Abstract
The Arctic’s winter water cycle is rapidly changing, with implications for snow moisture sources and transport processes. Stable isotope values (δ18O, δ2H, 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.
Highlights
Since the mid-1990s, Arctic surface air temperatures (SATs) have warmed at twice the global mean rate [1]
Pallas mean air temperature was −7.7 ◦C and had fewer extreme variations, with values ranging from 3.0 ◦C to −26.0 ◦C, with the temperature minima occurring on 5 February 2019
Our analyses indicate that both the total amount of snow and isotope values in Arctic snowpacks are influenced by synoptic-scale atmospheric circulation
Summary
Since the mid-1990s, Arctic surface air temperatures (SATs) have warmed at twice the global mean rate [1] This amplification of the Arctic is driving pronounced changes in the hydrological cycle, including shifting ocean and atmospheric circulation, altered precipitation and humidity patterns, large-scale permafrost degradation, and precipitous ice-mass loss from glacierized regions throughout the Arctic [2,3,4,5]. The rapid loss of sea ice [6] has been linked to shifting atmospheric moisture source and transport regimes across the Arctic, with implications for the meridional transport of moisture between mid- and high-latitudes [7,8,9] These impacts are evident, for example, during atmospheric river events, where plumes of warm water vapor are rapidly transported into the Arctic [10,11], and the advection of moisture from the Arctic to lower latitudes, such as during cold air outbreaks and transient cyclones [12,13]. Understanding current Arctic water cycle changes, the shifting moisture sources of snow and the fate and function of snowmelt, is imperative
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