中文摘要：

为了解中国北纬40°上空过渡流区大气月平均状态,使用热层-电离层-中间层大气能量与动力/宽频辐射计大气探测卫星资料,选取北京和酒泉上空50～110km高度2003-2014年共计12a的温度和密度数据,采用Lomb-Scargle谱分析方法分析了两站资料的周期特征、温度和密度周期随大气高度的变化特征,以及太阳活动对过渡流区的影响。结果表明：过渡流区的大气状态随经度变化很小,大气温度随时间变化呈现显著的4个月震荡和年震荡,自然年内温度的4个月震荡在过渡流区底层和顶层具有同位相特征,在中层为反位相特征;大气密度随时间存在半年变化和年变化特征,90km以下以年变化为主,90km以上年变化和半年变化同时存在;过渡流区上层温度和密度受到太阳活动的影响显著,强弱随月份变化。

英文摘要：

To research the monthly averaged atmospheric conditions in the transition flow region in 40°N of China.The thermosphere ionosphere mesosphere energetics and dynamies（TIMED）/sounding of the atmosphere using broadband emission radiometry（SABER）data were used for the first time in this paper.The data of temperatures and densities in Beijing and Jiuquan between 2003-2014 were selected.The spectral analysis method of Lomb-Scargle was used to extract the periodicity features.Results show that conditions in the transition flow region has a very little change along the longitude.Spectral analysis indicate that the temperatures in the transition flow region have a notable 4-month period as well as a one-year period,and a further analysis indicates that the 4-month period shows the same phase in the bottom of the region as well as in the upper region,and a anti-phase in the middle layer.The densities have a half-year period and a one-year period.Both periods exist above 90 km and only the one-year period is obvious below 90 km.An external forcing on temperature and density from solar activity exists in the upper transition flow region,and this external forcing varies with month.