Correlation of the seasonal isotopic amplitude of precipitation with annual evaporation and altitude in alpine regions

Abstract The time series of stable water isotope composition relative to IAEA-GNIP meteorological stations located in alpine zones are analyzed in order to study how the amplitude of the seasonal isotopic composition of precipitation (Aδ) varies along a vertical transect. A clear relationship between Aδ and local evaporation is obtained, with slopes of â 0.87 â °/100 mm/yr and â 7.3 â °/100 mm/yr for Aδ18O and Aδ2H, respectively. When all sampling points of the vertical transect receive the same moisture sources, then a linear relationship between Aδ and elevation is obtained, with vertical gradients of 0.16 â °/100 mm/yr and 1.46 â °/100 mm/yr for Aδ18O and Aδ2H, respectively.