Earth Planets Space, Vol. 56 (No. 2), pp. 249-258, 2004
H. Takahashi1, T. Nakamura2, K. Shiokawa3, T. Tsuda2, L. M. Lima1, and D. Gobbi1
1Instituto Nacional de Pesquisas Espaciais, 12245-970 São José dos Campos, SP, Brazil
2Radio Science Center for Space and Atmosphere, Kyoto University, Uji, Kyoto 611, Japan,
3Solar-Terrestrial Environment Laboratory, Nagoya University, Toyokawa 442-8507, Japan
(Received September 15, 2003; Revised February 18, 2004; Accepted February 19, 2004)
Atmospheric density and pressure in the upper mesosphere-lower thermosphere (MLT) region, around 90 km, are inferred from the meteor trail ambipolar diffusion coefficients, D, and simultaneously observed airglow O2b rotational temperatures. For the present study simultaneous observation data from the meteor radar and SATI imaging spectrometer taken at Shigaraki MU radar observatory (34.9°N, 136.1°E) were used. From the 18 winter nights of data, it is observed that in most of the cases nocturnal variation of the O2 temperature has a good correlation with D at 90 to 92 km. The inferred densities at 90 km showed a negative correlation with temperature variation, suggesting a constant pressure process. The O2 emission intensity shows a good correlation with the temperature, and negative correlation with the density variation. The OH rotational temperature and D at 87 km also showed similar results to the case of the O2 temperature.
Key words: Airglow, meteor trail, temperature, density, pressure.