APEX: The Arctic Polynya Experiment

Abstract

A field experiment has been initiated to address the mesoscale oceanographic, sea ice, and meteorological processes associated with a polynya, or high‐latitude area of semipermanent open water and vigorous new ice growth. This experiment, called the Arctic Polynya Experiment (APEX), is taking place in and around the St. Lawrence Island Polynya on the northern Bering Sea shelf. This polynya was selected for study because it typifies many such features found throughout the Arctic and Antarctic, is relatively accessible, and lies in a region that is of considerable interest due to projected resource development.A polynya is an open water area which persists despite environmental conditions which would seem to dictate formation of an ice cover. Such areas may be due to a variety of causes. The majority appear to occur, however, when a physical barrier, such as a coastline or a channel constriction, allows prevailing winds or currents to sweep newly formed ice away while at the same time preventing existing ice from moving into the area. The St. Lawrence Island Polynya occurs along the southern, or lee, coastline of St. Lawrence Island as the prevailing northerly winds sweep ice away toward the south. Polynyas are of oceanographic interest because they are sites for vigorous, continuous ice formation and are therefore sources both of new ice and of dense, brine‐enriched water. They are of interest meteorologically because the associated strong sea‐air heat fluxes modify the atmospheric boundary layer.