Spatial and temporal variability of snow isotopic composition on Mt. Zugspitze, Bavarian Alps, Germany

High amounts of precipitation are temporarily stored in high-alpine snow covers and play an important role for the hydrological balance. Stable isotopes of hydrogen (delta H-2) and oxygen (delta O-18) in water samples have been proven to be useful for tracing transport processes in snow and meltwater since their isotopic ratio alters due to fractionation. In 18 snow profiles of two snowfall seasons, the temporal and spatial variation of isotopic composition was analysed on Mt. Zugspitze. The delta O-18 and delta H-2 ranged between -26.7 parts per thousand to -9.3 parts per thousand and -193.4 parts per thousand to -62.5 parts per thousand in 2014/2015 and between -26.5 parts per thousand to -10.5 parts per thousand and -205.0 parts per thousand to -68.0 in 2015/2016, respectively. Depth-integrated samples of entire 10 cm layers and point measurements in the same layers showed comparable isotopic compositions. Isotopic composition of the snowpack at the same sampling time in spatially distributed snow profiles was isotopically more similar than that analysed at the same place at different times. Melting and refreezing were clearly identified as processes causing isotope fractionation in surficial, initial base or refrozen snow layers. For the future, a higher sampling frequency with detailed isotopic composition measurements during melt periods are recommended to improve the understanding of mass transport associated with snowmelt.