Hiwind Balloon Fabry-Perot Interferometer Measurements Show the Importance of the Solar Wind Influence on Thermospheric Density and Wind Models at Quiet Times

Abstract:

Recent measurements by the HIWIND balloon have revealed persistent dayside equatorward winds in the earth’s thermosphere at high latitudes during geomagnetically quiet times. Although thermospheric density models have included the effects of magnetic storms, they have not included a dependence on solar wind conditions affecting the energy and configuration of charged particles in the earth’s magnetosphere at geomagnetically quiet times. Consequently, most thermospheric models could not predict the direction of the high-latitude winds at geomagnetically quiet times, nor could they predict the depth of the thermospheric density minimum at the last solar minimum in the year 2009. We discuss the importance of having a solar wind index appropriate to the needs of thermospheric density models.