Atmospheric Wind Biases: A Challenge for Simulating the Arctic Ocean in Coupled Models?

Many state-of-the-art climate models do not simulate the Atlantic Water (AW) layer in Arctic Ocean realistically enough to address question of future Atlantification and its associated feedback. Biases concerning AW are commonly related insufficient resolution excessive mixing ocean component as well unrealistic Atlantic-Arctic exchange. Based on sensitivity experiments with FESOM1.4, ocean–sea-ice global model AWI-CM1, we show that even if all impediments for simulating addressed model, new biases develop after coupling an atmosphere model. By replacing wind forcing over winds from a coupled simulation common bias atmospheric sea level pressure (SLP) gradient lead differences surface stress Ekman transport. Fresh water gets redistributed leading changes halosteric height distribution. Those strengthening anticyclonic circulation Canadian Basin, so deep counterflow carrying warm reversed Basin develops. The SLP Nordic Seas weaken cyclonic reduced transport into through Fram Strait but increased Barents Sea Opening. These effects together cold Eurasian Basin. An underestimation ice concentration can significantly amplify induced biases.