Seasonal Antarctic pressure variability during the twentieth century from spatially complete reconstructions and CAM5 simulations

To address this issue, the non-summer multi-decadal variability in pressure reconstructions poleward of 60 degrees S is evaluated and assessed in conjunction with climate model simulations throughout the twentieth and early twenty-first centuries to understand historical atmospheric circulation variability over Antarctica.

Austral autumn and winter seasons show broadly similar patterns, with negative anomalies in the early twentieth century (1905-1934), positive pressure anomalies in the middle twentieth century (1950-1980), and negative pressure anomalies in the most recent period (1984-2013), consistent with concurrent trends in the SAM index. In autumn, the anomalies are significant in the context of estimates of interannual variability and reconstruction uncertainty across most of the Antarctic continent, and the reconstructed patterns agree best with model-generated patterns when the simulation includes the forced response to tropical sea surface temperatures and external radiative forcing.