Analysis of ground-based and satellite observations of F-region behavior during the great magnetic storm of July 15, 2000

Abstract

Ground-based and satellite data on the total electron content (TEC), ion density, and velocity are analyzed to determine the main processes forming the TEC enhancement at middle and low latitudes during the great magnetic storm of July 15, 2000. According to the model presented here, a southward neutral wind can provide the small TEC enhancement observed at middle latitudes during the daytime. However, a large TEC enhancement occurred at low latitudes in the evening sector after a sudden drop in D st and this enhancement can only be explained by the penetration of a strong electric field at middle and low latitudes. Using an eastward electric field of about 6 mV/m makes it possible to describe a very high TEC enhancement in the crest of the equatorial anomaly and a poleward displacement of the crest before sunset. Simultaneously, the model indicates a significant depletion in the equatorial trough. A very large value for the ratio of TEC (crest)/TEC (trough) is a result of these processes. One of the main features of the electron density height profiles calculated by the model under these conditions is a very high F 2 peak altitude. The analysis also leads to the conclusion that sunward convection of plasma must be taken into account to explain the spatial distribution of the TEC enhancement shown by GPS maps in the North American sector.