Overall Morphology of Prominent Zonal Differences in Low Latitude Ionosphere

Abstract

This paper reports the overall morphology of prominent zonal differences in total electron content (TEC) data from Beidou geostationary orbit (GEO) satellites in the low latitude ionosphere over the Asia sector. Using GEO TEC observations from the GXZY receiver (26.2°N, 110.6°E) from 1 November 2019 to 30 November 2022, 64 prominent zonal difference events under geomagnetic quiet conditions were selected. We clarify the global longitude structures corresponding to these prominent zonal difference events at low latitudes through the global TEC products from the Massachusetts Institute of Technology. The structures that can cause the prominent zonal difference features in GEO TEC data are mainly divided into large-scale wave-like structures and featured regional structures. Among them, 19 cases of prominent zonal difference features were caused by large-scale wave-like structures, and 45 cases were caused by regional longitude structures. Prominent zonal differences generated from Large-scale wave-like structures are explained by the day-to-day variation of wave components, which creates an amplitude superposition and amplifies the crest intensity in a region. The featured regional structures cover a longitudinal range of about 10°–30°. In addition, we discussed the possible reasons for this small longitudinal structure by utilizing plasma drift velocity data at the magnetic equator from the Ionospheric Connection Explorer mission. The delicate longitude structures of vertical and zonal plasma drift likely contribute to the prominent zonal difference features in certain events.