Using MODIS LST to Estimate Minimum Air Temperatures at Night

Satellite-derived land surface temperature (LST) is studied for the purpose of understanding regional LST dependency and variability, and its relationship to corresponding, site-specific air temperature. LST is highly correlated with surface-air temperature although it differs depending on land surface characteristics, terrain, and atmospheric conditions on a diurnal and seasonal scale. The high temporal resolution of the Geostationary Operational Environmental Satellite (GOES) -12 sounder is used to compare the diurnal cycles of LST and surface-air temperature. The minimum for both temperatures occurs near sunrise and LST is found to agree closely with surface-air temperatures a period of hours before sunrise on clear sky nights. The Moderate Resolution Imaging Spectroradiometer (MODIS)-derived LST renders more horizontal temperature structure - with its high spatial resolution (1km at nadir) compared to the GOES-12 sounder (10 km). Nighttime MODIS LST is compared to minimum surface-air temperatures for a number of case study days. Linear regression equations are used to estimate air temperature at the resolution of the MODIS data.