Evaluation of statistical convection patterns for real‐time ionospheric specifications and forecasts

Abstract

[1] Statistical models of high-latitude plasma convection have been used in a wide range of studies pertaining to the ionosphere and thermosphere, and they are beginning to be used in various space weather applications. However, the statistical convection models only provide average, not instantaneous, convection patterns, and it is not clear if they are real convection patterns or blurred images of convection. It is also unclear how reliable these convection models are for applications involving ionosphere-thermosphere specifications and forecasts. To address these issues, a quantitative analysis was conducted of the Weimer [2001] empirical convection model, which is the most comprehensive model of high-latitude convection that has been constructed to date. First, criteria were established to determine whether or not a modeled convection pattern was correct for a given set of geophysical conditions. The criteria adopted were reasonable but stringent. Then the cross-track ion drift velocities obtained from Weimer [2001] were compared with the corresponding velocities measured by the DMSP F13 satellite. The comparisons were done for nearly a year (1998) of satellite crossings of the northern polar region (4430 successive crossings). The results indicate that the Weimer [2001] model is able to produce the gross structure in the convection pattern, i.e., it is good in a statistical sense. However, it does not adequately capture the mesoscale spatial structure and convection magnitudes observed by the DMSP satellite. Typically, it was able to capture real (instantaneous) convection features in only about 6% of the satellite crossings. Although empirical convection patterns are invaluable for scientific applications, these results have important implications for using empirical convection models in space weather applications.

Validity Study of the Swarm Horizontal Cross‐Track Ion Drift Velocities in the High‐Latitude Ionosphere

“…The empirical models have in common an inherent limitation in that they provide only climatology, that is, average convection patterns (Bekerat et al, 2003). However, usually they are based on a large amount of data, and few may also provide results for arbitrary IMF, solar wind, and dipole tilt angle conditions (Cousins & Shepherd, 2010;Weimer, 2005a).…”

“…However, the model did not adequately capture the observed mesoscale spatial structure and convection magnitudes. It should be noted that only two of the passes presented by Bekerat et al (2003) passed through the centers of the convection cells, and most skimmed the low-latitude boundary of the convection pattern. Eriksson et al (2002) compared Astrid-2 satellite measurements of the electric field with those from the Weimer 2001 model.…”

Antarctic polar plateau vertical electric field variations across heliocentric current sheet crossings

“…Recent publications (Matsuo et al, 2003;Bekerat et al, 2003) have noted that empirical ionospheric convection models of the solar wind-magnetosphere interaction such as the Weimer model may be good in a statistical average sense, but can differ substantially from the actual ionospheric convection at specific instances. It is useful to remember that we are attempting to compare average Weimer-model ionosphere-earth potential differences imposed by the solar wind-magnetosphere generator at Vostok with average electric field variations at that station, around HCS crossings.…”

Comparison of satellite ion drift velocities with AMIE deduced convection patterns

“…First, for any DMSP high-latitude crosstrack ion drift velocity measurement, the corresponding AMIE value was calculated and then the measured and calculated values along any DMSP F13 pass were compared according to our criteria. The criteria adopted are reasonable, but stringent, and are the same as those used recently in comparing the Weimer model with DMSP data (Bekerate et al, 2003). They evolved peak magnitudes being off by more than a factor of 2, flows in the wrong direction for a long distance (sunward versus antisunward), etc.…”