Despite it's relatively course resolution, the use of geostationary satellite data to monitor thermal signatures on the surface of the Earth has numerous advantages over aircraft or polar orbiting satellite data. Temporal sampling limitations because of orbit or clouds are not as big of a factor with the geostationary measurements. More importantly, the same viewing geometry is obtained every time measurements are made, eliminating shadowing and anisotropic radiation effects that often plague the interpretation of measurements from other observation platforms. The goal of this research is to show the utility of geostationary satellite data to study land surface temperature variations associated with urban regions. A typical diurnal cycle of LST associated with the urban and rural region of Atlanta is shown in the figure above for a three-day period in September of 1997.
Urban areas are warmer than rural areas both during the day and at night.
These curves indicate a period near sunset where rural LSTs are nearly as warm or warmer than the urban region. This is due to a rapid cooling of the urban surface between maximum insolation and sunset. This is probably due to evapotranspiration from the vegetated surface providing a cooling mechanism for the vegetation canopy. Surface cooling begins shortly after solar noon with urban region initially cooling quicker than rural region. After sunset, the cooling rate trends towards zero at sunrise for both urban and rural regions.