Future Atmospheric Rivers in Antarctica: Characteristics and Impacts With the IPSL Model

Abstract Atmospheric rivers (ARs) are narrow corridors of intense water vapor transport that have significant impacts on the Antarctic surface mass balance (SMB) through both snow accumulation and surface melt due to rain and heat. To estimate their impacts on future SMB, we study Antarctic ARs in an ensemble of 21st‐century simulations of the IPSL‐CM6 model. Although the number of detected ARs continuously increases when using a constant detection threshold based on recent moisture fluxes, it remains stable with an adaptive threshold evolving with the rising background moisture. In addition, ARs penetrate further into Antarctica following a wave‐number 3 pattern. The severity of Antarctic ARs, measured by moisture fluxes, is projected to increase following the moisture content given by the Clausius‐Clapeyron relation. The corresponding SMB impacts all become larger with both increasing snowfall and coastal surface melt and rainfall. However, their overall influence on the SMB is dominated by the increased snow accumulation related to ARs, which is rising by 17% at the scale of the continent. This is much larger than the overall increase in snow accumulation from all events combined, which is 9%, and is more closely related to the rise in total humidity in relation with temperature—that is, linked to the Clausius‐Clapeyron relation.