Solar influence on winter severity in central Europe

Abstract

The last two winters in central Europe were unusually cold in comparison to the years before. Meteorological data, mainly from the last 50years, and modelling studies have suggested that both solar activity and El Nio strength may influence such central European winter coldness. To investigate the mechanisms behind this in a statistically robust way and to test which of the two factors was more important during the last 230years back into the Little Ice Age, we use historical reports of freezing of the river Rhine. The historical data show that 10 of the 14 freeze years occurred close to sunspot minima and only one during a year of moderate El Nio. This solar influence is underpinned by corresponding atmospheric circulation anomalies in reanalysis data covering the period 1871 to 2008. Accordingly, weak solar activity is empirically related to extremely cold winter conditions in Europe also on such long time scales. This relationship still holds today, however the average winter temperatures have been rising during the last decades. © 2012. American Geophysical Union. All Rights Reserved.