21世纪格陵兰冰川融化速率对海平面变化的影响

The influence of the melting rate of the Greenland ice sheet on the sea level variation for 21st century

本文利用大洋环流模式POP研究RCP4.5情景下21世纪格陵兰冰川不同的融化速率对全球及区域海平面变化的影响。结果显示:当格陵兰冰川的融化速率以每年1%增加时,全球大部分海域的动力和比容海平面变化基本不变,主要是由于格陵兰冰川在低速融化时并不会导致大西洋经向翻转流减弱。当格陵兰冰川的融化速率以每年3%和每年7%增加时,动力海平面在北大西洋副极地、大西洋热带、南大西洋副热带和北冰洋海域呈现出显著的上升趋势,这是因为格陵兰冰川快速融化导致大量的淡水输入附近海域,造成该上层海洋层化加强和深对流减弱,导致大西洋经向翻转流显著减弱;与此同时,热比容海平面在北冰洋、格陵兰岛南部海域和大西洋副热带海域显著下降,而在热带大西洋和湾流海域明显上升;此时盐比容海平面的变化与热比容海平面是反相的,这是由于大量的低温低盐水的输入,造成北大西洋副极地海域变冷变淡、大西洋经向翻转流和热盐环流显著减弱,引起了太平洋向北冰洋的热通量和淡水通量减少,导致了北冰洋海水变冷变淡,同时热带大西洋滞留了更多的高温高盐水,随着湾流被带到北大西洋,北大西洋副极地海域低温低盐的海水,被风生环流输运到副热带海域。

The influence of the different melting rate of Greenland ice sheet on sea level of the global and regional ocean are studied based on POP model under the RCP4.5scenario for the 21 st century.In the 21 st century,the low melting rate of Greenland ice sheet has small influence on the global and regional sea level variations,which mainly due to the meridional overturning flow doesnt weak under the low melting rate of Greenland ice sheet in the Atlantic.The high melting rate will have notably effect on the dynamic and steric sea level in the Atlantic,the Arctic and Antarctic Circumpolar Current（ACC）.The dynamic sea level will significantly rise in the north Atlantic subpolar Ocean,tropical Atlantic Ocean,the south Atlantic subtropical and Arctic Ocean,which will rise fast in ocean of southern Greenland and along the coast of North America,that is due to notable weakened of the meridional overturning flow caused by strengthen stratification of the upper ocean and deep convection weakened because of a lot of fresh water input Greenland nearby ocean in the high rate of melting of Greenland ice sheet,namely the labrad or current will strengthen,the Gulf Stream and the north Atlantic current weakened.The thermosteric sea level will significantly decline in the Arctic ocean,the ocean of the southern Greenland and the Atlantic subtropical ocean,while which obviously rise the tropical Atlantic ocean and the Gulf Stream.Meanwhile the halosteric sea level change will be opposite to the thermosteric sea level.The steric sea level showed change due to the water is cooling and thin in the north Atlantic subpolar ocean,the weakened of the Atlantic meridional overturning flow and thermohaline circulation caused by input of lot of low temperature and low salt water in the 21 st century.