The thermal state of the North Atlantic and macro-circulation conditions in the Atlantic-European sector, and changes in sunshine duration in Central Europe

Abstract

This article explains the reasons for the long-term variability in sunshine duration (SD) in Central Europe. It presents a recently discovered mechanism regulating changes in sunshine duration, not described so far in the literature. The periods of global dimming and global brightening were linked with changes in the annual frequency of the macrotypes of the middle-tropospheric circulation and the variability in the surface component of the thermohaline circulation in the North Atlantic (NA THC). On the basis of the totals of annual sunshine duration from the years 1951–2015 from 21 stations located in the Netherlands, Germany, Denmark, Poland, Switzerland, Austria, the Czech Republic and Slovakia, it was shown that changes in NA THC account for onethird of the variability in sunshine duration, while changes in the frequency of macrotypes W and E, forced by the changes in NA THC, each separately account for about 26 and 22% of the variability in the totals of annual sunshine duration in Central Europe.