A Volume‐Conserved Approach to Estimating Sea‐Ice Production in Antarctic Polynyas

Abstract

AbstractAccurate estimation of sea‐ice production (SIP) is crucial to understanding the formation of Antarctic Bottom Water (AABW). Existing SIP estimates depend on the heat‐budget method, using atmospheric reanalysis together with satellite‐derived sea‐ice thickness data, and make an unrealistic assumption of no ocean heat flux occurring below the ice. Here, we propose a new method to estimate SIP based on the sea‐ice volume‐conservation (VC) theory. This new method can consider cases with sea‐ice melting (negative SIP). For a latent‐heat polynya—the Ross Sea Polynya—this method captures the synoptic SIP variations affected by warm‐water intrusions, including small‐scale melting and freezing patterns. Using the new VC approach for a sensible‐heat polynya, the Maud Rise Polynya, the sub‐sea‐ice oceanic heat flux was indirectly estimated, and the sea‐ice melting rate induced by warm water uplifted by Ekman pumping was estimated to be 0.15 and 1.44 cm d−1 for 2016 and 2017, respectively.