基金项目: | Acknowledgments This research was supported by the youth fund of the State Oceanic Administration, People's Republic of China (Grant no. 2010614), the Polar Strategic Research Foundation of China (Grant no. 20100201), the Public Science and Tech- nology Research Funds Projects of Ocean (Grant no. 201005017), the National Natural Science Foundation of China (Grant no. 40874082, 40890164) and the National Basic Research Program of China (Grant no. 2010CB950503-06). |