Seasonal and Solar Cycle Dependence of Energy Transfer Rates in the Auroral E‐Region

Abstract

AbstractWe 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 and 2019. We quantified the integrated electromagnetic (EM) energy transfer rate and the integrated Joule heating rate in the E‐region between 90 and 130 km, which includes the contribution from the neutral winds. We find that (a) the median Joule heating rate and EM energy transfer rate in the evening sector are larger in the winter versus the summer and have similar magnitudes in the spring and fall for the same solar activity and geomagnetic conditions. (b) 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, https://doi.org/10.1029/2009ja014115). (c) The geomagnetic activity level has the most significant impact on the magnitude of the energy transfer rates, followed by seasonal variations, and last the solar activity level.