两分两至点热层大气密度变化

 热层大气受太阳辐射的影响，其变化与光照时间长短密切相关，在春分、秋分、夏至、冬至期间呈现出不同的特点。通过在中国低轨道航天器上装载大气密度探测器，获得在轨原位探测数据，分析大气密度在两分两至点时的变化关系。结果表明，春分和秋分（两分点）期间全球热层大气密度随纬度对称性变化，但夏至和冬至（两至点）期间则呈现出全球热层大气密度的南北半球不对称性变化；两至点期间南北半球分别处于夏半球和冬半球，在南北高纬地区（纬度80°附近）670 km上空热层大气密度存在显著差异，探测值表示出3~3.6倍的差异，而在560 km高度上探测到两者差异可高达13倍左右，不对称程度与高度和纬度有关；探测值与模式值比较表明，模式值对冬夏半球上空热层大气密度差异变化显著响应不足。

Variations of thermospheric density during equinox and solstice

The thermospheric neutral density sees a strong variation during equinoxes and solstices due to the solar insolation variation. The long-term continual data from Chinese Atmospheric Density Detector installed on the satellite are used to study this variation, The main results of this study are that the thermospheric density has an obvious symmetry around March equinox and September equinox; the thermosphere density has an obvious asymmetry around June solstice and December solstice; the variations have an obvious hemispheric asymmetry in high latitude (around 80 degrees); the proportion of the atmospheric density is 3~3.6 times at the height of 670 km, 13 times at the height of 560 km; the latitude and the altitude contribute to this asymmetry; the comparison of the measured data and the NRLMSISE00 data shows that the NRLMSISE00 data cannot fully respond to the summer and winter hemisphere atmospheric density variations.