The anomaly of plasmapause and ionospheric trough positions from DEMETER data

Abstract

The paper addresses the study of the specific pattern of the subauroral ionosphere marked with the anomalous positions of the plasmapause, the equatorial boundary of the mid-latitude (main) ionospheric trough, and the light-ion trough under quiet solar and geophysical conditions near the magnetospheric shell with the McIlwain parameter L = 3. The anomaly was identified on the base of data of active experiments with the SURA heating facility on October 2, 2007, which were conducted as part of the SURA-International Space Station (SURA-ISS) program in the framework of the DEMETER satellite mission. Joint analysis of the orbital data from DEMETER and ISS, together with the results of the complex ground-based measurements, shows that the revealed effect, which is characteristic of the premidnight sector north of the Moscow-SURA satellite path, is not local. It is observed in a vast territory, extending from the west to the east along the same L-shell, from at least Sweden to Kamchatka. The conclusions suggested by the DEMETER data are supported by analysis of the meridional distributions of the F2-peak plasma frequencies provided by GPS radio probing of the ionosphere. Comparison of these results with the model latitudinal-longitudinal and meridional distributions of the F2-peak plasma density provided by the IRI 2007 and SMI (Russian standard model of the ionosphere) models shows that the model predictions are at odds with the empirical data.