Phys.org November 10, 2021
Researchers at the University of Alaska analyzed ground-based remote sensing measurements of thermospheric neutral winds above Alaska, at 240 km altitude to study how space weather affects the well-known large-scale flow that carries winds from the sunlit dayside of the Earth across the polar cap into the night side. This flow feature is typically expected to emerge from the polar cap in the midnight sector and continue blowing equatorward well into sub-auroral latitudes. However, their data showed instances in which the equatorward flow instead stalls over Alaska in an unexpectedly abrupt manner. They found this most prevalent during a low solar activity at mid-winter. At higher latitudes the flow was relatively uniformly anti-sunward around magnetic midnight even during quiet conditions. The finding has implications for spacecraft orbits, space debris avoidance, ionospheric storm modeling and our understanding about the transport of air in the thermosphere. According to the researchers it is likely that the cross-polar jet would also stall elsewhere on the globe at high latitudes as the wind emerges from the polar cap around midnight…read more. Open Access TECHNICAL ARTICLEÂ
This figure shows just the midnight sector of the dial plots compiled together showing three nights…Credit:Â Journal of Geophysical Research, Volume126, Issue10, October 2021, e2020JA028916Â