Estimating surface air temperatures, from Meteosat land surface temperatures, using an empirical solar zenith angle model

Temperature values derived from Meteosat are an indication of emitted long- wave radiation, and are not a true indication of ambient air temperature. T he authors believe that Solar Zenith Angle (SZA) can be used as a proxy for solar energy reaching the ground surface, and its subsequent effects upon the land surface temperature detected by Meteosat. Raw satellite temperatur es often overestimate the actual screen temperature during the day, and und erestimate at night. By using a statistical model which relates Meteosat an d WMO screen temperature deviations, and SZA values, it has been possible t o generate a correction algorithm which minimizes these differences. The al gorithm generates a new proxy value, being a simulated ambient (screen) air temperature. The algorithms achieve an accuracy of within 3 degrees C for over 70% of the Meteosat temperatures processed. The operational use of thi s algorithm requires only the raw Meteosat temperature value, and the SZA. Such temperature corrections are useful for a wide range of environmental m onitoring applications. An example is in the field of vector-borne disease modelling which requires proxies for temperature across large regions, and where more conventional meteorological stations are inadequate.