Modelling sea ice formation in the Terra Nova Bay polynya

• Published in: Journal of Marine Systems
• Main Authors: Sansiviero, M., Morales Maqueda, M. Ã., Fusco, G., Aulicino, G., Flocco, D., Budillon, G.
• Other Authors: Morales Maqueda, M. Ã .
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Coupled model; Katabatic wind; Polynya; Sea ice; Oceanography; Ecology; Evolution; Behavior and Systematic; Aquatic Science; Antarctic; Ross Sea; Terra Nova Bay; Drygalski; Drygalski Ice Tongue; Antarc*
• Online Access: http://hdl.handle.net/11566/265365; https://doi.org/10.1016/j.jmarsys.2016.06.013

Antarctic sea ice is constantly exported from the shore by strong near surface winds that open leads and large polynyas in the pack ice. The latter, known as wind-driven polynyas, are responsible for significant water mass modification due to the high salt flux into the ocean associated with enhanced ice growth. In this article, we focus on the wind-driven Terra Nova Bay (TNB) polynya, in the western Ross Sea. Brine rejected during sea ice formation processes that occur in the TNB polynya densifies the water column leading to the formation of the most characteristic water mass of the Ross Sea, the High Salinity Shelf Water (HSSW). This water mass, in turn, takes part in the formation of Antarctic Bottom Water (AABW), the densest water mass of the world ocean, which plays a major role in the global meridional overturning circulation, thus affecting the global climate system. A simple coupled sea ice–ocean model has been developed to simulate the seasonal cycle of sea ice formation and exportwithin a polynya. The sea icemodel accounts for both thermal andmechanical ice processes. The oceanic circulation is described by a one-and-a-half layer, reduced gravity model. The domain resolution is 1 km× 1 km, which is sufficient to represent the salient features of the coastline geometry, notably the Drygalski Ice Tongue. The model is forced by a combination of Era Interim reanalysis and in-situ data from automatic weather stations, and also by a climatological oceanic dataset developed fromin situ hydrographic observations. The sensitivity of the polynya to the atmospheric forcing is well reproduced by the model when atmospheric in situ measurements are combined with reanalysis data. Merging the two datasets allows us to capture in detail the strength and the spatial distribution of the katabatic winds that often drive the opening of the polynya. The model resolves fairly accurately the sea ice drift and sea ice production rates in the TNB polynya, leading to realistic polynya extent estimates. The model-derived polynya ...