The Phenology of Arctic Ocean Surface Warming

In this work, we explore the seasonal relationships (i.e., the phenology) of sea ice retreat, ocean surface warming, and atmospheric heat fluxes in the Pacific Sector of the Arctic Ocean, using satellite and reanalysis data.  We find that early ice retreat leads to warmer summertime ocean surface temperatures over the continental shelves and southern basins.  This relationship is weaker in the Chukchi Sea (where ocean advection plays a large role) and in far northern latitudes (where atmospheric heat fluxes are weak).  This result helps to explain the very different ocean warming responses found in two recent years with extreme ice retreat, 2007 and 2012.  We also find that the timing of ice retreat impacts the date of maximum ocean surface warming, owing to a change in the ocean surface buoyancy and momentum forcing that occurs in early August that we term the Late Summer Transition.  Our results indicate that in the near-term, earlier ice retreat is likely to cause enhanced ocean surface warming in much of the Arctic Ocean, although not in far northern areas, where earlier retreat for now still creates open water at a time of weak atmospheric heat fluxes.