Aspects of thermal modeling using digital terrain models

Abstract

Context. Our thermal model is adapted and extended in this study. Specifically the aspect of handling indirect radiation, the solar limb darkening effect, and depth profiles are addressed. Aims. Our goal is to improve the existing thermal model to handle terrain scattering and re-radiation in an adaptive way. In addition, we aim to change previously fixed and manually chosen discretization of the solar limb darkening effect and depth profile to be adaptive and applicable for various planets and purposes. Methods. The temperature was modeled based on digital terrain models (DTMs) using data of the Mercury Laser Altimeter (MLA). New implementations to handle terrain scattering and re-radiation were introduced using level-of-detail techniques. The solar disk was discretized into a variable number of rings and the depth profile was introduced as an exponential function for which the number of nodes and the maximum depth can be chosen. Results. We present results for the ideal window size and degree of level-of-detail for thermal studies of the Hermean north pole. Further we show that the previous discretization of the solar limb darkening effect proved insufficient for Mercury, and we updated the implementation accordingly. Similarly we improved the implementation for the depth profile. For the first time, we derived depth-to-ice, as well as average and maximum temperature maps based on thermal modeling of the complete north polar MLA DTM.