Persistent solar wind driving of the high-latitude ionosphere during winter night conditions

Abstract

The modelling and prediction of ionospheric storm effects driven by solar wind are still a challenge for the research community. Recently, it has been shown that there exists a persistent modulation of the high-latitude ionosphere with the solar wind variability. Here, we are investigating the potential source mechanisms of the persistent ionosphere modulation during winter night conditions. We us a set of ionosphere observations (EISCAT, IGS Total Electron Content, Tromso ionosonde) as well as AISstorm, a high-resolution numerical model that simulates atmospheric ionization rates caused by precipitating particles. For the approximation of the solar wind energy into the Earth system, we compute the Kan-Lee merging electric field Em provided by OMNI. We studying the correlation and time lag between the variability of Em and the ionospheric parameters and characterize the spatial extent of the regions with highest solar wind correlations. A correlation of ionospheric parameters and Em is present in both, the E- and F-region during winter night condition. The time lag in the E-region (45-90 minutes) is smaller than in the F-region (90-135 minutes). Both, precipitation effects and plasma convection can be observed during the EISCAT campaigns. The region with the highest correlation extends along the auroral oval. The temporal and spatial occurrence agrees well with the occurrence of E- and F-region precipitation reproduced by AISstorm. We conclude that both, precipitation and plasma convection effects, are major contributors to the modulation of the high-latitude ionosphere observations with solar wind variability.