CICE海冰模式中反照率相关参数对北极海冰模拟的影响

国家气候中心气候系统模式BCC_CSM2.0最新耦合了美国Los Alamos国家实验室发展的海冰模式CICE5.0，为试验模式中与反照率相关参数的敏感性及其对模拟结果的影响，提高模式对北极海冰的模拟能力，选取海冰模式中3个主要参数进行了敏感性试验。利用以BCC_CSM2.0耦合框架为基础建立的海冰-海洋耦合模式，选取CORE资料为大气强迫场开展试验，试验的3个参数分别为冰/雪表面反射率、雪粒半径和雪粒半径参考温度。结果表明，参数取值的不同对北极海冰的模拟有显著的影响，优化后的取值组合极大提高了模式的模拟能力，主要表现在:（1）改善了对北极冬季海冰厚度的模拟，海冰厚度增大，与观测资料更为吻合；（2）显著提高了对北极夏季海冰密集度的模拟能力，从而模拟的北极海冰范围年际循环与观测更为一致。参数取值的优化改进了模式对海冰反照率的模拟，进而影响了冰面短波辐射的吸收和海冰表层的融化，最终提高了模式对海冰密集度和厚度的模拟效果。 

Influence of albedo related parameters on the simulation of Arctic sea ice by CICE

The Los Alamos sea ice model CICE5.0 has been coupled to Beijing Climate Center Climate System Model (BCC_CSM2.0). To evaluate the effects of parameter optimization and improve the model performance on Arctic sea ice simulation, three parameters, including the emissivity, the maximum melting snow grain radius and the reference temperature of snow grain radius, are selected for sensitivity analysis. All numerical experiments are carried out with the ice-ocean model based on the BCC_CSM2.0 while the atmospheric circulation model is replaced by data model and forcing data are from Coordinated Ocean-ice Reference Experiments (CORE) data set. Results show that the model performance on Arctic sea ice simulation has been satisfactorily improved after the three parameters are tuned. (1) The sea ice thickness increases remarkably not only in the winter but also in the summer and is more comparable with observations. (2) The spatial distribution of summer ice concentration resembles observations better and the simulated sea ice extent significantly improves. Analysis of sea ice mass budget reveals that parameter optimization has enhanced the physics of albedo, which in turn affects the absorption of solar radiation and finally improves the model capability for simulations of sea ice concentration and thickness. However, some problems still remain especially in the simulation of sea ice area in the winter.