Can current reanalyses accurately portray changes in Southern Annular Mode structure prior to 1979?

Abstract Early reanalyses are less than optimal for investigating the regional effects of ozone depletion on Southern Hemisphere (SH) high-latitude climate because availability satellite sounder data from 1979 significantly improved their accuracy in sparse regions, leading to a coincident inhomogeneity. To determine whether current better at SH high-latitudes pre-satellite era, here we examine capabilities European Centre Medium-range Weather Forecasts (ECMWF) fifth generation reanalysis (ERA5), Twentieth Century Reanalysis version 3 (20CRv3), and Japanese Meteorological Agency (JMA) 55-year (JRA-55) reproduce help explain pronounced change relationship between Annular Mode (SAM) Antarctic near-surface air temperatures (SAT) 1950 (EARLY period) 1980–2020 (LATE period). We find that ERA5 best reproduces SAT EARLY period is also most homogeneous across LATE periods. 20CRv3 provide good representation SAM both periods with JRA-55 only similarly skilful period. Nevertheless, all three show marked SAM-SAT relationships two In particular, demonstrate observed switch sign Peninsula: analysis changes structure associated meridional wind anomalies reveal these positive linked cold southerly winds during warm northerly period, thus providing simple explanation reversal.