Rapid widening of Arctic marginal ice zone over satellite record

Dense pack ice transitions to open ocean over a region of broken ice termed the marginal ice zone (MIZ) -- a highly dynamic region where ice cover lies close to an open ocean boundary and intense atmosphere-ice-ocean interactions take place. The warm-season Arctic MIZ has reduced in area and trended poleward consistent with reductions in sea ice extent over the satellite era (1979-present), while the width of the warm-season Arctic MIZ has increased by nearly 30% over the same time period. We show that the marked widening trend is linked to changes in atmospheric circulation and polar heat content that are rendering the sea ice younger and thinner at the beginning of the melt season. Discovery of the warm-season width trend was enabled by the Laplacian-based MIZ analysis method we developed and recently published in a study of cold-season MIZ. Our figure shows an example of the analysis method for 15 August 1983 (the solution to Laplace's equation is shown by color shading with gray contours, and examples of the width measurements following the gradient of the solution are shown by black curves).