Influence of meteorological patterns on global dimming and brightening in Europe
Abstract
Decadal scale variability of surface insolation, commonly referred to as global dimming and brightening, is often described as geographically homogenous and an aerosol driven phenomenon. On shorter time scales, the presence and amount of clouds are the most important factors determining atmospheric transmission of solar radiation. At mid-latitudes, cloud distribution is heavily influenced by large scale meteorology. It is therefore a reasonable assumption that changes in weather patterns may affect long term trends in surface insolation. In this case, dimming and brightening may exhibit a regional rather than global pattern. In this work we study the variability of meteorology in Europe and its effect on surface insolation on monthly to decadal time scales. As a measure of large scale meteorology, we use Hess and Brezowsky's Grosswetterlagen (GWL), a collection of 29 European weather patterns subjectively assigned to each day from 1881 to 2009. Each GWL is characterized by a cyclone or anticyclone over some part of central or northern Europe. The monthly frequency of European weather patterns varies significantly on time scales from 10-30 years. Comparing the GWL patterns to cloud observations from the Extended Edited Cloud Reports Archive (EECRA), we find that each GWL has an associated cloud pattern. Trend analysis of surface insolation data from the Global Energy Balance Archive (GEBA) shows that there are regional differences in global dimming and brightening. In many of the European GEBA sites, a large part of the monthly solar radiation variability can be explained by a linear combination of GWL patterns. In some locations, the long term trends can also be partly explained by changes in weather patterns. It is likely that in parts of Europe, much of the global dimming and brightening signal is a consequence of fluctuations in meteorological patterns, rather than due to changing aerosol loadings.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.A23A0186P
- Keywords:
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- 1616 GLOBAL CHANGE / Climate variability;
- 1650 GLOBAL CHANGE / Solar variability;
- 3305 ATMOSPHERIC PROCESSES / Climate change and variability;
- 9335 GEOGRAPHIC LOCATION / Europe