Role of precipitation and extreme precipitation events on the variability of ice core surface mass balances in Dronning Maud Land: insights from RACMO2.3 and statistical downscaling

Abstract

The Antarctic Ice Sheet (AIS) is the most uncertain contributor to future sea level rise for projections by the end of this century. One of the main drivers of future AIS mass changes is the surface mass balance (SMB) of the ice sheet, which is associated with a number of uncertainties, including its large temporal and spatial variability. The SMB is influenced by a complex interplay of the various processes driving it, including large-scale atmospheric circulation, ice sheet topography, and other interactions between the atmosphere and the snow/ice surface. This spatial and temporal variability is identified in three ice cores located at the crests of adjacent ice rises in coastal Dronning Maud Land, each approximately 90 km apart, which show very contrasting SMB records. In this study, we analyze the role of precipitation and extreme precipitation events (EPEs) in this variability. Our results, based on the RACMO2.3 model and a dataset derived from statistical downscaling, confirm that precipitation is the primary driver of SMB, and that synoptic-scale EPEs play a significant role in controlling interannual variability in precipitation and thus SMB. Shedding light on the intricate nature of SMB variability, our results also demonstrate that precipitation and EPEs alone cannot explain the observed contrasts in SMB records among the three ice core sites and suggest that other processes may be at play. This underscores the importance of adopting comprehensive, interdisciplinary methods, like data assimilation that combines observations and the physics of models, to unravel the underlying mechanisms driving this variability.