A shift towards broader and less persistent Southern Hemisphere temperature anomalies

Abstract

Temperature anomalies considerably influence the regional climate and weather of the extratropics. By the end of this century, climate models project an intensification of synoptic temperature variability in the Southern Hemisphere mid-latitudes. This intensification, however, comprises temperature anomalies with various length scales and periods, which might respond differently to anthropogenic emissions. Here, we find a shift, in coming decades, towards spatially larger and less persistent temperature anomalies in the Southern Hemisphere mid-latitudes. A shift towards larger length scales is also found during regional extreme heat events. The shift in length scale and duration is found to stem from changes in the meridional heat flux of atmospheric perturbations. Our results emphasize the importance of investigating the length scale and period-dependent changes in the mid-latitude climate, to prevent masking the different impacts of various length scales and periods, and thus provide more accurate climate projections for the mid-latitudes.