2012年北冰洋大气旋对楚科奇海水团和环流的影响

The Chukchi Sea is not only an important exchange channel of water volume and heat between the Arctic and Pacific Oceans, but also the main source region of heat and fresh water for the Arctic. Study on the variations of water masses and circulation in the Chukchi Sea will improve the understanding on the changes of sea ice, climate and ecosystem with the dramatically rapid change in the Arctic. The Great Arctic Cyclone of 2012 (GAC-2012), which was observed in early August 2012, is the strongest summer cyclone since the beginning of satellite observations in 1979. A mooring system employed in the central Chukchi Sea during the fifth Chinese Arctic Research Expedition (CHINARE-5) recorded the entire varying procedure of the changes of water mass and circulation characteristics induced by GAC-2012. In this study, by means of data analyzing and numerical modeling, the mooring observations obtained in CHINARE-5 and other open data will be used to analyze the temporal and spatial characteristics and the affecting factors of water masses and circulation under the influenced of GAC-2012. Numerical experiments will be designed to explore the influence mechanism of summer cyclones on the thermodynamics and dynamics of the Chukchi Sea. This project will place a firm foundation for the further research on the rapid change of the Arctic, ecosystem and global climate evolution.

楚科奇海是北冰洋与太平洋水热交换的重要通道，也是北冰洋热量和淡水的主要源地。研究楚科奇海水团和环流特征变化可以加深对北极快速变化背景下海冰、气候和生态系统变化的认识，为深入研究北极在全球气候变化中的作用奠定基础。2012年8月上旬北冰洋经历了卫星观测历史以来最强的一次夏季气旋天气过程，被称为2012年北冰洋大气旋。我国第五次北极考察期间布放于楚科奇海中部海域的潜标系统完整记录了该气旋过境时海洋水团和环流特征的变化信息。本项目拟利用五北潜标数据并结合国内外公开数据，通过数据分析和数值模拟，分析气旋影响下楚科奇海水团和海流时空变化特征及影响因素，设计数值实验研究气旋对楚科奇海热力学和动力学的影响机制。本项目将对北极快速变化、生态系统改变以及全球气候演变有着基础性的研究价值。

随着北极气候的快速变化，海冰缩减，海-气相互作用愈发剧烈。2012是不可忽视的特殊年份，北极海冰达到了卫星观测历史以来面积最小值，8月份爆发了十分罕见的“2012年北冰洋大气旋”，海洋环境变化显著。本项目按照研究目标和计划，搜集整理了我国第二次至第九次北极考察航次在楚科奇海的3条经向断面和1条纬向断面的观测数据并进行了深入分析，掌握了楚科奇海各主要水团的分布和变化特征。建立了双层嵌套模型模拟楚科奇海水团和环流特征，重构了气旋影响下的海洋变化过程，分析了该过程中楚科奇海的上层海洋垂向混合、水团和环流空间分布和特征、水体通量变化等过程。通过设置不同的数值试验，分析了有无气旋影响下各种物理过程对楚科奇海温度、盐度和海流变化的作用。明确了观测期间各阶段气旋对楚科奇海水团和环流影响的动力机制。