SOLAR-WIND CONTROL OF THE DIURNAL-VARIATI ON OF THE GROUND-LEVEL ATMOSPHERIC ELECTRIC-FIELD

An analysis of fair weather atmospheric electricity, one of the enviro nmental factors which affects the biosphere, is conducted. A distinct difference in the diurnal variation of atmospheric electric field at H elsinki is found between disturbed and extremely quiet conditions in t he magnetosphere in winter before midnight. The comparison with the nu merical model of the ionospheric electric field based on the solar win d parameters reveals that the maximum contribution of the magnetospher ic-ionospheric generator to atmospheric electric field is about 100-15 0 v/m which assumens values of about 30% of the surface field.