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WIBIX - WInter Baltic climate IndeX

Climatic turning points and regime shifts in the Baltic Sea region: the Baltic winter index (WIBIX) 1659-2002.

(WIBIX time series subsequently extended till 2019 by E. Hagen)

The derived climate index is based on monthly values of the first principal component of (i) winter anomalies (January - March) of air pressure difference between Gibraltar and Reykjavik to describe the North Atlantic Oscillation, (ii) sea level anomalies of Landsort (Sweden) to characterise the filling level in the Baltic Proper, and (iii) maximum Baltic ice cover to include the influence of continentally dominated alignments of atmospheric centres of action (1897-2002). Resulting time coefficients were regressively completed by corresponding winter anomalies in air temperature over central England (1659-1896). The power spectrum of the obtained index (WIBIX 1659-2002) exhibits five significant quasi cycles (2.2, 3, 6, 8, and 14 years), but also suggests periods of about 40 and 100 years. Severe (continental, WIBIX < 0) and mild (maritime, WIBIX > 0) winter types alternate and associated turning points characterise regime shifts affecting the ecosystem.

Download WIBIX data here:  


Baltic Winter Index (Hagen & Feistel, 2005), extended till 2019 by E. Hagen: