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 , .. AU , .. AU , .. AU , .. PY 2019 IS 19 PB Геофизический центр Российской Академии Наук