Daily precipitation variability in Antarctica causally dominated by large-scale atmospheric dynamics
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Antarctica's climate system is undergoing rapid changes, but causal links between its components, such as sea ice, precipitation, and atmospheric dynamics remain poorly understood. While recent studies suggest that declining sea ice may enhance Antarctic surface mass balance (SMB) through increased moisture availability for precipitation, these findings are mainly based on correlational evidence, and the underlying causal mechanisms are still debated. In this study, we combine correlation analysis with the PCMCI+ causal discovery algorithm, applied to reanalysis data, to study the relationships between sea ice concentration, evaporation, moisture convergence, and precipitation over Antarctica. Our results show that meridional wind variability and moisture convergence are the primary drivers of daily precipitation variability across the continent. Unlike some previous studies focusing on longer timescales (e.g. monthly or interannual), we do not find a direct causal influence of sea ice concentration on precipitation. Instead, large-scale atmospheric dynamics dominate day-to-day variability, mediating the connection between sea ice and precipitation. While longer-term feedbacks such as ice-albedo effects may still be relevant, our findings emphasise the critical role of synoptic-scale atmospheric processes in controlling Antarctic precipitation. These results have important implications for a better understanding of processes influencing the Antarctic mass balance, particularly in the context of ongoing and future global sea level rise.
