Ground and Ionospheric Signatures of Solar Wind-Magnetosphere Interaction at Mid-Latitudes

Abstract

As we enter the increasing solar activity epoch, the space weather phenomena and predictions become crucially important to avoid the effects on our lives and technology which is becoming more space-dependent every day. One of the key issues in space weather is to determine the worldwide signatures of the solar wind-magnetosphere-ionosphere coupling. While the response of the high and low latitude regions on Earth to the space weather phenomena is well established, the signatures at the mid-latitudes comparatively are less explored. Being farther from both the auroral and the equatorial latitudes, mid-latitude signatures of the solar wind-magnetosphere interaction can be more complex and may not be so straightforward. In this study, the effects of the geomagnetic activity are investigated using observational tools which are unique to its geographical region, north-west Turkey. Dynasonde radar measurements (Dynasonde at ITU Campus, 41°N, 29°E), magnetotelluric measurements of ground electric field (Magnetotelluric station at Bozcaada, 39.5°N, 26°E), and geomagnetic field variations (Geomagnetic observatory at Iznik, 40.43°N, 29.72°E) are combined to obtain a global perspective of the space weather effects in this mid-latitude region. Magnetically active periods were determined using Dst index and the variations in the corresponding ionospheric electron density and the geomagnetically induced currents (GICs) were analyzed based on the case studies as well as statistical tools.  More than 20 indicators such as differences in the fields, extreme values, averages, and storm durations were analyzed and their relations to magnetic storms as well as solar wind and interplanetary magnetic field (IMF) connections were studied.  GICs were investigated based on the variations in the horizontal magnetic field. The dependence on the magnetic storm phases was revealed. One of the most intriguing results from both case studies and statistical analysis is that stronger GICs were found in our region during the recovery phase of the geomagnetic storms. The electron density variations indicated both positive and negative effects during the storms.  The magnitudes of the variations for both GICs and electron density variations were determined.  While the case studies indicate close relations with geomagnetic indices, solar wind, and IMF variations, statistical results resulted in small correlation coefficients.  This emphasizes and further indicates the importance of the statistical indicator that is used in the correlation analysis. In this presentation, solar wind-magnetosphere connection to the ionosphere and to the ground will be discussed in view of our findings.  It is believed that these results will improve our understanding of the cause-and-effect of the space weather phenomena at mid-latitudes while at the same time, it will give support to global space weather modeling studies.