Field-aligned currents influence on the ionospheric electric fields: Modification of the Upper Atmosphere model

Abstract

We have modified the electric field calculation block of the global three-dimensional time-dependent model of the Earth’s Upper Atmosphere (UAM) to study the influence of the interplanetary magnetic field (IMF) on the ionospheric electric fields. The spatial and temporal distributions of field-aligned currents (FACs) flowing between the ionosphere and the Earth’s magnetosphere are specified from the Lukianova empirical model, which is based on statistical distributions of FACs by Orsted, CHAMP, and Magsat satellites magnetometer data and takes into account the dependence of FACs on the IMF. The modified version of the UAM is verified with the help of model calculations of the global distribution of the electric field for two IMF vector orientations: By = Bz = 0 and By = 0, Bz =–5 nT. An analysis of calculated latitude–longitude FACs density and electric field potential distributions in geomagnetic coordinates at an altitude of 175 km shows that the modified version of the UAM makes it possible to take into account the dependence of ionospheric electric fields on the IMF, the influence of currents in Region 3, and the seasonal variation of FACs.