| Autor: |
Shin-ichiro Oyama, Heikki Vanhamäki, Lei Cai, Anita Aikio, Michael Rietveld, Yasunobu Ogawa, Tero Raita, Mirjam Kellinsalmi, Kirsti Kauristie, Boris Kozelov, Atsuki Shinbori, Kazuo Shiokawa, Takuo T. Tsuda, Takeshi Sakanoi |
| Jazyk: |
angličtina |
| Rok vydání: |
2022 |
| Předmět: |
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| Zdroj: |
Earth, Planets and Space, Vol 74, Iss 1, Pp 1-17 (2022) |
| Druh dokumentu: |
article |
| ISSN: |
1880-5981 |
| DOI: |
10.1186/s40623-022-01710-6 |
| Popis: |
Abstract The thermospheric wind response to a sudden westward turning of the ion velocity at a high latitude was studied by analyzing data obtained with a Fabry–Perot interferometer (FPI; 630 nm), Dynasonde, and Swarm A & C satellites during a conjunction event. The event occurred during a geomagnetically quiet period (Kp = 0 +) through the night, but some auroral activity occurred in the north. The collocated FPI and Dynasonde measured the thermospheric wind (U) and ionospheric plasma velocity (V), respectively, in the F region at the equatorward trough edge. A notable scientific message from this study is the possible role of thermospheric wind in the energy dissipation process at F-region altitude. The FPI thermospheric wind did not instantly follow a sudden V change due to thermospheric inertia in the F region. At a pseudo-breakup during the event, V suddenly changed direction from eastward to westward within 10 min. U was concurrently accelerated westward, but its development was more gradual than that of V, with U remaining eastward for a while after the pseudo-breakup. The delay of U is attributed to the thermospheric inertia. During this transition interval, U∙V was negative, which would result in more efficient generation of frictional heating than the positive U∙V case. The sign of U∙V, which is related to the relative directions of the neutral wind and plasma drift, is important because of its direct impact on ion-neutral energy exchange during collisions. This becomes especially important during substorm events, where rapid plasma velocity changes are common. The sign of U∙V may be used as an indicator to find the times and locations where thermospheric inertia plays a role in the energy dissipation process. Graphical Abstract |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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