TY JOUR TI Virtual magnetograms -- a tool for the study of geomagnetic response to the solar wind/IMF driving KW Solar wind--magnetosphere interaction KW dayside-nightside coupling KW sawtooth events KW substorm KW virtual magnetograms KW ULF waves JO Russian Journal of Earth Sciences AU Kozyreva, O.V. AU Pilipenko, V.A. AU Soloviev, A.A. AU Engebretson, M.J. PY 2019 IS 19 PB Geophysical Center of the Russian Academy of Sciences