The changing mass of the Antarctic Ice Sheet during ENSO-dominated periods in the GRACE era (2002–2022)

Abstract. Large-scale modes of climate variability significantly influence Antarctic Ice Sheet (AIS) mass change. Improved understanding of the relationship between these climate modes and AIS mass change can help reduce uncertainties in future ice mass estimates and its contribution to sea level rise. However, the spatiotemporal patterns of AIS mass variation driven by El Niño Southern Oscillation (ENSO)-induced atmospheric circulation remain unclear. Here, we investigate AIS variability during different ENSO periods using Gravity Recovery and Climate Experiment (GRACE) observed mass changes over the period 2002 to 2022. The results show strong event-to-event spatial variability in how the ENSO teleconnection manifests over the AIS. These differing spatial patterns are primarily driven by changes in the Amundsen Sea Low (ASL) strength, location, and extent, which alter circulation patterns and moisture flow in West Antarctica. In East Antarctica, ice mass variability is largely influenced by the positioning of cyclonic and anticyclonic anomalies, primarily driven by the Southern Annular Mode (SAM); however, ENSO signals are also present. In both East and West Antarctica, this study shows that the spatial impact of any given ENSO event, as derived using standard tropical atmospheric metrics (Sea Surface Temperature (SST) and pressure anomalies), and its influence on the ASL and Southern Ocean circulation can be equally (and in some cases more) important to AIS variability. GRACE provides an opportunity to understand event-scale ENSO precipitation independently of numerical models.