Deepening and eastward-shift of the Amundsen sea low lead to recent mass accumulation on the Antarctic peninsula

Following nearly two decades of mass loss, the Antarctic Peninsula has experienced mass accumulation since 2021. Using data from GRACE (Gravity Recovery and Climate Experiment), GRACE-FO (Follow On), satellite altimetry, and meteorological reanalysis, we investigate the post-2021 mass accumulation and its climatic drivers. Although mass loss resumed after 2023, the post-2021mass accumulation is unprecedented, which exhibits longer persistence and greater magnitude than previous transient mass accumulation. During 2021-2023, GRACE-FO indicated a mass gain rate of 21.5 ± 4.8 Gt /yr, attributed to enhanced precipitation. Satellite altimetry further confirms this recent mass accumulation and reveals a more detailed spatial distribution, showing a mean surface elevation increase of 23.0 ± 1.2 cm yr, predominantly occurring along the windward slopes of western Graham Land. The underlying climate mechanisms also differ from those of most previous accumulation events. The strong La Niña event deepens and shifts the Amundsen Sea Low (ASL) eastward. The strengthened ASL enhances northwesterly flow toward the Antarctic Peninsula, thereby increasing oceanic moisture transport. Meanwhile, the eastward shift of the ASL alters the moisture transport pathway, directing substantial amounts of moisture toward western Graham Land, where it ultimately resulted in enhanced precipitation. Variations in the ASL can explain approximately 68.0% of the precipitation anomalies. In addition, more frequent atmospheric rivers further contribute to precipitation increases over the Antarctic Peninsula. During 2021 to 2023, AR-induced precipitation accounted for approximately 20% of the annual total precipitation.