A Radiative Transfer Model for MW Cold and IR Hot Spots of Chang’e and Diviner Observations

The anomalous “hot spots” in infrared (IR) bands on lunar surfaces were discovered earlier in the 1960s. It was then found that those “hot” spots in IR turned out to be “cold” spots at night in microwave (MW) bands observations by Chinese CE-1, CE-2 (Chang'e) radiometers. It was intuitively explained by the thermal properties of a large number of rocks over the cratered surface. In this paper, a radiative transfer layering model of rocks over regolith is presented for the quantitative analysis of the anomalous IR “hot” and MW “cold” spots. First, the physical temperature profiles of the rock/regolith media are derived by solving the 1-D heat conduction equation. Brightness temperatures (TB) of these media in both IR and MW are obtained. Due to large inertia of rocks, its temperature is higher than regolith surface at night and causes IR “hot spots.” However, quickly cooled surface at night reverses the temperature profile of the regolith. Due to the MW penetration, warm regolith beneath the surface without rocks can contribute more TB in comparison of “cold spots” of the rocky surface. Based on the thermo-physical and dielectric parameters of layering rock and regolith media, the quantitative results of our radiative transfer model in both IR and MW bands well match the data of Diviner IR and CE-2 MW-37 GHz.