HR: 08:40h
AN: SA41A-03    [Abstracts]
TI: In Situ Observations of Neutral Temperature and Density in the Polar Lower Thermosphere during the DELTA Campaign
AU: * Kurihara, J
EM: kuri@isas.jaxa.jp
AF: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Sagamihara, 229-8510 Japan
AU: Abe, T
SA41A-03 AF: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Sagamihara, 229-8510 Japan
AU: Oyama, K
SA41A-03 AF: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Sagamihara, 229-8510 Japan
AU: Griffin, E
SA41A-03 AF: Atmospheric Physics Laboratory, University College London, 67-73 Riding House Street, London, W1W 7EJ United Kingdom
AU: Kosch, M
SA41A-03 AF: Communication Systems, Lancaster University, Lancaster, Lancaster, LA1 4WA United Kingdom
AU: Aruliah, A
SA41A-03 AF: Atmospheric Physics Laboratory, University College London, 67-73 Riding House Street, London, W1W 7EJ United Kingdom
AU: Kauristie, K
SA41A-03 AF: Finnish Meteorological Institute, P. O. Box 503, Helsinki, FIN-00101 Finland
AU: Ogawa, Y
SA41A-03 AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 Japan
AU: Komada, S
SA41A-03 AF: Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tok 113-0033 Japan
AU: Iwagami, N
SA41A-03 AF: Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tok 113-0033 Japan
AB: The S-310-35 sounding rocket was launched from Andoya, Norway, at 0:33 UT on 13 December 2004, during geomagnetically disturbed conditions in the Dynamics and Energetics of the Lower Thermosphere in Aurora (DELTA) campaign. Rotational temperature and number density of molecular nitrogen (N₂) were observed by a rocket-borne instrument at altitudes between 95 and 140 km. The observed rotational temperature, which is expected to be equal to neutral temperature, is 70-140 K higher than neutral temperature predicted 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 of ~ 500 K are derived from the directions closest to the rocket trajectory and correspond to the rotational temperature measured at an altitude of 120 km. A combination of the all-sky camera images at 557.7 nm from two stations, Kilpisjarvi and Muonio, suggests that the optimum altitude of the aurora arc at the time of the rocket launch was about 120 km. These results show that the neutral temperatures from the ground-based FPI observations are consistent with the in situ rotational temperature observations rather than the MSIS model profile. On the other hand, the observed N₂ number density is much lower than the MSIS model. The proportion of the observed density to the MSIS model value changes with altitude from 30% at 100 km to 90% at 140 km. Such a density reduction is significant for the use of the ion-neutral collision frequency in the EISCAT observation and thereby the estimation of the neutral wind, ionospheric current, and electromagnetic energy transfer rate.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0310 Airglow and aurora
DE: 0350 Pressure, density, and temperature
DE: 0355 Thermosphere: composition and chemistry
DE: 0358 Thermosphere: energy deposition (3369)
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005