Hemispheric Asymmetries in Poynting Flux Derived From DMSP Spacecraft

Abstract

AbstractWe provide high‐resolution maps of quasi‐static Poynting flux (PF) in each hemisphere based on nine‐satellite years of Defense Meteorological Satellite Program (DMSP) data. Conjugate comparisons from ∼850 km reveal more quasi‐static PF arriving in the northern hemisphere (NH) than the southern hemisphere (SH). This tendency is clear in the dawn‐dusk sectors and during intervals when Kp < 3, which accounts for ∼80% of the study interval. Summer‐to‐summer comparisons indicate this asymmetry is partially associated with more NH solar illumination, which supports stronger NH field‐aligned currents (FAC). Differing hemispheric FAC configurations may also play a role. Our findings support and broaden earlier reports of similar NH preference for the deposition of Alfvenic PF. Regionally the NH has stronger dusk‐region PF, while the SH has stronger mid‐morning PF. We find PF deposition in the near‐cusp regions that rivals and often exceeds the PF intensity in the auroral zones.