CICE海冰模式中融池参数化方案的比较研究

Comparison of melt pond parameterization schemes in CICE model

冰面融池的反照率介于海水和海冰之间,获得较准确的融池覆盖率对认识极区气冰海耦合系统的热量收支有重要意义。在数值模式中,融池覆盖率的模拟结果直接影响到冰面反照率计算的准确性,本文对CICE5.0中的3种融池参数化方案进行了较系统的比较分析,结果显示3种方案各有优缺点,模拟结果都存在一些问题。cesm方案中判断融池冻结的条件更为合理。比较而言,融池冻结条件更改后的topo方案模拟的北冰洋区域平均融池覆盖率的年际变化幅度、融池覆盖范围、融池发展盛期持续时间与MODIS数据最接近。通过修改CICE5.0中的代码漏洞,研究了融池水的垂向渗透效应,这一效应会带来一些负面影响,如lvl方案中多年冰上几乎没有融池,说明目前的CICE模式中对于海冰渗透性演化或其他物理机制的处理仍有待改进。最后,着重讨论了topo方案的改进思路。

The albedo of melt ponds is greater than open water but less than bare sea ice. It＇s important to obtain ac curate melt pond fraction information for the study of heat budget in the atmosphere-ice-ocean system. In numerical model, melt pond fractions impact the calculation of sea ice surface albedo significantly. In this paper, comparison is carried out among the three melt pond parameterization schemes in CICES. 0. The results show that each scheme owns strengths and weaknesses. The freezing conditions of the cesm scheme are more reasonable. Comparatively, for the topo scheme, with freezing conditions changed, the amplitude of inter-annual variability of averaged pond fractions,the melt ponds coverage extent and the length of peak season agree with MODIS results best. In addi- tion,by fixing bugs in CICES. 0,melt water permeating through sea ice is analyzed. This process could cause some side effect; for example,nearly no ponds exist on multi year ice in the lvl scheme. This indicates that the evolution of sea ice permeability or other physical processes remains to be improved in CICE model. Lastly, we gave some discussions for the improvement mainly on the topo scheme.