Surface snow isotopic composition: Post-depositional processes in an alpine snowpack

Stable water isotopes are natural tracers allowing to reconstruct the history of a water parcel. They are used as climate proxies and to better understand the hydrological cycle. The snow isotopic composition is directly influenced by temperatures and atmospheric conditions during water evaporation, vapor transport, and snowfall formation. The isotopic signal is often assumed to be preserved in the snowpack. However, multiple post-depositional processes such as drifting and blowing snow, isotopic fractionation during snow sublimation, vapor deposition, and melt influence the snow isotopic composition. To better understand the variation of the snow isotopic signal, snow samples have been collected on the Weissfluhjoch in the Swiss Alps during multiple field campaigns between 2017 and 2022. The results show a clear diurnal cycle during periods with important latent heat exchange (positive and negative). Periods of sublimation correspond to an enrichment of the snow surface and melting events cause a significant shift in the signal of the entire snowpack.