CICE5.0与BCC_CSM2.0模式的耦合及对北极海冰的模拟评估

本文将美国Los Alamos国家实验室发展的最新海冰模式CICE5.0引入国家气候中心气候系统模式BCC_CSM2.0,替代原有的海冰模式SIS,形成一个新的耦合模式。在此基础上,评估新耦合模式对1985-2009年北极海冰的模拟性能,检验引入CICE5.0后对耦合模式中北极海冰、海洋和大气模拟结果的改进。结果表明,引入CICE5.0后,模式能较好地模拟出北极海冰的空间分布、季节以及年际变化特征。相比于旧版本耦合模式,新耦合模式模拟的北极多年冰增多、一年冰减少,同时,海冰增厚、海冰流速减慢,模拟效果得到显著改进,对波弗特涡流模拟的改善尤为明显。进一步分析发现,相比于SIS,CICE5.0对北极海冰特别是海冰厚度模拟性能的提升,在耦合进入BCC_CSM2.0后,会触发冰-温的正反馈机制,改进了模式对海平面气压场、表层气温和海表温度的模拟,由此进一步提高了模式对北极海冰的模拟能力。

Couping of CICE5.0 with BCC_CSM2.0 model and its performance evaluation on Arctic sea ice simulation

The latest Los Alamos sea ice model (CICE5.0) is coupled to the Beijing Climate Center coupled system model (BCC_CSM2.0) by replacing its original sea ice model (SIS). The performance of the new coupled model in simulating silent features of Arctic sea ice during 1985-2009 is thoroughly assessed through a comparison to both the original version and observations. The results show that the new coupled model can reasonably capture the spatial pattern, seasonal and inter-annual variation of Arctic sea ice. The CICE5.0 significantly improves the Arctic sea ice simulation, which includes a decrease (increase) of one year (multi-year) sea ice area, an increase in ice thickness, a reduction in ice motion, and a more realistic Beaufort Gyre. Further analysis indicates that, compared with the SIS, the better performance of the CICE5.0 in simulating the Arctic sea ice, especially for its thickness, results in positive ice-temperature feedbacks when coupled with the BCC_CSM2.0. As a result, the surface air temperature, sea level pressure, and the sea surface temperature are better simulated, which further improves the Arctic sea ice simulation.