FGOALS_gg1.1极地气候模拟

对中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室发展的气候系统模式FGOALS_g1.1的极地气候模拟现状进行了较为全面的评估.结果表明,FGOALS_g1.1对南北极海冰的主要分布特征、季节变化和年代际变化趋势具有一定的模拟能力.但也注意到,与观测相比,模式存在以下几方面的问题:(1)模拟的海冰总面积北极偏多,而南极偏少.北极,北大西洋海冰全年明显偏多;夏季,西伯利亚沿海海冰偏多,而波弗特海海冰偏少.南极,威德尔海和罗斯海冬季海冰偏少.南北极海冰边缘都存在异常的较大范围密集度很小的碎冰区,夏季尤为显著.(2)海冰流速在南北极海冰边缘和南极大陆沿岸附近较大.北极,模式没能模拟出波弗特涡流,并且由于模式网格中北极点的处理问题,造成其附近错误的海冰流场及厚度分布.这些海冰偏差与模式模拟的大气和海洋状况有着密切的联系.进一步分析表明,FGOALS_g1.1模拟的冰岛低压和南极绕极西风带明显偏弱,其通过大气环流和海表面风应力影响向极地的热量输送,在很大程度上导致上述的海冰偏差.此外,耦合模式中大气-海冰-海洋的相互作用可以放大子模式中的偏差.

Polar climate simulation in FGOALS_g1.1

The polar climate simulations (with emphasis on sea ice) in the latest version of LASG climate system model (FGOALS_ g1.1) were evaluated using a variety of observational data. The results show that FGOALS_g1.1 does a reasonable job in simulating primary characteristics of the Arctic and Antarctic sea ice, including spatial distribution, seasonal variation, and decadal trend. However, some discrepancies are noteworthy. (1) FGOALS_g1.1 produces more (less) total sea ice area in the Arctic (Antarctic) as compared to the observations. In the Arctic, there is excessive (insufficient) ice cover in north Atlantic all year long, and in east Siberia Sea (Beaufort Sea) in summer. In the Antarctic, there is insufficient ice cover in the Weddell and Ross Seas in winter. Extremely large area with small ice concentration is found far beyond the sea ice edge zone in both the Arctic and Antarctic, particularly in summer. (2) The simulated sea ice velocity is systematically too large as compared to the observations, mainly near the sea ice edge in both the Arctic and Antarctic as well as near Antarctic coastal regions. In the Arctic, the model can not capture the Beaufort Gyre, and produce unrealistic ice motion and thickness distribution around the North Pole due to the impropriate way to handle the North Pole. Biases in sea ice simulations identified here are closely associated with how well the simulations are in atmosphere and ocean components of FGOALS_g1.1. Further analyses show that weak Icelandic Low and Antarctic Circumpolar Westerly simulated in FGOALS_g1.1 partly contribute to the aforementioned biases in sea ice simulations through influencing atmospheric and oceanic poleward heat transport. Additionally, the amplification of biases in the subcomponent of FGOALS_g1.1 due to atmosphere-sea ice-ocean interaction is briefly discussed.