Ionosphere Over Eastern North Atlantic Midlatitudinal Zone During Geomagnetic Storms

Abstract

An ionospheric response at middle latitudes to geomagnetic storms is not yet very well understood. Total electron content (TEC) variations associated with eight strong geomagnetic storms between 2015 and 2022 obtained from GNSS receivers in the western area of the North Atlantic (Portuguese continental and insular territory) are studied in an attempt to fill this gap. It was found that for most of the studied geomagnetic storms TEC variations are synchronous for the longitudinal ranges from 27ºW and 9ºW. In the southern part of the studied region (around 32ºN) the amplitude of TEC variations is, in general, significantly higher than in the northern part (around 39ºN). Some of the studied geomagnetic storms were associated with TEC variations that we interpret as effects of post-sunset equatorial plasma bubbles that travelled well north from their habitual region. Also, while most of the studied storms were accompanied by reports on different kind of malfunction of GNSS systems (GPS; GALILEO and other), there is no clear pattern in their appearance in dependence on the geomagnetic/ionospheric storms’ strength, commencement time, and its characteristics, in general.