[1] The interplanetary shock/electric field event of 5-6 November 2001 is analyzed using ACE interplanetary data. The consequential ionospheric effects are studied using GPS receiver data from the CHAMP and SAC-C satellites and altimeter data from the TOPEX/ Poseidon satellite. Data from $100 ground-based GPS receivers as well as Brazilian Digisonde and Pacific sector magnetometer data are also used. The dawn-to-dusk interplanetary electric field was initially $33 mV/m just after the forward shock (IMF B Z = À48 nT) and later reached a peak value of $54 mV/m 1 hour and 40 min later (B Z = À78 nT). The electric field was $45 mV/m (B Z = À65 nT) 2 hours after the shock. This electric field generated a magnetic storm of intensity D ST = À275 nT. The dayside satellite GPS receiver data plus ground-based GPS data indicate that the entire equatorial and midlatitude (up to ±50°magnetic latitude (MLAT)) dayside ionosphere was uplifted, significantly increasing the electron content (and densities) at altitudes greater than 430 km (CHAMP orbital altitude). This uplift peaked $2 1/2 hours after the shock passage. The effect of the uplift on the ionospheric total electron content (TEC) lasted for 4 to 5 hours. Our hypothesis is that the interplanetary electric field ''promptly penetrated'' to the ionosphere, and the dayside plasma was convected (by E Â B) to higher altitudes. Plasma upward transport/convergence led to a $55-60% increase in equatorial ionospheric TEC to values above $430 km (at 1930 LT). This transport/convergence plus photoionization of atmospheric neutrals at lower altitudes caused a 21% TEC increase in equatorial ionospheric TEC at $1400 LT (from ground-based measurements). During the intense electric field interval, there was a sharp plasma ''shoulder'' detected at midlatitudes by the GPS receiver and altimeter satellites. This shoulder moves equatorward from À54°to À37°MLAT during the development of the main phase of the magnetic storm. We presume this to be an ionospheric signature of the plasmapause and its motion. The total TEC increase of this shoulder is $80%. Part of this increase may be due to a ''superfountain effect.'' The dayside ionospheric TEC above $430 km decreased to values $45% lower than quiet day values 7 to 9 hours after the beginning of the electric field event. The total equatorial ionospheric TEC decrease was $16%. This decrease occurred both at midlatitudes and at the equator. We presume that thermospheric winds and neutral composition changes produced by the storm-time Joule heating, disturbance dynamo electric fields, and electric fields at auroral and subauroral latitudes are responsible for these decreases.

The series of polar‐orbiting National Oceanic and Atmospheric Administration spacecraft TIROS, NOAA 6, and NOAA 7 have been monitoring the particle influx into the atmosphere since late 1978. This data base has been used to construct statistical global patterns of height‐integrated Pedersen and Hall conductivities for a discrete set of auroral activity ranges. The observations of energy influx and “characteristic electron energy” have been binned in a 1° latitude and 2° magnetic local time grid and ordered by an auroral activity index. This index is an estimate of the energy deposited into a single hemisphere by incident particles, a parameter generated directly from the particle observations and, therefore, internally consistent with the statistical patterns that are constructed. An average electron spectrum is associated with each characteristic energy, which enables a height profile of ionization rate in the upper atmosphere to be determined. The use of a pressure coordinate system insures that the normalized ionization rate profiles are independent of atmospheric model parameters. To create the statistical pattern of height‐integrated conductivities, however, vertical profiles of atmospheric temperature and composition are assumed, and the ion density enhancements are evaluated from a chemical balance between ion production and recombination based on an “effective” recombination coefficient. The data base can also provide the statistical pattern of particle heating rates and ionization rates over a three‐dimensional grid suitable as input to more sophisticated ionospheric and neutral thermospheric codes.

The ionosphere is a highly dynamic medium that exhibits weather disturbances at all latitudes, longitudes, and altitudes, and these disturbances can have detrimental effects on both military and civilian systems. In an effort to mitigate the adverse effects, we are developing a physics‐based data assimilation model of the ionosphere and neutral atmosphere called the Global Assimilation of Ionospheric Measurements (GAIM). GAIM will use a physics‐based ionosphere‐plasmasphere model and a Kalman filter as a basis for assimilating a diverse set of real‐time (or near real‐time) measurements. Some of the data to be assimilated include in situ density measurements from satellites, ionosonde electron density profiles, occultation data, ground‐based GPS total electron contents (TECs), two‐dimensional ionospheric density distributions from tomography chains, and line‐of‐sight UV emissions from selected satellites. When completed, GAIM will provide specifications and forecasts on a spatial grid that can be global, regional, or local. The primary output of GAIM will be a continuous reconstruction of the three‐dimensional electron density distribution from 90 km to geosynchronous altitude (35,000 km). GAIM also outputs auxiliary parameters, including NmF2, hmF2, NmE, hmE, and slant and vertical TEC. Furthermore, GAIM provides global distributions for the ionospheric drivers (neutral winds and densities, magnetospheric and equatorial electric fields, and electron precipitation patterns). In its specification mode, GAIM yields quantitative estimates for the accuracy of the reconstructed ionospheric densities.

The THEMIS mission provides unprecedented multi-point observations of the magnetosphere in conjunction with an equally unprecedented dense network of ground measurements. However, coverage of the magnetosphere is still sparse. In order to tie together the THEMIS observations and to understand the data better, we will use the Open Geospace General Circulation Model (OpenGGCM), a global model of the magnetosphereionosphere system. OpenGGCM solves the magnetohydrodynamic (MHD) equations in the outer magnetosphere and couples via field aligned current (FAC), electric potential, and electron precipitation to a ionosphere potential solver and the Coupled Thermosphere Ionosphere Model (CTIM). The OpenGGCM thus provides a global comprehensive view of the magnetosphere-ionosphere system. An OpenGGCM simulation of one of the first substorms observed by THEMIS on 23 March 2007 shows that the OpenGGCM reproduces the observed substorm signatures very well, thus laying the groundwork for future use of the OpenGGCM to aid in understanding THEMIS data and ultimately contributing to a comprehensive model of the substorm process.

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