Effects of Temporal Sampling Interval on the Moon-Based Earth Observation Geometry

Abstract

The effects of temporal sampling interval on the moon-based earth observation geometry are analyzed in this study based on three observation angles, namely viewing zenith angle, solar zenith angle, and relative azimuth angle. According to the definitions of these three angles, the calculation method for these angles and their variations between adjacent temporal samplings are deduced. Furthermore, the effects of the different positions of the lunar surface on the observation angles are derived. The results show that the variations of the nadir point and subsolar point determine the variations of the viewing zenith angle and solar zenith angle, respectively, whereas the relative azimuth angle needs to consider the relative variations of the moon-based platform's nadir point and the subsolar point. By evaluating the variations of these three observation angles, it is found that the effects of the temporal sampling interval will have significant impacts on the relative azimuth angle of the observed points at mid-low latitude regions, especially near the regions of the moon-based platform's nadir point and the subsolar point. In conclusion, the observation angles can characterize the moon-based earth observation geometry, and enlarging the temporal sampling interval will lead to the obvious impacts on the observation geometry in the mid-low latitude regions, especially the loss of the sampling of the relative azimuth angle.