We present new results using data collected by the Poker Flat Incoherent Scatter Radar (PFISR) of energy transfer rates which include the effects from neutral winds in the high latitude E-region ionosphere-thermosphere (IT) during Fall 2015. The purpose of our investigation is to understand the magnetic local time (MLT) dependence of the peak energy transfer, which occurs asymmetrically in the morning-evening (dawn-dusk) MLT sector. The statistical characteristics of both altitude-resolved and altitude-integrated energy transfer rates in the auroral E region local to PFISR during different geomagnetic conditions are quantified. Our analysis shows that the geomagnetic activity level has a large impact on the energy transfer rates. In contrast with previous investigations, we find both the altitude integrated electromagnetic (EM) energy transfer rate and Joule heating rate are larger in the evening sector than in the morning sector during all geomagnetic activity conditions. We also observe non-negligible negative EM energy transfer rates below 110 km in the morning sector during active conditions, which is associated with neutral winds during this MLT interval. The statistical results show that the neutral winds tend to increase the Joule heating rate in a narrow altitude range in the morning sector and impact a broader region with respect to altitude and time in the evening sector in the E region under moderate and active conditions. We find that during quiet conditions that the neutral winds have a significant contribution to the Joule heating and contribute up to 75% of the Joule heating. However, during active conditions, the enhanced fields are a dominant driver of Joule heating, while the neutral wind effects can reduce the Joule heating rates by 25% or more relative to the passive heating rates.

In this presentation, we seek to understand the altitudinal response of the auroral E-region neutral wind to substorms using observations from the Poker Flat Incoherent Scatter Radar (PFISR). Zou et al. (2009) presented different nighttime ion drift pattern associated with three different types of substorm events whose onset locations were at, to the east and to the west of PFISR. In addition, Zou et al. (2021) presented different types of latitudinal responses of the F-region neutral wind to substorm events and suggested that the response is highly local time dependent. While these two studies give much insight on the F region ion and neutral responses during substorm events, the E region neutral wind response is not well-understood. Previous studies showed that during disturbed conditions E-region winds, in particular below 110 km, are larger than what tidal theory predicts, while the winds in the upper E-region shows strong impacts from the convection flow. We select events whose onset locations are over the PFISR radar site, but in different MLT sectors using the SuperMag data product during 2010-2019. We present a superimposed epoch analysis of three different types of events after subtracting the quiet background neutral winds. This study will further our understanding of the contribution in a statistical view from forces that are associated with the E-region wind variation during substorm events during different MLT sectors and spanning the altitude range from 90-130 km.

We report one of the first comprehensive ground-based investigations of energy transfer rates in the E-region ionosphere compared relative to geomagnetic activity, seasonal effects, and solar activity level using nearly continuously sampled data collected with the Poker Flat Incoherent Scatter Radar (PFISR) between 2010-2019. We quantified the integrated electromagnetic (EM) energy transfer rate and the integrated Joule heating rate in the E-region between 90-130 km, which includes the contributions from the neutral winds. We find that (1) the median Joule heating rate and electromagnetic (EM) energy transfer rate in the evening sector is larger in the winter versus the summer and have similar magnitudes in the spring and fall for the same solar activity and geomagnetic conditions. (2) The seasonal dependence of the energy transfer rates is closely associated with the seasonal variations of the electric fields. Our analysis shows that the larger EM energy transfer and Joule heating rates in disturbed conditions in the winter versus the summer are associated with the combined effects of both the electric field and Pedersen conductance with the electric field playing a dominant role. Given that the Pedersen conductance in the evening sector is closely related to the particle precipitation and field-aligned currents in the auroral region, this study provides complementary ionospheric evidence of the winter-summer asymmetry of the intensity and density of field-aligned currents (e.g. Ohtani et al., 2009). (3) The geomagnetic activity level has the most significant impacts on the magnitude of the energy transfer rates, followed by seasonal variations, and last the solar activity level.