Qualitative Verification of CE-2's Microwave Measurement: Relative Calibration Based on Brightness Temperature Model and Data Fusion

The calibration quality of the Chang'E-2 (CE-2) microwave radiometer (MRM) and the accuracy of brightness temperature (TB) data should be adequately addressed. The quality of CE-2 MRM data can be demonstrated by the analysis and simulation of TB data with the microwave transfer model and by the relative comparison between the TB and other data sets. To calibrate the TB data in a relative way, we calculated the variation of TB with respect to the latitude over certain typical regions theoretically. Three types of areas in the Moon, including the old crater, the fresh crater, and the Apollo region, are chosen as examples. A detailed method incorporating the topographic effect is employed to compute the TB. The Lunar Reconnaissance Orbiter's Diviner infrared measurement is used to ensure the accuracy of the simulated physical temperature. The consistency of the TB undulation between simulations and observations along the profile of these regions verifies the reasonability of CE-2's TB data partly. Our simulation also confirms the topographic effect of sloping walls at the crater rims on the solar heat flux received per unit surface area and reproduces the TB undulation observed by CE-2. Rock abundance and topography data are used for qualitative comparison with the CE-2 TB data. General similarity between the diurnal TB difference and the altitude profile over most craters and the similarity between the diurnal TB difference and the rock abundance profile over fresh craters can prove the relative qualification of CE-2 MRM data to a certain degree.