An overview of Antarctic polynyas: sea ice production, forcing mechanisms, temporal variability and water mass formation
at : Sep 10, 2021 17:21:57  (view:867)

An overview of Antarctic polynyas: sea ice production, forcing mechanisms, temporal variability and water mass formation

Zheng Wei1, Zhaoru Zhang1,*, Timo Vihma2, Xiaoqiao Wang1, Yuanjie Chen1

1 School of Oceanography, Shanghai Jiao Tong University, Shanghai, China;

2 Meteorological Research, Finnish Meteorological Institute, Helsinki, Finland

Abstract Polynyas are irregular open water bodies within the sea ice cover in polar regions under freezing weather conditions. We review the progress of research work on dynamical forcing, sea ice production (SIP), and water mass formation for both latent and sensible heat polynyas in the Southern Ocean, as well as the variability and controlling mechanisms of polynya processes on different time scales. Polynyas play an irreplaceable role in the regulation of global ocean circulation and biological processes in regional ocean ecosystem. Around Antarctica, there are 13 major coastal polynyas, which are mainly located on the western side of the coastline protruding the ocean. During the formation of coastal polynyas in seven regions mainly in East Antarctica, brine rejection triggered by high SIP due to offshore wind forcing, tidal or other ocean currents results in formation of high salinity shelf water, which is the predecessor of the Antarctic bottom water — the lower limb of the global thermohaline circulation. In the Indian sector of the Southern Ocean, there are two types of persistent open-ocean polynyas formed by combination of convection processes in the ocean and a negative wind stress curl. Convection processes in Maud Rise Polynya and Weddell Polynya bring nutrients into the upper ocean, support biological activities, and make the polynya regions an important sink for atmospheric carbon dioxide. The limitations and challenges in polynya research are also discussed.

Keywords Antarctic polynyas, forcing mechanisms, sea ice production, water mass formation, temporal variability