Land Surface Temperature and Surface Air Temperature in Complex Terrain

Land surface temperature (LST) is a fundamental physical property relevant to many ecological, hydrological, and atmospheric processes. There is a strong relationship between LST and near surface air temperature (T_air), although the two temperatures have different physical meaning and responses to atmospheric conditions. In complex terrain, these differences are amplified; yet it is in these environments that remotely sensed LST may be most valuable in prediction and characterization of spatial-temporal patterns of T_air due to typical paucity of meteorological stations in mountainous regions. This study presents an analysis on the suitability and limitations of using LST as a proxy or an input variable for predicting T_air in complex mountainous topography. Explicitly, we investigated the influence of key environmental, topographic, and instrumental factors on the relation between LST and measured T_air in two mountainous ecoregions of Nevada. The relation between LST and T_air was found to be strongest during late summer and fall, and weakest during winter and early spring. Increasing terrain roughness was found to diminish the relation between between LST and T_air. There was a strong agreement between nighttime T_air lapse rates and LST lapse rates. Given the inadequacy of several gridded T_air products in capturing minimum temperature cold-air pooling and inversions, using LST as an input variable in the interpolation process would enhance capture of temperature inversions in grid-ded data over complex terrain. Crucially, the relationship between LST and T_air did not differ significantly across the two distinct mountainous ecoregions.