Ionospheric Energy Input in Response to Changes in Solar Wind Driving: Statistics From the SuperDARN and AMPERE Campaigns

Abstract

For over a decade, the Super Dual Auroral Radar Network and the Active Magnetosphere and Planetary Electrodynamics Response Experiment have been measuring ionospheric convection and field‐aligned currents in the high‐latitude regions, respectively. Using both, high‐latitude maps of the magnetosphere‐ionosphere energy transfer rate (the Poynting flux) have been generated with a time resolution of 2 min between 2010 and 2017. These data driven Poynting flux (PF) patterns are used in this study to perform a superposed epoch analysis of the northern hemisphere ionospheric response to transitions of the interplanetary magnetic field Bz component, upwards of 60° geomagnetic latitude. We discuss the difference in the distribution of PF between the magnetosphere‐ionosphere Dungey cycle “switching on” and “switching off” to solar wind driving, revealing that they are not symmetric temporally or spatially.

High‐Resolution Poynting Flux Statistics From the Swarm Mission: How Much Is Being Underestimated at Larger Scales?

“…Early Poynting flux estimations such as these could generally be considered as mostly quasi-static due to the coarse sampling of data and thus large spatial scale. Recently, a combination of SuperDARN and AMPERE (Anderson et al, 2014;Chisham et al, 2007) fitted electric and magnetic field data products has also produced statistical Poynting flux estimations (Billett et al, 2021(Billett et al, , 2022, but these too are likely to a be quasi-static due to the global nature of the SuperDARN and AMPERE fits. As time has passed however, significant data coverage now exists across numerous spacecraft such that statistical studies of the Poynting flux have been made possible with a much higher cadence of measurements (Cosgrove et al, 2022;Ivarsen et al, 2020;Knipp et al, 2021).…”

Multi‐Scale Ionospheric Poynting Fluxes Using Ground and Space‐Based Observations

“…By using the global fits to E and δ B from SuperDARN and AMPERE, the Poynting flux can be derived globally using Equation (Billett, McWilliams, Perry, et al., 2022; Billett et al., 2021; Waters et al., 2004). Figure 1 shows an example SuperDARN/AMPERE Poynting flux calculation, illustrating that it is a powerful technique to achieve a data‐driven snapshot of the global Poynting flux morphology.…”

High-resolution Poynting Flux Statistics from the Swarm Mission: How Much is Being Underestimated at Larger Scales?

“…These studies calculated the Poynting flux using the full electric field vector (E) rather than its perturbation from the back-ground large-scale convection (δE), therefore representing the large-scale quasi-static Poynting flux better than the Alfvénic. However, the quasi-static Poynting flux patterns derived from SuperDARN electric fields and AMPERE magnetic fields by Billett et al (2022) show a much lower magnitude cusp contribution, compared to those from Cosgrove et al (2014) and Knipp et al (2021). We suggest that the latter spacecraft observations may thus be observing some contributions from both quasi-static and Alfvénic Poynt- In this case, the discrepancy is likely due to the higher spatio-temporal resolution of the satellite electric field measurements (1 Hz for DMSP, and between 33 and 4 Hz for FAST) when compared to both SuperDARN and AMPERE, both of which utilise global scale fits to data averaged over several minutes.…”

“…Early Poynting flux estimations such as these could generally be considered as mostly quasi-static due to the coarse sampling of data and thus large spatial scale. Recently, a combination of SuperDARN and AMPERE (Chisham et al, 2007;Anderson et al, 2014) fitted electric and magnetic field data products has also produced statistical Poynting flux estimations (Billett et al, 2021(Billett et al, , 2022, but these too are likely to a be quasi-static due to the global nature of the Su-perDARN and AMPERE fits. As time has passed however, significant data coverage now exists across numerous spacecraft such that statistical studies of the Poynting flux have been made possible with a much higher cadence of measurements (Ivarsen et al, 2020;Knipp et al, 2021;Cosgrove et al, 2022).…”

“…In fact,Knipp et al (2021) do note that an observed hemispheric Poynting flux asymmetry (which we discuss further later) may be due to stronger field-aligned currents, as a result of "an extension of Alfvénic behaviour into what has previously been considered as the "quasi-static" regime". TheBillett et al (2022) SuperDARN/AMPERE statistics, by contrast, could be representing almost entirely the quasi-static Poynting flux.…”