Large-scale atmospheric circulation patterns control the stable isotopic composition of precipitation in SE Europe

The stable isotopic composition of precipitation at any given site is strongly influenced by global, regional and local factors. Among these, geographic position (latitude, altitude, distance form moisture sources) and climatic conditions (air temperature; precipitation types, patterns and amount; relative humidity) are considered as being the most important. However, mounting evidence points towards larges-scale atmospheric circulation patterns as having a role that offsets and/or masks some (or most) of these factors. In this paper, we use modern and palaeo data to show that in regions with complex interactions between climatic influences and thus highly variable moisture sources, such patterns are the main controlling factors on the distribution of δ¹⁸O and δ²H in precipitation. Our study area is SE Europe, where interactions between the North Atlantic Oscillation, the Siberian High, the Scandinavian Pattern (and several other, regional patterns) results in advection of moisture from the Atlantic and Arctic Oceans; the Mediterranean, Black and Caspian Seas; and interior Asia, all with distinctive δ¹⁸O and δ²H values, that are strongly imprinted in that of local precipitation. In turn, these are registered by paleoarchives (cave ice, speleothems, tree ring cellulose) resulting in ambiguous signals that can be interpreted as changes in local/regional climatic conditions, rather than changes in the source of moisture. We discuss how δ¹⁸O and δ²H (and the secondary d-excess parameter) values in precipitation are linked to the varying strength of the main atmospheric circulation patterns and how regional sedimentary archives register them and further, how we can reconstruct past changes in their dynamics.