Incoherent Scatter Radar Observations of Auroral E-region Thermospheric Winds: Investigating Geomagnetic and Seasonal Variability

Thermospheric winds at E-region altitudes are difficult to measure on a routine basis and therefore are difficult to specify within thermospheric models. While the chemical tracer technique has provided the most comprehensive set of altitude resolved measurements of E-region winds, the technique requires rocket launches which occur irregularly. Incoherent scatter radar techniques have been developed to estimate the thermospheric winds at E-region altitudes. Since 2008, nearly continuous observations from the Poker Flat Incoherent Scatter Radar (PFISR) have been possible, which are conducive for quantifying E-region thermospheric winds at auroral latitudes. These continuous observations provide an important and unique data set in which neutral wind climatology can be investigated as a function of season and over a range of geomagnetic activity levels. We present results from this 10+ year database of altitude-resolved E-region neutral wind profiles. Previous incoherent scatter radar investigations have found differences in the wind patterns between seasons. We present mean neutral wind profiles derived for each season and compare our results with previous ISR investigations. We also subdivide our dataset according to geomagnetic activity level using relevant geomagnetic indices (i.e., AE, Ap, Kp, etc) and the electric field vector. We examine how enhanced plasma convection associated with distrubed intervals impacts the altitude-resolved neutral winds. We present results of nearly continuously sampled E-region neutral wind observations obtained from PFISR at auroral latitudes which can be used as a potential data source for thermospheric wind models and as a dataset that thermospheric models should be able to reproduce.