被动微波遥感具有全天候工作的能力, 但是在不同的大气状态下被动微波遥感受大气的影响不同。 为了研究大气对高级微波扫描辐射计AMSR-E (advanced microwave scanning radiometer-earth observing system)入瞳亮温的影响, 分别采用晴空和典型层云大气数据作为微波辐射传输模型的输入, 进行大气微波辐射信号的模拟工作并分析大气的影响。 结果表明晴空下大气水汽是引起大气辐射的主要因素, 晴空条件下大气对典型被动微波传感器低频的(<18.7 GHz)透过率大于0.98, 在整个辐射传输过程中可以忽略不计。 36.5和89 GHz的大气透过率在晴空下分别为0.896和0.756, 在用微波高频通道进行陆表参数反演时需进行大气水汽影响的校正; 云覆盖条件或者阴天情况下云中液态水是引起大气辐射的主要因素, 典型层云覆盖下大气的透过率在10.7, 18.7和36.5 GHz分别为0.942, 0.828和0.605。 与晴空相比, 由层云中液态水引起的大气下行辐射的增量在36.5 GHz最大达到75.365 K。 表明在云覆盖时大气影响的校正过程中云层的影响是校正重点。 最后利用大气探空数据计算了内蒙古海拉尔地区2013年夏季7月份的大气透过率, 结果显示C、 X波段的大气透过率接近1, 89 GHz受水汽影响较大, 其地球表层大气透过率不超过0.7。 在内蒙古海拉尔地区, 夏季大气透过率具有较为稳定的值, 但是随着局部水汽的变化具有0.1左右的波动。

Passive microwave remote sensing offers its all-weather work capabilities, but atmospheric influences on satellite microwave brightness temperature were different under different atmospheric conditions and environments. In order to clarify atmospheric influences on Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E), atmospheric radiation were simulated based on AMSR-E configuration under clear sky and cloudy conditions, by using radiative transfer model and atmospheric conditions data. Results showed that atmospheric water vapor was the major factor for atmospheric radiation under clear sky condition. Atmospheric transmittances were almost above 0.98 at AMSR-E’s low frequencies (<18.7 GHz) and the microwave brightness temperature changes caused by atmosphere can be ignored in clear sky condition. Atmospheric transmittances at 36.5 and 89 GHz were 0.896 and 0.756 respectively. The effects of atmospheric water vapor needed to be corrected when using microwave high-frequency channels to inverse land surface parameters in clear sky condition. But under cloud cover or cloudy conditions, cloud liquid water was the key factor to cause atmospheric radiation. When sky was covered by typical stratus cloud, atmospheric transmittances at 10.7, 18.7 and 36.5 GHz were 0.942, 0.828 and 0.605 respectively. Comparing with the clear sky condition, the down-welling atmospheric radiation caused by cloud liquid water increased up to 75.365 K at 36.5 GHz. It showed that the atmospheric correction under different clouds covered condition was the primary work to improve the accuracy of land surface parameters inversion of passive microwave remote sensing. The results also provided the basis for microwave atmospheric correction algorithm development. Finally, the atmospheric sounding data was utilized to calculate the atmospheric transmittance of Hailaer Region, Inner Mongolia province, in July 2013. The results indicated that atmospheric transmittances were close to 1 at C-band and X-band. 89 GHz was greatly influenced by water vapor and its atmospheric transmittance was not more than 0.7. Atmospheric transmittances in Hailaer Region had a relatively stable value in summer, but had about 0.1 fluctuations with the local water vapor changes.