海冰模式CICE4.0与LASG/IAP气候系统模式的耦合试验

利用美国Los Alamos国家实验室发展的最新海冰模式(CICE4.0)替代了LASG/IAP气候系统模式(FGOALS_g1.1)中的海冰模式(CSIM4), 形成新的耦合模式。在此基础上, 利用新的耦合模式对20世纪中后期的全球气候进行了模拟, 来检验CICE4.0对耦合模式中海冰和海洋模拟结果的改进。结果表明CICE4.0对于FGOALS_g1.1的极地气候模拟有一定改进作用, 主要表现在:(1) 南北极海冰边缘碎冰区显著减少; (2) 南大洋海表温度和海冰的模拟明显改善, 分布特征与观测非常吻合。但是新耦合模式也存在如下不足: (1) 北大西洋海冰相对偏多, 北大西洋经圈翻转环流大大减弱, 这主要是由于北大西洋海表面温度的冷误差造成的; (2) 南北极大气环流场的模拟无明显改善。此外, 本文还比较了采用不同短波辐射方案对于耦合模拟结果的影响, 结果表明, 相对于CCSM3短波辐射方案, Delta-Eddington方案模拟的海表面温度偏冷, 海冰厚度偏厚, 北大西洋经圈翻转环流略有偏弱。

Experiment of Coupling Sea Ice Model CICE4.0 to LASG/IAP Climate System Model

The latest Los Alamos sea ice model (CICE4.0) is used to replace the sea ice model (CSIM4) in the LASG/IAP climate system model (FGOALS_g1.1), and the new coupled model has been integrated for the second half of the 20th century with observed forcings. Compared with FGOALS_g1.1, CICE4.0 improves polar climate simulations in the following aspects: 1) The area with small ice concentration near the ice edge is reduced remarkably. 2) Spatial distributions of both sea ice and sea surface temperature in the Southern Ocean resemble observations. However, there are some problems, including excessive sea ice in the North Atlantic and weakening of the North Atlantic meridional overturning relative to FGOALS_g1.1, which are largely due to large cold bias of sea surface temperature in the North Atlantic. As to atmospheric circulation, there is no significant improvements compared with FGOALS_g1.1. In addition, impacts of different shortwave radiation schemes, including CCSM3 and Delta-Eddington, on sea ice simulations in the new coupled model are discussed. The results show that the Delta-Eddington scheme results in thicker sea ice, colder sea surface temperature, and weaker North Atlantic meridional overturning as compared to the CCSM3 scheme.