Climate information imprinted in oxygen-isotopic composition of precipitation in Europe

In this study we analyze the interannual variability of the oxygen-isotopic composition of winter precipitation (δ18Oprecδ18Oprec) over Europe and investigate its related climate information. For this purpose we compare winter temperature, precipitation and δ18Oprec modeled by the atmospheric general circulation model ECHAM5-wiso with different observational datasets over Europe. In general the model and data results are very similar for the present-day climate and the modeled δ18Oprecδ18Oprec is matching the Global Network of Isotopes in Precipitation station data. ECHAM5-wiso only slightly underestimates the temperatures over Europe (mean difference ~ 0.4 °C). The mean European precipitation amount is very similar (~ 85 mm/month), however in central western Europe the modeled precipitation is overestimated by up to 30 mm/month. We also evaluate the large-scale circulation associated with the regional δ18Oprecδ18Oprec values. By correlating the North Atlantic Oscillation (NAO) index to modeled δ18Oprecδ18Oprec fields, we show that the NAO pattern is most pronouncedly imprinted in δ18Oprecδ18Oprec over central western Europe, consistent with observations. We demonstrate for an example location near a stalagmite site in central Germany, how local isotope-related climate variables are related to large-scale European climate variability. We find that, in both the model results and the data, present-day winter variability of local δ18Oprecδ18Oprec is strongly related to atmospheric circulation (remote sea-level pressure fields) and much less to the local and remote temperature or precipitation fields. The simulated correlation pattern resembles the NAO pattern, but is tilted to the east due to the combined effect of temperature and precipitation.

► European simulated temperature, precipitation and d18Op are comparable to data.
► NAO variability is strongly imprinted in d18Op and temperature over central Europe.
► In contrast, precipitation has a high correlation to NAO over north and south Europe.
► Local d18Op is a regionally integrated signal of several climate variables.