Time series analysis of sea ice production in polynyas in Amery ice shelf region of Antarctica

Antarctic coastal polynyas are important sea ice production regions and the process of sea ice production is accompanied by the formation dense water, which further affects the global circulation of ocean currents. Therefore, it is important to study the ice production of the Antarctic coastal polynyas. The study area of this paper is the Amery Ice Shelf region along the Antarctic coast because polynyas in Amery Ice Shelf region are major source areas of sea ice production in Antarctica. What’s more, there was a collapse event occurred on the Amery Ice Shelf from September 20 to 25 in 2019. The study period is 2013-2020 during winter time (from March to October). In this study, the thin ice thickness is retrieved based on AMSR2 monthly brightness temperatures (TBs) data by applying empirical formulas, and then two polynyas (Cape Darnley Polynya and Mackenzie Bay Polynya) are extracted in the Amery Ice Shelf region based on thin ice thickness. It is found that the area of the two polynyas fluctuates greatly, with maximal area frequently occurring in March. Then, sea ice production of the two polynyas is calculated in conjunction with ERA5 reanalysis meteorological data. The annual and intra-annual analyses of sea ice production in this study reveals that the inter-annual sea ice production of the two polynyas fluctuated considerably and reached a maximum in 2018, while the maximum intra-annual sea ice production of the two polynyas frequently occurred in March or April. As for the collapse event occurred on the Amery Ice Shelf in 2019, daily sea ice production of the two polynyas for a total of 40 days before and after the collapse event is calculated. Based on the result, it is assumed that the collapse event may have exacerbated the volatility and instability of sea ice production.