Comparison of DMSP F13 Cross-Track Ion Drift Velocities With AMIE Results

The Assimilative Mapping Of Ionospheric Electrodynamics (AMIE) model [Richmond et al., J. Geophys. Res., 93, 5741, 1988] has been used in a wide range of studies pertaining to the magnetosphere, ionosphere and thermosphere. In these studies historical data from several different data sources (electric fields from radars and satellites, electric currents from satellites, magnetic perturbations from satellites and magnetometers) have been assimilated. In its real-time mode (rt-AMIE), only data from an array of ground-based magnetometers are assimilated in and convection patterns are produced in one-minute increments. However, the reliability of these real-time patterns for applications involving ionosphere-thermosphere specifications and forecasts has never been systematically tested. To address this issue, a comparison of one year of DMSP F13 cross-track ion drift velocities with AMIE convection patterns based on data from 80 ground-based magnetometers has been conducted. First, for each high-latitude DMSP velocity observation, the corresponding AMIE value was calculated. Then, the measured and calculated cross-track ion drift velocities along the high-latitude pass were compared and criteria were established to determine whether or not the AMIE patterns fit the measurements adequately. The comparisons were done for one year (1998) of satellite crossings of the northern polar region (4300 consecutive satellite crossings). The results indicate that the AMIE patterns adequately represented the DMSP observations about 32% of the time, which is a significant improvement over statistical convection patterns (6% of the time) [Bekerat et al., J. Geophys. Res., 108, 1413, 2003]. This is particularly impressive in view of the fact that only a limited number of ground-based magnetometers are included in the AMIE patterns used in this study.