Impacts of Tropopause Polar Cyclones on Arctic Sea Ice Loss

Arctic sea ice exhibits considerable and potentially abrupt year to year variability, with changes amplified as the ice thins. Extremes of summer Arctic sea ice loss are intimately connected to the atmospheric forcing. On sub-seasonal to seasonal time scales, there are significant correlations between upper level heights, sea level pressure, and sea ice loss. Individual synoptic cyclones can also drive significant ice loss.Cyclonic tropopause polar vortices (TPVs) are common, coherent upper level potential vorticity anomalies with typical radii of 100 to 1000 km and lifetimes of days to months. Here, we test the hypothesis that TPVs have significant impacts on the evolution and predictability of summer sea ice loss.Historical TPV-based composites reveal coherent mass, momentum, and energy sea ice forcings under TPVs, with implications for pack ice maintenance and marginal ice loss. Coupled MPAS-CESM sensitivity experiments with strengthened and weakened TPVs quantify the sea ice response to these forcings at both short- and extended-range time scales. The coupling of forcings between TPVs and larger scales is seen to contribute to the significance of impacts. Since modelling systems exhibit systematic errors in the representation of TPVs, resolving these errors may realize the potential predictability associated with TPVs.