Thermospheric Nocturnal Wind Climatology Observed by Fabry-Perot Interferometers over the Asia-Oceania Region

Abstract

 This study shows the horizontal structure of climatology of thermospheric nocturnal winds at a height of approximately 250 km in the Asia-Oceania region for the first time using observations made with Fabry-Perot interferometers (FPIs; optical wavelength of 630.0 nm). The FPIs used in this study were located at Shigaraki (Japan, 34.8°N, 136.1°E), Chiang Mai (Thailand, 18.8°N, 98.9°E), Kototabang (Indonesia, 0.2°S, 100.3°E), and Darwin (Australia, 12.4°S, 131.0°E). The observation data underwent quality control that involved consideration of cloud information, wind speed value, and standard deviation of results obtained from synchronous fringe images; approximately 30 % of the observation data from all the four stations were deemed suitable for use. The nocturnal diurnal changes at Shigaraki according to the local solar time were generally consistent with changes in China at similar latitudes, although the amplitudes were slightly different. All four stations showed the continuous flow pattern of the nocturnal diurnal wind in each season. The Chiang Mai and Darwin stations observed seasonal/diurnal changes similar to those observed by stations at similar latitudes on the North and the South American continents. Although there were fewer samples for Chiang Mai, Kototabang, and Darwin in the rainy season compared to that for Shigaraki, the seasonal climatology reported here can be used to provide a background long-term average status for describing anomalous events and extremes having different causes.