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.

Poynting flux calculated from LEO spacecraft in-situ ion drift and magnetic field measurements is an important measure of energy exchange between the magnetosphere and ionosphere. Defense Meteorological Satellite Program (DMSP) spacecraft provide an extensive back-catalog of ion drift and magnetic perturbation measurements, from which quasi-steady Poynting flux could be calculated. However, since DMSP are operations-focused spacecraft, data must be carefully preprocessed for research use. We describe an automated approach for calculating earthward Poynting flux focusing on pre-processing and quality control. We produce a Poynting flux dataset using 9 satellite-years of DMSP F15, F16 and F18 observations. To validate our process we inter-compare Poynting flux from different spacecraft using more than 2000 magnetic conjunction events. We find no serious systematic differences. We further describe and apply an equal-area binning technique to obtain average spatial patterns of Poynting flux, magnetic perturbation, electric field and ion drift velocity. We perform our analysis using all components of electric and magnetic field and comment on the adverse consequences of the typical single-electric-field-component DMSP Poynting flux approximation on inter-spacecraft agreement. Including full-field components significantly increases the relative strength of near-cusp Poynting flux and increases the integrated high-latitude Poynting flux by ~25%

In previous work (Hairston et al., GRL doi 10.1029/2018GL077381, 2018) we showed the topside F-layer (~850 km) electron temperatures measured by two DMSP spacecraft as they flew through the Moon’s shadow during the 21 August 2017 eclipse exhibited a series of non-uniform, banded decreases rather than a broad and smooth temperature decrease. We found that making a “mask” of the shadow of the Moon eclipsing the existing active regions on the sun’s surface created a pattern on the ionosphere showing where the gradient of the EUV from the active regions was greatest. The complex pattern of these areas from the mask at the F-peak altitude at 300 km corresponded to the areas in the topside F-layer where the DMSP observed the bands of cooled electrons. We have expanded this work to examine about a dozen other eclipses including the most recent 21 June 2020 eclipse. We repeatedly observed the same banded pattern in the electron temperatures in almost all the DMSP eclipse passes, thus demonstrating this is a repeatable phenomenon. Since the DMSP series of spacecraft form a constellation of four operational satellites with the same plasma instrument package making multiple measurements of the shadow at different local times, and sometimes within 10-15 minutes of each other, we can use these observations to map the shape and evolution of these cooling band patterns as the eclipse’s shadow passes over the Earth’s ionosphere. Here we will present our first detailed analysis of the two eclipses that occurred on 20-21 May 2012 and 2 July 2019. Both these eclipses have passes through the duskside by two spacecraft within a few minutes of each other, thus allowing us to examine the evolution of the pattern. We are using these events to determine the empirical patterns seen in the electron temperature decreases during eclipses and to explore the mechanism causing the cooling of the plasma and how it is transported from the F-peak region to the topside ionosphere.