Seasonal morphology and solar activity dependence analysis of mid-latitude post-midnight enhancement using Global Ionospheric Map

Abstract

In the mid-latitude ionosphere, the anomalous enhancement during nighttime is defined by an increase in electron density of the F2 region and/or total electron content. Studying this phenomenon is important because it enriches our understanding of the complex physical processes responsible for ionosphere formation. Furthermore, long-term investigations can reveal patterns and trends in ionospheric behavior, enabling more accurate predictions and improvements in ionosphere models. In this paper, we have investigated the mid-latitude post-midnight enhancement (MPE) utilizing Global Ionosphere total electron content (TEC) Maps (GIMs) during Low Solar Activity (LSA) years 2009, 2020 and High Solar Activity (HSA) year 2014. The investigation is done in the Northern and Southern Hemispheres during post-midnight hours (0–6 LT) focusing on the occurrence and strength of the MPE according to its seasonal morphology, in addition to the MPE occurrence dependence on the Interplanetary Magnetic Field (IMF) and the influence of the F10.7 on the strength of MPE. The findings indicate that the MPE occurrence and strength are more frequent and stronger during the winter solstice and depend on season, longitude, latitude, and level of solar activity. The MPE occurrence rate and strength reduce when solar activity is higher. The MPE occurrence rate shows a correlation with the IMF's By and Bz components. The negative correlation between F10.7 and MPE strength emphasizes solar activity's impact on MPE.