Temperature enhancements and vertical winds in the lower thermosphere associated with auroral heating during the DELTA campaign

Kurihara, J. and Oyama, S. and Nozawa, S. and Tsuda, T. T. and Fujii, R. and Ogawa, Y. and Miyaoka, H. and Iwagami, N. and Abe, T. and Oyama, K.-I. and Kosch, Mike J. and Aruliah, A. and Griffin, E. and Kauristie, K. (2009) Temperature enhancements and vertical winds in the lower thermosphere associated with auroral heating during the DELTA campaign. Journal of Geophysical Research, 114 (A12306). pp. 1-13. ISSN 0148-0227

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A coordinated observation of the atmospheric response to auroral energy input in the polar lower thermosphere was conducted during the Dynamics and Energetics of the Lower Thermosphere in Aurora (DELTA) campaign. N2 rotational temperature was measured with a rocket-borne instrument launched from the Andøya Rocket Range, neutral winds were measured from auroral emissions at 557.7 nm with a Fabry-Perot Interferometer (FPI) at Skibotn and the KEOPS, and ionospheric parameters were measured with the European Incoherent Scatter (EISCAT) UHF radar at Tromsø. Altitude profiles of the passive energy deposition rate and the particle heating rate were estimated using data taken with the EISCAT radar. The local temperature enhancement derived from the difference between the observed N2 rotational temperature and the MSISE-90 model neutral temperature were 70–140 K at 110–140 km altitude. The temperature increase rate derived from the estimated heating rates, however, cannot account for the temperature enhancement below 120 km, even considering the contribution of the neutral density to the estimated heating rate. The observed upward winds up to 40 m s−1 seem to respond nearly instantaneously to changes in the heating rates. Although the wind speeds cannot be explained by the estimated heating rate and the thermal expansion hypothesis, the present study suggests that the generation mechanism of the large vertical winds must be responsible for the fast response of the vertical wind to the heating event.

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Journal Article
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Journal of Geophysical Research
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Copyright (2009) American Geophysical Union. Further reproduction or electronic distribution is not permitted
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11 Dec 2009 16:32
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01 Feb 2024 00:24