The Solar Wind Impact on Magnetosphere and Identification of the IMF by Component with Use of the Ground-Based Magnetic Data

A method is reported to determine, by data of the ground-based magnetic observations in polar cap, the quasi-sectorial (with periodicity from 7 to 27 days) SS* structures in the interplanetary magnetic field (IMF) BY component. The BY effect in the polar cap magnetic variations is revealed only under summer condition, when the high ionospheric conductivity ensures availability of ionospheric current systems, responsible for appropriate magnetic disturbances. It is shown that BY structures, reconstructed from the polar cap magnetic data during summer months, are in best conformity with actual variations of the IMF By component, measured onboard the ACE spacecraft in the Lagrange point L1. The reported method can be used for identification of the actual IMF BY component coupling with the magnetosphere. A great advantage of the method over other methods, based on the satellite measurements, is permanent, on-line available information on the real solar wind parameters affecting the magnetosphere. It implies that the BY IMF component, identified by the ground-based magnetic data, can be applied to verify and to validate information on solar wind parameters (https://omniweb.gsfc.nasa.gov/), obtained by distant monitors far upstream of the magnetosphere.