J. Geophys. Res. Atmos. http://doi.org/bksf (2016)

Credit: WOLFGANG KAEHLER / CONTRIBUTOR / LIGHTROCKET / GETTY

Sea ice is decreasing in the Arctic but year-to-year variability in sea ice extent is large. Ice extent is influenced by atmospheric circulation, with temperatures dictating ice melt, and winds shifting the ice. To investigate the link between atmospheric circulation patterns and regional sea ice changes, Amanda Lynch of Brown University, Rhode Island, USA and colleagues use a self-organizing map framework. They use satellite data of daily sea ice extent to calculate monthly mean open water areas, and reanalysis sea level pressure data to compare the Pacific and Atlantic sectors.

They find that the September open water fraction is increasing more rapidly in the Pacific than the Atlantic sector, with the Pacific also experiencing greater variability, which they attribute to consistent ice export in the Atlantic sector. In years with greater sea ice loss, and therefore a larger open water fraction, the mechanism is the same for both sectors, with warmer temperatures melting ice and southerly winds driving the remaining ice towards the pole. However, in years with more ice and less open water, the authors' find two different mechanisms at play — cooler temperatures or transport of ice to the south, the latter of which would reduce ice thickness.