Relationship between synoptic forcing and polynya formation in the Cosmonaut Sea: 2. Regional climate model simulations

Abstract

In part I of this series [Arbetter et al., 2004], a relationship was found in the observations between synoptic atmospheric systems and polynya formation in the Cosmonaut Sea region of Antarctica. In this study, we use a regional coupled atmosphere‐sea ice model to investigate the role of atmospheric forcing of the polynyas in this area. The model successfully simulates both latent and sensible heat polynyas which are found in the region. In particular, a deep‐ocean polynya is formed coincident with the passage of an atmospheric synoptic scale system. The divergence in the sea ice is found to be highly correlated with the atmospheric divergence. We conclude that the initial formation of a polynya can be caused by the interaction of the atmospheric synoptic scale and the continental katabatic wind regimes. While we cannot directly evaluate the role of the ocean using the present model simulations, we performed experiments with different levels of prescribed basal heat flux. These experiments highlight a polynya which could be initiated by the winds and maintained by the oceanic heat. This leads to the concept of a wind‐driven sensible heat polynya, not typical of other deep‐ocean polynyas such as the Weddell polynya of the 1970s.