TY JOUR TI Asymmetry in occurrence of the leading and following polarities in the photospheric magnetic field at the early stage of active region formation KW magnetic field KW active regions JO Solar-Terrestrial Physics AU Григорьев, В.М. AU Ермакова, Л.В. AU Хлыстова, А.И. PY 2020 IS 6 PB Институт солнечно-земной физики СО РАН