measurements. We also find evidence for localized O density enhancements and/or the uplift of the ionosphere by the neutral winds and electric fields which lead to a positive ionospheric storm. We also will show results from our studies of the ionosphere: we compare the seasonal distribution of the ionosphere (its total density, peak density, and peak height) for quiet and disturbed conditions. Our model simulations indicate that we are seeing a direct manifestation of the role of the storm induced winds and penetration electric fields in the Earth's upper atmosphere.
SA43A-1068 1340h
ULF Waves penetrating into the slot region during the october 2003 "Halloween" Storms
The aims of this research was to study the ULF waves characteristics during the to "Halloween" storms of 2003. Using magnetic field data from the CANOPUS, IMAGE and SAMNET ground based magnetometer arrays it is shown that the ULF wave power was enhanced during these storms to very high levels and high wave power was observed penetrating to an unusually very low L during 29 October, 2003. On this day particle flux data from the SAMPEX spacecraft shows deep injection and acceleration of relativistic electron into the slot region with this enhancement continuing for days. Therefore, also studied is the relationship between the observed ULF waves and the slot region enhancements.
SA43A-1069 1340h
Characterization of Intense ULF Wave Power Spectra During the ``Halloween'' 2003 Geomagnetic Storm
Large amplitude Pc5 ULF waves observed by the CANOPUS, IMAGE and SAMNET magnetometer arrays are characterized during the Halloween 2003 storm. Following storm onset, very large ULF power in discrete frequencies penetrates to very low-$L$ shells spanning in the entire outer radiation belt and into the slot region. This is especially pronounced during 29th October 2003, coincident with the inwards motion of the outer radiation belt into the slot. ULF power is observed with discrete spectral peaks, and using multiple arrays we characterize the global structure of the ULF spectra and examine the excitation of latitudinally localized power enhancements. Comparing the observed waves to the cross-phase derived Alfven continuum, we determine the role of localized discrete field line resonances in the accumulation of this ULF wave power. Further, using the observed Alfven continuum, we examine the Alfven speed profiles on this day and compare the observed wave frequency spectra and power penetration to low-$L$ to that expected theoretically. Finally, comparisons of the ULF power penetration are used to evaluate order of magnitude diffusive transport rates and to investigate the possibility that ULF wave transport can explain the observed radiation belt electron flux transport.
SA43A-1070 1340h
MHD Simulation of Solar Wind Magnetosphere Coupling During the Halloween Magnetic Storm
The magnetic storm activity that took place at the end of October and beginning of November in 2003 was one of the most intense on record, especially during a period of nominal solar minimum. We have simulated the event using the Lyon-Fedder-Mobarry global MHD code. In this presentation we will examine solar wind magnetosphere coupling duirng the event by comparing the simulation results with actual observations. In particular, there were two episodes of magnetopause crossings by the GOES spacecraft that we compare to the simulation results interpolated to the GOES positions. Such comparisons allow us to determine the validity of the simulation results and hence the validity of the physics represented by the model during extreme magnetic storms.
SA43A-1071 1340h
Large Storm Energy Deposition and Solar Wind Drivers: A Study of Geoeffectiveness
We examine the role of solar wind driving conditions in the deposition of large amounts of energy in the magnetosphere-ionosphere system. Our database consists of eight storms ranging in size, including especially the October and November 2003 superstorms. We estimate energy deposition into the ring current, ionospheric Joule heating, and auroral precipitation for each event and compare with relevant solar wind data. Results suggest that the magnetosonic Mach number of the solar wind may be a useful parameter in identifying the potential for large amounts of energy deposition, possibly because of the role of the bow shock in modulating the magnetosheath field, and therefore its influence of reconnection rates. We use Dst, ionospheric indices, and MHD simulation results where available to investigate the magnetospheric response to different types of solar wind energy input. Our results are examined with a focus on superstorms and the driving conditions observed in connection with them.
SA43A-1072 1340h
IMAGE in the Solar Wind During the October 31, 2003 Event
During the large October 31, 2003 solar storm event, the Low Energy Neutral Atom (LENA) Imager on the IMAGE spacecraft observed unusual behavior in the neutral solar wind. For a nearly two-hour interval centered near 0630 UT, the diffuse neutral solar wind signal which results from solar wind charge exchange in the magnetosheath disappeared leaving only a weak signal from the direction of the Earth and a stronger signal from the Sun direction. The Radio Plasma Imager (RPI) data indicate that the IMAGE spacecraft was in interplanetary space at the time of the unusual neutral solar wind observations and based on an analysis of RPI-stimulated plasma resonance and the cut-off frequency of a type III solar burst reveal a solar wind electron number density of 20-40 cm${}^{-3}$. These densities are substantially larger than the solar wind proton densities measured by ACE at this time, by a factor of 5-10. The LENA neutral solar wind observations can be qualitatively reproduced by assuming the proton densities are comparable to the higher RPI-derived electron densities, but not by using the observed ACE solar wind proton densities. Furthermore, preliminary ring current simulations using the observed ACE solar wind proton densities disagree with Dst* by about an order of magnitude based on the simulated ring current energy. We will also discuss the effect of this density discrepancy on ring current simulations.