Arctic Snow Isotope Hydrology: A Comparative Snow-Water Vapor Study

The Arctic's winter water cycle is rapidly changing, with implications for snow moisture sources and transport processes. Stable isotope values (delta O-18, delta H-2, d-excess) of the Arctic snowpack have potential to provide proxy records of these processes, yet it is unclear how well the isotope values of individual snowfall events are preserved within snow profiles. Here, we present water isotope data from multiple taiga and tundra snow profiles sampled in Arctic Alaska and Finland, respectively, during winter 2018-2019. We compare the snowpack isotope stratigraphy with meteoric water isotopes (vapor and precipitation) during snowfall days, and combine our measurements with satellite observations and reanalysis data. Our analyses indicate that synoptic-scale atmospheric circulation and regional sea ice coverage are key drivers of the source, amount, and isotopic composition of Arctic snowpacks. We find that the western Arctic tundra snowpack profiles in Alaska preserved the isotope values for the most recent storm; however, post depositional processes modified the remaining isotope profiles. The overall seasonal evolution in the vapor isotope values were better preserved in taiga snow isotope profiles in the eastern Arctic, where there is significantly less wind-driven redistribution than in the open Alaskan tundra. We demonstrate the potential of the seasonal snowpack to provide a useful proxy for Arctic winter-time moisture sources and propose future analyses.

Automated summary

The study indicates that synoptic-scale atmospheric circulation and regional sea ice coverage are key drivers of the source, amount, and isotopic composition of Arctic snowpacks. Snowpack profiles in western Arctic tundra in Alaska preserved the isotope values of the most recent storm, but post-depositional processes altered the remaining isotope profiles. In taiga snowpack profiles in the eastern Arctic, the seasonal evolution of water vapor isotopes is better preserved due to less wind-driven redistribution compared to the open Alaskan tundra.