Longitudinal Morphology of the Morning Counter Equatorial Electrojet during Low Solar Activity

Abstract

The primary aim of this study is to investigate the longitudinal morphology of the Morning Counter-Equatorial Electrojet (MCEJ) during a period of low solar activity (specifically, the year 2008). The study employed a comparative longitudinal analysis of the Morning Counter-Equatorial Electrojet (MCEJ) during a period of low solar activity. The horizontal magnetic field data from four equatorial stations were collected using the Magnetic Data Acquisition System (MAGDAS). After data cleaning and processing, including hourly binning, baseline determination, and non-cyclic variation correction, MCEJ events were identified based on the negative variations of the H component of the Earth magnetic field during the daytime hours (0600-1800 LT) hrs. The frequency of occurrence, intensity, and timing of these events were analysed across different longitudes and seasons to investigate their longitudinal and seasonal variations. Additionally, the impact of MCEJ events on the noontime equatorial electrojet was assessed. The study identified two categories of MCEJ events. The first type is associated to late reversal of the nighttime westward electric field. The occurrence of the MCEJ event decreases in the eastward direction. The second type is linked to late reversal of the abnormal nighttime eastward electric field and the occurrence frequency increases eastward. Both forms of MCEJ events influence the noontime electrojet, with the first type showing stronger seasonal dependence.