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

• Published in: Geophysical research letters Vol. 50; no. 10
• Main Authors: Billett, D. D., McWilliams, K. A., Ponomarenko, P. V., Martin, C. J., Knudsen, D. J., Vines, S. K.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28-05-2023; Wiley
• Subjects: Atmosphere; Convection; Convection patterns; Dynamics; Earth atmosphere; Electric field; Electric fields; Energy balance; Energy dissipation; Energy exchange; Fluxes; Ground-based observation; Instruments; Ionospheric convection; Ionospheric dynamics; Magnetospheres; Radar; Radar networks; Resolution; Satellite constellations; Satellites; Solar wind; Space weather; Upper atmosphere
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL103733

Three events are presented where high‐resolution measurements from the Swarm satellites coincided with excellent F‐region ionospheric coverage from The Super Dual Auroral Radar Network (SuperDARN). Large‐scale ionospheric convection patterns from SuperDARN, together with field‐aligned‐current patterns from he Active Magnetosphere and Planetary Response Experiment (AMPERE), provide information on quasi‐static ionospheric dynamics traversed by Swarm. Because the Swarm observations and orbital path coincided with favorable SuperDARN/AMPERE observing conditions, it was possible to filter the Swarm electric field observations into a quasi‐static component that agreed with the SuperDARN electric field. The residual electric field from Swarm is thus indicative of small‐ and mesoscale dynamics not captured by the convection and field‐aligned current (FAC) patterns. Calculations of the Poynting flux between the different instruments show that dynamics on small‐to mesoscales can be highly variable within structures like FACs. In the events shown, small‐ and medium‐scale Poynting fluxes occasionally dominate over those from large‐scale processes.
Plain Language Summary
A significant amount of energy from the solar wind deposited into the upper atmosphere of Earth (above ∼100 km altitude) is contained within small‐scale (on the order of kilometers) fluctuations of the electric field. This kind of variability is difficult to measure do the sparse resolution (both in space and time) of instruments like ground‐based instruments, or the global fitting procedures of satellite constellations. Those instruments, which tend to focus on observing large‐scale “big picture” dynamics, do however excel at providing important information about the global state of the upper atmosphere. Small‐scale (∼1 km) data from the Swarm satellites is used in this letter, in conjunction with ground‐based radars and a satellite constellation, to obtain a complete picture of how space weather energy dissipation is spread across all scale sizes. It is found that small features that only Swarm can see occasionally dominate in terms of energy balance.
Key Points
Filtered electric fields from the Swarm satellites agree with SuperDARN
Variable and high‐magnitude Poynting flux structures are embedded in and between field‐aligned currents
Poynting flux from sub‐quasi‐static dynamics can comprise as much as half of the total