Hemispheric Asymmetries in Poynting Flux Derived From DMSP Spacecraft

Abstract

We 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.