Countervailing regional snowfall patterns dampen Antarctic surface mass variability

Abstract. Snowfall over Antarctica, the dominant term of the Antarctic surface mass balance, displays large regional heterogeneity in temporal variability patterns. This heterogeneity has the potential to dampen variability in integrated Antarctic surface mass trends by counteracting increases in snowfall in one location with decreases in another (and vice versa). To examine the presence of countervailing regional snowfall patterns, here we present an analysis of spatial patterns of regional Antarctic snowfall variability, their broader climate drivers and their impact on integrated Antarctic snowfall variability simulated as part of a preindustrial 1800 year equilibrated Earth System Model simulation. Correlation and composite analyses based on this output allow for a statistically robust exploration of Antarctic snowfall variability. We uncover statistically significant countervailing snowfall patterns across Antarctica that are corraborated by regional modelling and ice core records. These countervailing patterns are driven by variability in large-scale atmospheric moisture transport and cause large spatial heterogeneity in temporal variability, with a dampening effect on overall Antarctic snowfall variability magnitude. This dampening has implications for regulation of Antarctic-sourced sea level variability, detection of an emergent anthropogenic signal in Antarctic mass trends and identification of AIS mass loss accelerations.