厚度对月壤微波辐射亮温的影响

基于嫦娥系列卫星微波辐射计数据的月壤厚度反演是中国月球科学研究的重要目标之一。基于辐射传输方程，数值模拟了不同频率、（FeO+TiO₂）含量和表面温度条件下厚度对月壤微波辐射亮温的影响；基于嫦娥二号卫星微波辐射计（Chang’E Lunar Microwave Sounder,CELMS）数据，结合Apollo 计划获取的月壤厚度资料及其他月壤厚度资料，系统分析了厚度对CELMS观测数据的影响。结果表明：频率、（FeO+TiO₂）含量、表面温度对亮温的影响远大于厚度对亮温的影响，是基于CELMS数据进行月壤厚度反演的重要影响因素；低频、低（FeO+TiO₂）含量、低温条件下，厚度对CELMS数据的影响最大；利用3 GHz、凌晨时刻的CELMS数据进行月陆地区月壤厚度反演可行。研究结果对基于嫦娥系列卫星CELMS数据的月壤厚度反演具有重要参考意义。

Influence of layer thickness on microwave emission of lunar regolith

The collection of microwave radiometer data (CELMS data) from Chang'E-2 satellite makes it possible to study the influence of the layer thickness on the microwave thermal emission of the lunar regolith. In this paper, the raidative transfer simulation is employed to study the change of the brightness temperature with the lunar regolith layer thickness in different frequency, (FeO + TiO₂) abundance and surface temperature. The results indicate that the change of the simulated brightness temperature with the thickness is apparent to certain depth in low frequency and the low (FeO+TiO₂) abundance, while the correspondence between the brightness temperature and the thickness is missing if the regolith is thick enough. The influences from the regolith layer thickness is much weaker than that from the frequency, the (FeO+ TiO₂) abundance and the surface temperature, which are crucial factors to invert the lunar regolith layer thickness with the CELMS data. Then the influence of the thickness on the microwave thermal emission from the lunar regolith is analyzed with the CLEMS data from Chang'E-2 satellite and the measurements from Apollo projects. The results indicate that correlation between the thickness and the microwave thermal emission of the lunar regolith is weak. The microwave emission of the lunar regolith will be a bit more heavily affected by the regolith layer thickness if the observation is in low frequency, the surface temperature is low and low (FeO+ TiO₂) abundance of the regolith is low. Moreover, the simulated brightness temperature agrees well with the observed CELMS data in lunar highlands along the Moon Equator in 3 GHz, while it is much bigger at noon or much smaller at dawn than the observed CELMS data in lunar maria. It is feasible to retrieve the lunar regolith layer thickness in lunar highlands using the CELMS data in 3 GHz on dawn. The research is essential for the inversion of the lunar regolith parameters with the microwave radiometer data from Chang'E satellites.