Thursday, August 1, 2013

New satellite dataset finds global temperatures decreased from 1982-2006

A new peer-reviewed paper published in Energy & Environment analyzes 24 years of data from the European Meteosat weather satellite and finds global temperatures decreased over the period 1982-2006. According to the authors, 
"Our observations point to a decrease in planetary temperature over almost the entire hemisphere, most likely due to an increase of cloudiness." 
"The cloud filtered temperature change patterns, in figure 2c, indicate that the largest decrease occurs in the more cloudy regions of the hemisphere: the tropics and the temperate zones, while in the desert belt the temperature decrease is much smaller. This suggests that cloudiness changes could be the mechanism behind the observed global cooling since 1982: an increase in cloudiness would decrease global radiation and increase rainfall and evapotranspiration. Both effects tend to decrease the surface temperature."
Full paper available here

Meteosat Derived Planetary Temperature Trend 1982-2006 

Andries Rosema1, Steven Foppes1, Joost van der Woerd1
1EARS Earth Environment Monitoring Ltd., Delft, the Netherlands Kanaalweg 1, 2628 EB Delft, the Netherlands


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.

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