University of Oulu

Cai, L., Oyama, S.‐I., Aikio, A., Vanhamäki, H., & Virtanen, I. ( 2019). Fabry‐Perot interferometer observations of thermospheric horizontal winds during magnetospheric substorms. Journal of Geophysical Research: Space Physics, 124, 3709– 3728.

Fabry‐perot interferometer observations of thermospheric horizontal winds during magnetospheric substorms

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Author: Cai, L.1,2; Oyama, S.1,2,3; Aikio, A.1;
Organizations: 1Ionospheric Physics Unit, University of Oulu, Oulu, Finland
2Institute for Space-Earth Environmental Research (ISEE), Nagoya University, Nagoya, Japan
3National Institute of Polar Research (NIPR), Tachikawa, Japan
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.7 MB)
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Language: English
Published: American Geophysical Union, 2019
Publish Date: 2019-10-23


The high‐latitude ionosphere‐thermosphere system is strongly affected by the magnetospheric energy input during magnetospheric substorms. In this study, we investigate the response of the upper thermospheric winds to four substorm events by using the Fabry‐Perot interferometer at Tromsø, Norway, the International Monitor for Auroral Geomagnetic Effects magnetometers, the EISCAT radar, and an all‐sky camera. The upper thermospheric winds had distinct responses to substorm phases. During the growth phase, westward acceleration of the wind was observed in the premidnight sector within the eastward electrojet region. We suggest that the westward acceleration of the neutral wind is caused by the ion drag force associated with the large‐scale westward plasma convection within the eastward electrojet. During the expansion phase, the zonal wind had a prompt response to the intensification of the westward electrojet (WEJ) overhead Tromsø. The zonal wind was accelerated eastward, which is likely to be associated with the eastward plasma convection within the substorm current wedge. During the expansion and recovery phases, the meridional wind was frequently accelerated to the southward direction, when the majority of the substorm WEJ current was located on the poleward side of Tromsø. We suggest that this meridional wind acceleration is related to a pressure gradient produced by Joule heating within the substorm WEJ region. In addition, strong atmospheric gravity waves during the expansion and the recovery phases were observed.

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Series: Journal of geophysical research. Space physics
ISSN: 2169-9380
ISSN-E: 2169-9402
ISSN-L: 2169-9380
Volume: 124
Issue: 5
DOI: 10.1029/2018JA026241
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: This research has been supported by a fellowship for postdoctoral research from Japan Society for the Promotion of Science (JSPS), a Grant‐in‐Aid for Scientific Research (16H06286, 16K05569, and 16H02230) and Special Funds for Education and Research (Energy Transport Processes in Geospace) from MEXT, Japan, and the research grant by Academy of Finland, decision 285474.
Academy of Finland Grant Number: 285474
Detailed Information: 285474 (Academy of Finland Funding decision)
Copyright information: © 2019. American Geophysical Union. All Rights Reserved.