Evaluation of the Mid-Latitude Ionospheric trough Using GRACE Data

Abstract

Our study aims to analyze the main ionospheric trough using K-Band Ranging system (KBR) measurements from the GRACE satellite constellation. The trough was investigated from data over a period from 2002 to 2015, covering both high and low solar activity conditions. The mid-latitude ionospheric trough (MIT) properties are examined for both the Northern and Southern Hemispheres. The MIT is chracterized by its trough’s minimum position, width, depth, and probability. We investigated the dependence of MIT parameters on the magnetic local time, geographic distribution, seasons, and solar and geomagnetic activity conditions, including solar wind plasma speed, interplanetary magnetic field components, and high-resolution geomagnetic indices SYM-H and Hp 30. In this work, we show the elliptical distribution of the mean location of the trough minimum over three seasons for the Northern and Southern hemispheres, as well as the MIT parameter dependency on high-resolution geomagnetic indices. The obtained dependencies regarding MIT climatology and occurrence probability can be used for MIT model validation and the development of new MIT models. Our results confirm and complement previous studies about the MIT dependency on solar activity, season, diurnal variation, and geomagnetic indices.