Regional co‐variability and teleconnection patterns in surface solar radiation on a planetary scale

Abstract

AbstractThe spatial and temporal distribution of the downward solar radiation (DSR) at the Earth's surface, which is a key parameter for the Earth‐atmosphere climate system, is studied on a global scale by applying the multivariate statistical method of factor analysis (FA) on mean monthly DSR values for the period 1984–2000 for winter and summer. DSR fluxes have been computed with a physical deterministic radiation transfer model, which uses satellite and reanalysis climatological input data. FA objectively groups grid points with common temporal variability of solar radiation, identifying areas with characteristic solar radiation variability and revealing teleconnection patterns. The globally distributed DSR exhibits strong variability and can be represented by about 30 factors (sub‐areas) explaining approximately 85% of the total variance. The main factors are located in the tropical Pacific (El Niño Southern Oscillation), the northern Pacific (Aleutian low), desert areas (Africa, Middle East, and Australia), and oceanic areas (storm track zone around 60°S). Furthermore, some of these areas are teleconnected indicating common DSR variability in remote places of the Earth. The primary physical parameter for the co‐variability of surface solar radiation is found to be cloud cover. The time series of the factor scores (solar radiation) exhibit features associated with natural climatic phenomena (e.g. NAO, ENSO), thus revealing that DSR might be considered as an indirect indicator for these phenomena. On the other hand, DSR determines these phenomena through its effects on major climate parameters such as surface temperature or evaporation, thus playing a key role in their formation and explanation. Finally, our analysis revealed some statistically significant trends of solar radiation, for example, a reduction in the northern Pacific and an increase in tropical and subtropical regions, which are important for global dimming/brightening and associated surface warming of the Earth. Copyright © 2009 Royal Meteorological Society