我國華衛一號(現已更名為福衛一號)上的電離層電漿電動效應儀，自1999年起，已觀測五年多在電離層頂部的離子資料〈透過這豐富的資料庫，我們已建立隨時間、季節與太陽週期變化的全球離子溫度分布〈從過去研究中，在美國國防氣象衛星上，曾觀測在晚上冬半球的低緯度區塊會出現離子溫度脊，而離子溫度谷出現在夏半球靠近地磁赤道處．透過華衛一號資料分析，可得出相似結論．但由於華衛一號的飛行高度較低，一般認為氧離子的絕熱壓縮與膨漲的效應會不明顯．此外，我們有溫度分布隨現地時間變化的資料，可進一步研究離子溫度脊與溫度谷的消長情形．透過 SAMI2 模式，將可與現有的離子觀測資料做比對，來確定離子溫度脊與溫度谷的生成機制．同時透過華衛一號的觀測結果，可協助改良 SAMI2 模式． Average ion parameters at 600 km altitude have been constructed with measurements from the Ionospheric Plasma and Electrodynamics Instrument (IPEI) onboard the first satellite of Republic of China, ROCSAT-1, orbiting with a 35o inclination during 1999-2004. Quiet-time ion temperature distributions in the midnight sector are investigated for different local times and seasons during the solar maximum year of 2000. In comparison to previous study [Venkatraman and Heelis, 2000] with Defense Meteorological Satellite Program (DMSP) satellite, we find out similarities in global ion temperature patterns for different seasons even though the DMSP satellites fly at higher altitude. At solstices, temperature crests and troughs are located in the winter hemisphere and near the dip equator (close to summer hemisphere), respectively. Both the maximum in the temperature crests and the minimum in the temperature troughs are located in a longitudinal region of negative magnetic declination (South Atlantic region) during the June solstice and in the longitudinal region of positive magnetic declination (North Pacific region) during the December solstice. Such variations are attributed to adiabatic compressions and expansions caused by field-aligned ion flow patterns, which are possible to identify through the ROCSAT measurement. Meanwhile, in our observations, the temperature crests are greatly reduced in/after the 2100-2200 LT but still exist in later hours. However, the temperature troughs last for all night. These could be resulted from the efficiency of adiabatic compression/expansion processes, which would be changed with O+-H+ transition height. The O+-H+ transition height could be verified by ROCSAT measurement and is expected to be lower at low and middle latitudes in the winter hemisphere but is higher at the dip equator. These signatures will be resolved with the SAMI2 model. In return the study can help improve the SAMI2 model and clarify the physical mechanisms to produce the temperature crests and troughs in the midnight sector. 研究期間：9908 ~ 10007
