Meteosat Derived Planetary Temperature Trend 1982–2006

Abstract

24 year of Meteosat hourly thermal infrared data have been used to study planetary surface temperature change. Thermal infrared radiation in the 10.5–12.5mm spectral window is not affected by CO2 and only slightly by atmospheric water vapor. Satellite thermal infrared data have been converted to brightness temperatures as prescribed by Eumetsat. Hourly brightness temperature images were then composed to corresponding noon and midnight temperature data fields. The resulting data fields were cloud filtered using 10, 20 and 30 day maximum temperature substitution. Filtered data were subsequently averaged for two 10 yearly periods: 1986–1995 and 1996–2005. Finally the change in brightness temperature was determined by subtraction. In addition nine locations were selected and data series were extracted and studied for the period 1982–2006. Our observations point to a decrease in planetary temperature over almost the entire hemisphere, most likely due to an increase of cloudiness. Two small areas are found where a considerable temperature increase has occurred. They are explained in terms of major human interventions in the hydrological balance at the earth surface.