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Spatial variation of electric fields in the high‐latitude ionosphere

1982; American Geophysical Union; Volume: 87; Issue: A7 Linguagem: Inglês

10.1029/ja087ia07p05202

2156-2202

Zi M, Erling Nielsen,

Solar and Space Plasma Dynamics

The patterns of ionospheric electron drift velocities at high latitudes have been determined during 18 magnetically disturbed days using observations made with the STARE system. These patterns have been compared with those which are characteristic for magnetically quiet days determined from 11 days of STARE measurements. The changes from magnetic quiet to active times are (1) the electric field magnitude increases, (2) the average location of the field maximum moves to lower latitudes, (3) the maximum field occurs closer to noon in both the morning and afternoon cell, (4) the maximum electric field, which is observed after midnight during quiet days, is observed during the afternoon instead, (5) the morning convection cell increases, and (6) the reversal from westward to eastward directed electron drifts and vice versa occurs earlier in local time. All these trends become increasingly clear as the Kp index increases. Comparisons with model predictions suggest that variations in the spatial distribution and intensities of ionospheric conductivities as well as variations of the relative strength of the intensities of the field‐aligned current pair flowing in the morning and dusk sector are closely associated with the observed phenomena.