Swarm satellite and EISCAT radar observations of a plasma flow channel in the auroral oval near magnetic midnight |
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Author: | Aikio, A. T.1; Vanhamäki, H.1,2; Workayehu, A. B.1; |
Organizations: |
1Ionospheric Physics Unit, University of Oulu, Oulu, Finland 2International Center for Space Weather Science and Education, Kyushu University, Fukuoka, Japan 3Finnish Meteorological Institute, Helsinki, Finland
4Swedish Institute of Space Physics, Uppsala, Sweden
5Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada |
Format: | article |
Version: | published version |
Access: | open |
Online Access: | PDF Full Text (PDF, 3.3 MB) |
Persistent link: | http://urn.fi/urn:nbn:fi-fe201902215928 |
Language: | English |
Published: |
American Geophysical Union,
2018
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Publish Date: | 2019-02-21 |
Description: |
AbstractWe present Swarm satellite and EISCAT radar observations of electrodynamical parameters in the midnight sector at high latitudes. The most striking feature is a plasma flow channel located equatorward of the polar cap boundary within the dawn convection cell. The flow channel is 1.5° wide in latitude and contains southward electric field of 150 mV/m, corresponding to eastward plasma velocities of 3,300 m/s in the F‐region ionosphere. The theoretically computed ion temperature enhancement produced by the observed ion velocity is in accordance with the measured one by the EISCAT radar. The total width of the auroral oval is about 10° in latitude. While the poleward part is electric field dominant with low conductivity and the flow channel, the equatorward part is conductivity dominant with at least five auroral arcs. The main part of the westward electrojet flows in the conductivity dominant part, but it extends to the electric field dominant part. According to Kamide and Kokubun (1996), the whole midnight sector westward electrojet is expected to be conductivity dominant, so the studied event challenges the traditional view. The flow channel is observed after substorm onset. We suggest that the observed flow channel, which is associated with a 13‐kV horizontal potential difference, accommodates increased nightside plasma flows during the substorm expansion phase as a result of reconnection in the near‐Earth magnetotail. see all
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Series: |
Journal of geophysical research. Space physics |
ISSN: | 2169-9380 |
ISSN-E: | 2169-9402 |
ISSN-L: | 2169-9380 |
Volume: | 123 |
Issue: | 6 |
Pages: | 5140 - 5158 |
DOI: | 10.1029/2018JA025409 |
OADOI: | https://oadoi.org/10.1029/2018JA025409 |
Type of Publication: |
A1 Journal article – refereed |
Field of Science: |
115 Astronomy and space science 114 Physical sciences |
Subjects: | |
Funding: |
This work was supported by the Academy of Finland project 285474. |
Academy of Finland Grant Number: |
285474 |
Detailed Information: |
285474 (Academy of Finland Funding decision) |
Copyright information: |
© 2018. American Geophysical Union. All Rights Reserved. |