Underlying Climate Controls in Triple Oxygen (16 O, 17 O, 18 O) and Hydrogen (1 H, 2 H) Isotopes Composition of Rainfall (Central Pyrenees)

Studies of rainfall isotopic composition in the Iberian Peninsula are scarce, and to date, none of them have provided analyses of the triple oxygen isotopes, preventing from the complete understanding of current atmospheric processes in this region. We investigate the rainwate rδ17O,δ18O, an dδD and derived parameters 17O-excess and d-excess ina mountain site in the Central South Pyrenees (Villanúa, Huesca, Spain) to identify themain factors (regional and local) controlling the isotopic composition of precipitation atevent scale. The samples were collected on a rainfall-event basis during 2 years (fromJuly 2017 to June 2019), and meteorological variables [temperature, relative humidity (RH), and rainfall amount] were monitored at the sampling site. The δ17O, δ18O, and δD values were higher during summer and lower during the rest of the year. In contrast, the17O-excess and d-excess were lower during summer and higher during the remaining months. We found that the isotopic parameters are weakly correlated with rainfall amount during each event, but they strongly depend on changes in air temperature and moderately on RH. We consider other factors affecting the isotopic composition of rainfall events that resulted to have an important role, such as the influence of the moisture source and trajectory throughout the variations in the synoptic pattern during rainfall events. This dataset can be useful for further comprehensive atmospheric andhydrological studies, with application to paleoclimatic investigations.
This work was supported by the Spanish Governmenta nd the European Regional Development Funds [projects CGL2016-77479-R (SPYRIT) and PID2019-106050RB-I00 (PYCACHU)] and Villanúa Council economical support. MB was supported by a postdoctoral fellowship in the Juan de la Cierva Formation program provided by the Spanish Ministry of Science (ref.: FJCI-2017-31725). FG was financially supported by the “HIPATIA” research program of the University of Almería. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).