Variation in Lunar Regolith Space Weathering Relative to Latitude and Wavelength

Abstract This study examines lunar regolith space weathering as a function of wavelength, terrain type, and latitude using multiple datasets to quantify global and regional trends in surface reflectance and emission. Distinguishing space-weathering effects from bulk compositional controls is essential for interpreting spatial spectral variability and for identifying anomalous surface units. A statistically significant decrease in weathering with increasing latitude is observed in mare regions at all wavelengths analyzed, although the strength of the trend varies with wavelength. The strongest correlation occurs in the far-ultraviolet, consistent with its high sensitivity to space-weathering products such as submicroscopic iron. In the maria, the latitudinal dependence is well described by an equator-anchored cosine function, supporting a solar-zenith-controlled weathering process. Highlands terrains also exhibit statistically significant latitude-dependent behavior in ultraviolet and near-infrared observations, but the pattern is less monotonic and includes structured spatial variability, indicating a more complex interplay among weathering state, composition, and local geologic context. These results show that latitude-dependent space-weathering gradients are globally important but are also modulated regionally, including by longitude. Such gradients may bias spectral interpretations of regolith composition, particularly when applying commonly used compositional algorithms across terrains or spatial scales without accounting for maturity effects. Although terrain-specific approaches for maria and highlands have been proposed, the implications of latitude-dependent weathering have not yet been fully incorporated into compositional modeling or reconciled with interpretations based on optical maturity.