Observations of internal wave generation in the seasonally ice‐free Arctic

The Arctic is generally considered a low energy ocean. Using mooring data from the northern Chukchi Sea, we confirm that this is mainly because of sea‐ice impeding input of wind energy into the ocean. When sea‐ice is present, even strong storms do not induce significant oceanic response. However, during ice‐free seasons, local storms drive strong inertial currents (>20 cm/s) that propagate throughout the water column and significantly deepen the surface mixed layer. The large vertical shear associated with summer inertial motions suggests a dominant role for localized and seasonal vertical mixing in Arctic Ocean dynamics. Our results imply that recent extensive summer sea‐ice retreat will lead to significantly increased internal wave generation especially over the shelves and also possibly over deep waters. This internal wave activity will likely dramatically increase upper‐layer mixing in large areas of the previously quiescent Arctic, with important ramifications for ecosystems and ocean dynamics.