Early Winter Triggering of the Maud Rise Polynya

What triggers Maud Rise polynya, a large opening in the winter Antarctic sea ice, is still debated. We show that upcoming of all polynyas can be detected early up to four months ahead, especially since 2002 expansion satellite observations. In polynya years, continuous anomalous ice thinning begins May, caused by atmospheric and oceanic forcings. Dynamically, an cyclonic circulation atmosphere ocean strengthens Weddell Gyre exerts anomalously intense stresses on ice. Thermodynamically, warm water advected intensified circulation, most importantly entrained into mixed layer, thins from below at beginning freezing season, preconditioning region for event later. This four-month-ahead pattern enables predictions improved expedition planning sensor deployment.