This work is among the first studies of Weddell Sea polynya formation in a global Earth system model (ESM) with eddy-resolving resolution in the ocean, sea ice, and atmosphere. Open ocean polynyas are regions of open water amidst the winter sea ice pack and are characterized by extreme air/sea exchange of heat and moisture. Their occurrence in nature, as well as their representation in ESMs, is very variable and episodic, potentially giving rise to significant model biases. Understanding the processes that precondition the Weddell Sea for the formation of polynyas, as well as the processes that trigger polynya formation, is critical for quantifying and reducing these biases. This study shows that an accurate representation of small-scale bathymetry, in particular, a seamount called the Maud Rise, is essential for generating Maud Rise polynyas.
This study emphasizes the impact that small-scale features can have on large-scale climate processes. It shows that low-resolution ocean models cannot represent processes that are essential for the formation of open-ocean polynyas, and hence ignore an important mode of air/sea heat exchange and Antarctic Bottom Water formation.
This study shows that resolving small-scale bathymetry and its non-linear interaction with the circulation is critical for faithfully representing polynyas in the Weddell Sea. This explains the general absence of polynyas in low-resolution ESMs.