Disturbances in the Magnetosphere and Ionosphere during Spotless Sun

Abstract

Analysis of geomagnetic and ionospheric activity is performed for 541 disturbed days during spotlessSun (Kp 3.0) from 1995 to 2021. Variations of the global ionospheric indices WU (positive disturbancesof total electron content), WL (negative disturbances), their range WE and the planetary index Wp are analyzed.The source W-index characterizes a measure of deviation of the instant total electron content from thequiet median varying from −4 to +4 with a step 1, and the global indices WU, WL, WE, Wp are derived fromthe global maps GIM-TEC of Jet Propulsion Laboratory, JPL. Investigation of the seasonal dependence hasrevealed two levels of the ionosphere disturbances: the low disturbance of the ionosphere during 1996‒1998and 2018‒2021 and the high disturbance during 2004‒2010 and 2016‒2017. The seasonal ionosphere variationsare different for two sets of the data. The seasonal variations of the solar wind velocity Vsw near the Earthorbit are first identified for the 1st data set displaying the peaks at the equinoxes similar to variations of theKp-index. The 2nd set of the high disturbance of the ionosphere refers to the epoch of transition from the highsolar activity SA to low SA characterized by the total restructuring of the physical conditions on the Sun