Stable isotopic signature of precipitation under various synoptic classifications

The relative abundance of naturally occurring heavy isotopes of oxygen and hydrogen in atmospheric water depends on several factors, along the course from the place of origin to its ultimate collection either as condensate vapour or in the form of precipitation. Regional, meso and local scale atmospheric processes, influence the final isotopic signature of a precipitation event. Apparently, many of the factors controlling the isotopic composition of precipitation occurring over an area are correlated and to a large extent, depend upon the synoptic circulation patterns and the associated weather types prevailing over the area. As a result synoptic classification can be a useful tool in the study of the isotopic composition of precipitation and through that in the study of the water cycle in the atmosphere and the reconstruction of past climatic conditions. In that context several synoptic classification schemes provided under the COST733 action were applied on event-based isotopic data from four sites within the domain 7–30E, 34–49N. Many schemes succeeded in providing distinguishable isotopic signatures for the respective synoptic classes and an initial assessment of the relative performance of the various classification methods as well as different number of categories used was made possible.