The linearity of the El Nino teleconnection to the Amundsen Sea region

El Nino Southern Oscillation (ENSO) drives interannual variability in West Antarctic climate through altering atmospheric circulation in the Amundsen Sea region (ASR). The El Nino-ASR teleconnection is known to be strongest in austral winter and spring, but its variation with El Nino amplitude is underexplored. This study uses experiments from the HadGEM3-A climate model to investigate the El Nino-ASR teleconnection for a range of imposed SST perturbations spanning weak (0.75 K) to strong (3 K) amplitudes. In austral winter, the El Nino-ASR teleconnection behaves linearly for El Nino amplitudes up to 2.25 K, but is found to weaken for stronger forcing (3 K). The anomalous Rossby wave source in the subtropical South Pacific increases monotonically with El Nino amplitude. However, a Rossby wave reflection surface originally located in the western South Pacific sector extends progressively eastward with increasing El Nino amplitude, reducing wave propagation into the ASR. The wave reflection surface is associated with curvature in the upper tropospheric zonal winds which intensifies as the subtropical jet strengthens under El Nino forcing. In contrast, the El Nino-ASR teleconnection in austral summer, which more closely resembles the Southern Annular Mode, is found to increase linearly for El Nino amplitudes up to 3 K. The results explicitly demonstrate that a linear approximation of the El Nino teleconnection to the ASR is reasonable based on the range of El Nino amplitudes observed in recent history.