Improved Simulation of Antarctic Sea Ice by Parameterized Thickness of New Ice in a Coupled Climate Model

• Published in: Geophysical research letters Vol. 51; no. 15
• Main Authors: Fang, Yongjie, Yao, Junchen, Wu, Tongwen, Wu, Fanghua, Li, Jianglong
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16.08.2024; Wiley
• Subjects: Antarctic sea ice; Antarctic sea ice expansion; Atmosphere; BCC‐CSM2‐MR; Climate; Climate models; collection thickness; Growth rate; Ice cover; Ice formation; Ice models; Ice thickness; new ice; Ocean models; Oceans; Parameterization; Polynyas; Sea ice; Sea ice concentrations; Sea ice formation; Sea ice models; Sea ice thickness; Sea ice variations; Sea surface temperature; Simulation; Surface temperature; Surface wind; Temperature rise; Thickness; Water ice
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2024GL110166

Sea ice formation over open water exerts critical control on polar atmosphere‐ocean‐ice interactions, but is only crudely represented in sea ice models. In this study, a collection depth parameterization of new ice for flux polynya models is modified by including the sea ice concentration and ice growth rate as additional factors. We evaluated it in a climate model BCC‐CSM2‐MR and found that it improves simulation of Antarctic sea ice concentration and thickness in most of Indian and Atlantic sectors. Disagreement between the observed Antarctic sea ice expansion during 1981–2014 and the modeled decline still exists but is mitigated when the modified scheme is implemented. Further analysis indicates that these improvements are associated with the overcoming of premature closure of open water, which enhances the response of ocean to surface wind intensification during 1981–2014, and consequently slowdowns the sea surface temperature increase and the resulting Antarctic sea ice reduction. Plain Language Summary Open water ice formation critically modulates sea ice variations and the associated polar atmosphere‐ocean interaction, but is not well represented in sea ice models. In this study, a modified collection depth parameterization of new ice based on an existing scheme is presented after including sea ice concentration and ice growth rate as additional factors. We evaluated this modified scheme in BCC‐CSM2‐MR and found that it can improve the simulation of mean Antarctic sea ice thickness and concentration in winter as well as Antarctic sea ice expansion from 1981 to 2014. Further analysis implies that these improvements can be attributed to the overcoming of the premature closure of open water areas in model simulations. Key Points A modified collection thickness parameterization of new ice suitable for large‐scale climate simulations is presented It improves the simulation of Antarctic sea ice thickness and concentration, as well as Antarctic sea ice expansion during 1981–2014 The improved simulations can be attributed to the overcoming of the premature closure of open water areas where new ice forms