Scales of temporal and spatial variability of midlatitude land surface temperature

Scales of temporal and spatial variability of clear-sky land surface temperature (LST) in middle latitudes are empirically evaluated using data from satellite and land surface observations. We consider separately the time-dependent expected value, its spatial variations, weather-related temporal and spatial anomalies, and errors of LST observation. Seasonal and diurnal cycles in the time-dependent expected value of LST are found to be the main components of temporal variations of clear-sky LST. The scale of spatial variability in the expected value of LST is found to be much smaller than the scale of spatial variability of the weather-related signal. The scale of temporal autocorrelation of weather-related LST variations is found to be in a good agreement with our earlier preliminary estimate and equal to 3 d, which corresponds to the time scale of weather system variations. This weather-related signal in clear-sky LST is statistically the same as in surface air temperature (SAT) observations at regular meteorological stations. The scale of spatial autocorrelation of weather-related LST variations exceeds 1000 km, which is the spatial scale of synoptic weather systems. These estimates provide us with a basis for better understanding and interpretation of LST observations from past, current, and future geostationary satellites and polar orbiters.