VARIABILITY AND TREND IN THE ANNUAL SOLAR IRRADIATION DETERMINED FROM METEOSAT SATELLITE DATA

摘要

We present a study of the variability of the annual solar irradiation and the long-term trend in solar radiation, based on the retrieval of solar radiation data from satellite images. For Europe and Africa the data from the METEOSAT satellites comprise the period 1983-2013 while for Asia the eastern METEOSAT satellites have been used for the period 1999-2014. Results show that over most desert areas the year-to-year variability is low, with a relative standard deviation of 1% or less. Temperate climates show higher variability at 3-5%, while the highest variability is found in mountain areas in Europe and Asia where the standard deviation may reach 7-8%. An analysis of the long-term trend in solar radiation shows that in most areas the calculated trend is not statistically significant at the p＜0.05 level. Areas showing a significant trend are most of Eastern Europe (+2 to 3% per decade), Tropical West Africa (-1 to -2 %/decade) and parts of Central Asia (up to +5% per decade). One weakness of the present study is that long-term averages of the aerosol optical depth have been used whereby variations and trends in aerosols have not been taken into account.