Abstract
Over the last century, the increase in snow accumulation has partly mitigated the total dynamic Antarctic Ice Sheet mass loss. However, the mechanisms behind this increase are poorly understood. Here we analyze the Antarctic Ice Sheet atmospheric moisture budget based on climate reanalysis and model simulations to reveal that the interannual variability of regional snow accumulation is controlled by both the large-scale atmospheric circulation and short-lived synoptic-scale events (i.e. storm systems). Yet, when considering the entire continent at the multi-decadal scale, only the synoptic-scale events can explain the recent and expected future snow accumulation increase. In a warmer climate induced by climate change, these synoptic-scale events transport air that can contain more humidity due to the increasing temperatures leading to more precipitation on the continent. Our findings highlight that the multi-decadal and interannual snow accumulation variability is governed by different processes, and that we thus cannot rely directly on the mechanisms driving interannual variations to predict long-term changes in snow accumulation in the future.
Highlights
IntroductionThe increase in snow accumulation has partly mitigated the total dynamic Antarctic Ice Sheet mass loss
Over the last century, the increase in snow accumulation has partly mitigated the total dynamic Antarctic Ice Sheet mass loss
While the synoptic-scale transport positively contributes to the mean snow accumulation for each of the seven regions, the contribution of the large-scale transport is only positive for the Antarctic Peninsula and the West Antarctic Ice Sheet (WAIS) (18 ± 9% and 32 ± 6%, respectively)
Summary
The increase in snow accumulation has partly mitigated the total dynamic Antarctic Ice Sheet mass loss. We analyze the Antarctic Ice Sheet atmospheric moisture budget based on climate reanalysis and model simulations to reveal that the interannual variability of regional snow accumulation is controlled by both the large-scale atmospheric circulation and short-lived synoptic-scale events (i.e. storm systems). Opposing this mass loss, snowfall has increased over much of the AIS since the early 19th century, as shown in a recent AIS-wide reconstruction based on ice core compilation[4] This positive trend in snow accumulation, i.e. the difference between total precipitation and losses from the evaporation/sublimation, wind snow redistribution, and meltwater runoff, is estimated to have led to the mitigation of sea-level rise[4]. The goal is to investigate all the known mechanisms that explain the snow accumulation variability from the interannual to multi-decadal scale, at both regional and continental scales, in a common framework
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