TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 58 (No. 9), pp. 1123-1130, 2006

Observations of the lower thermospheric neutral temperature and density in the DELTA campaign

Junichi Kurihara1, Takumi Abe1, Koh-Ichiro Oyama1, Eoghan Griffin2, Mike Kosch3, Anasuya Aruliah2, Kirsti Kauristie4, Yasunobu Ogawa5, Sayaka Komada6, and Naomoto Iwagami6

1Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 229-8510, Japan
2Atmospheric Physics Laboratory, University College London, 67-73 Riding House Street, London W1W 7EJ, U.K.
3Communication Systems, Lancaster University, Lancaster LA1 4WA, U.K.
4Finnish Meteorological Institute, P. O. Box 503, FIN-00101, Helsinki, Finland
5Solar-Terrestrial Environment Laboratory, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan
6Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan

(Received October 2, 2005; Revised May 28, 2006; Accepted June 3, 2006; Online published September 29, 2006)

Abstract: The rotational temperature and number density of molecular nitrogen (N2) in the lower thermosphere were measured by the N2 temperature instrument onboard the S-310-35 sounding rocket, which was launched from Andøya at 0:33 UT on 13 December 2004, during the Dynamics and Energetics of the Lower Thermosphere in Aurora (DELTA) campaign. The rotational temperature measured at altitudes between 95 and 140 km, which is expected to be equal to neutral temperature, is much higher than neutral temperature from the Mass Spectrometer Incoherent Scatter (MSIS) model. Neutral temperatures in the lower thermosphere were observed using the auroral green line at 557.7 nm by two Fabry-Perot Interferometers (FPIs) at Skibotn and the Kiruna Esrange Optical Platform System site. The neutral temperatures derived from the look directions closest to the rocket correspond to the rotational temperature measured at an altitude of 120 km. In addition, a combination of the all-sky camera images at 557.7 nm observed at two stations, Kilpisjärvi and Muonio, suggests that the effective altitude of the auroral arcs at the time of the launch is about 120 km. The FPI temperature observations are consistent with the in situ rocket observations rather than the MSIS model.
Key words: The DELTA campaign, the lower thermosphere, temperature and density.

Corresponding author E-mail: kuri@isas.jaxa.jp

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