Stable isotope composition of precipitation in Germany in context to current climate patterns and recent activities of the German Isotope Network (GIN)

The stable isotope composition of precipitation (²H, ¹⁸O) in Germany is mainly affected by temperature and humidity conditions at the moisture source and dominating precipitation processes (e.g. altitude, continental, seasonal effects). Continuous observations of precipitation stable isotope patterns in high spatial and temporal resolution allow a reconstruction of source areas and an interpretation of dominating processes. In Germany, precipitation monitoring organized by the Federal Institute of Hydrology (BfG) started in the mid-1970s. Today, a monitoring network for monthly analysis of water isotopes (GIN) is active with more than 30 stations. Currently, the Federal Institute for Geosciences and Natural Resources (BGR) is analyzing stable isotope composition from 27 stations; for 19 of those stations time series of more than 10 years are available.

For Germany, most dominating stable isotope effects in precipitation are a seasonal and altitude effect, but also a continental effect is visible from delta¹⁸O vs. delta²H plots. Comparing precipitation of different sites and altitudes in Germany reveal topographical patterns. Interestingly, time series from the recent years indicate influence of extending dry and hot summers. Further, it is obvious that the maintenance of such a monitoring network requires lots of effort, also in reducing measurement uncertainties and establishing inter-laboratory comparisons within the GIN network community.