IMF Dependence of Midnight Bifurcation in the Thermospheric Wind at an Auroral Latitude Based on Nine Winter Measurements in Tromsø, Norway
Abstract A thermospheric wind data set from a Fabry‐Perot interferometer (630 nm) and the ion velocity from a Dynasonde in Tromsø, Norway, was analyzed for nine winter seasons to study the dynamics of the thermosphere and F‐region ionosphere at an auroral latitude. This study focused on bifurcation...
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| Format: | Article |
| Language: | English |
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Wiley
2023-07-01
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| Series: | Geophysical Research Letters |
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| Online Access: | https://doi.org/10.1029/2023GL104334 |
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| author | S. Oyama K. Hosokawa H. Vanhamäki A. Aikio T. Sakanoi L. Cai I. I. Virtanen K. Shiokawa N. Nishitani A. Shinbori Y. Ogawa |
| author_facet | S. Oyama K. Hosokawa H. Vanhamäki A. Aikio T. Sakanoi L. Cai I. I. Virtanen K. Shiokawa N. Nishitani A. Shinbori Y. Ogawa |
| author_sort | S. Oyama |
| collection | DOAJ |
| description | Abstract A thermospheric wind data set from a Fabry‐Perot interferometer (630 nm) and the ion velocity from a Dynasonde in Tromsø, Norway, was analyzed for nine winter seasons to study the dynamics of the thermosphere and F‐region ionosphere at an auroral latitude. This study focused on bifurcation in the zonal component of the neutral wind and ion velocity at midnight and its dependence on the Y component of the interplanetary magnetic field (IMF). Ionospheric plasma convection patterns are evidently imprinted on the thermospheric wind variations as aspects of the westward and eastward accelerations at dusk and late morning, respectively. The zonal wind bifurcates immediately before midnight for IMF By < 0, but for By > 0, it inverts gradually into the postmidnight sector. Neutral wind streams, originating from higher latitudes, may result in the dependence because of anti‐sunward plasma flow distorted in the polar cap. |
| format | Article |
| id | doaj-art-46480dca218345279f66037e96bcbfeb |
| institution | OA Journals |
| issn | 0094-8276 1944-8007 |
| language | English |
| publishDate | 2023-07-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geophysical Research Letters |
| spelling | doaj-art-46480dca218345279f66037e96bcbfeb2025-08-20T02:11:57ZengWileyGeophysical Research Letters0094-82761944-80072023-07-015014n/an/a10.1029/2023GL104334IMF Dependence of Midnight Bifurcation in the Thermospheric Wind at an Auroral Latitude Based on Nine Winter Measurements in Tromsø, NorwayS. Oyama0K. Hosokawa1H. Vanhamäki2A. Aikio3T. Sakanoi4L. Cai5I. I. Virtanen6K. Shiokawa7N. Nishitani8A. Shinbori9Y. Ogawa10Institute for Space‐Earth Environmental Research Nagoya University Nagoya JapanThe University of Electro‐Communications Chofu JapanSpace Physics and Astronomy University of Oulu Oulu FinlandSpace Physics and Astronomy University of Oulu Oulu FinlandGraduate School of Science Planetary Plasma and Atmospheric Research Center Tohoku University Sendai JapanSpace Physics and Astronomy University of Oulu Oulu FinlandSpace Physics and Astronomy University of Oulu Oulu FinlandInstitute for Space‐Earth Environmental Research Nagoya University Nagoya JapanInstitute for Space‐Earth Environmental Research Nagoya University Nagoya JapanInstitute for Space‐Earth Environmental Research Nagoya University Nagoya JapanNational Institute of Polar Research Tokyo JapanAbstract A thermospheric wind data set from a Fabry‐Perot interferometer (630 nm) and the ion velocity from a Dynasonde in Tromsø, Norway, was analyzed for nine winter seasons to study the dynamics of the thermosphere and F‐region ionosphere at an auroral latitude. This study focused on bifurcation in the zonal component of the neutral wind and ion velocity at midnight and its dependence on the Y component of the interplanetary magnetic field (IMF). Ionospheric plasma convection patterns are evidently imprinted on the thermospheric wind variations as aspects of the westward and eastward accelerations at dusk and late morning, respectively. The zonal wind bifurcates immediately before midnight for IMF By < 0, but for By > 0, it inverts gradually into the postmidnight sector. Neutral wind streams, originating from higher latitudes, may result in the dependence because of anti‐sunward plasma flow distorted in the polar cap.https://doi.org/10.1029/2023GL104334thermosphereionospherehigh latitudeIMF dependence |
| spellingShingle | S. Oyama K. Hosokawa H. Vanhamäki A. Aikio T. Sakanoi L. Cai I. I. Virtanen K. Shiokawa N. Nishitani A. Shinbori Y. Ogawa IMF Dependence of Midnight Bifurcation in the Thermospheric Wind at an Auroral Latitude Based on Nine Winter Measurements in Tromsø, Norway Geophysical Research Letters thermosphere ionosphere high latitude IMF dependence |
| title | IMF Dependence of Midnight Bifurcation in the Thermospheric Wind at an Auroral Latitude Based on Nine Winter Measurements in Tromsø, Norway |
| title_full | IMF Dependence of Midnight Bifurcation in the Thermospheric Wind at an Auroral Latitude Based on Nine Winter Measurements in Tromsø, Norway |
| title_fullStr | IMF Dependence of Midnight Bifurcation in the Thermospheric Wind at an Auroral Latitude Based on Nine Winter Measurements in Tromsø, Norway |
| title_full_unstemmed | IMF Dependence of Midnight Bifurcation in the Thermospheric Wind at an Auroral Latitude Based on Nine Winter Measurements in Tromsø, Norway |
| title_short | IMF Dependence of Midnight Bifurcation in the Thermospheric Wind at an Auroral Latitude Based on Nine Winter Measurements in Tromsø, Norway |
| title_sort | imf dependence of midnight bifurcation in the thermospheric wind at an auroral latitude based on nine winter measurements in tromso norway |
| topic | thermosphere ionosphere high latitude IMF dependence |
| url | https://doi.org/10.1029/2023GL104334 |
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