2008年加拿大海盆次表层暖水的精细结构的研究

摘要

自2004年以来,在加拿大海盆频繁发生的次表层暖水(near surface temperature maximum,NSTM)现象是北极快速变化响应的事实之一.采用2008年中国第3次北极科学考察的CTD数据和西北冰洋联合研究计划与美国波弗特环流观测系统计划2008年航次的CTD数据以及冰浮标ITP18数据,对加拿大海盆的NSTM现象进行了精细结构的分析.结果表明,NSTM的温度垂直结构与海冰关系密切,在海冰密集度较大的区域,发展成熟的NSTM的盐跃层稳定,温度极大值均小于-1.0℃,而且垂向温度结构差异不大,多为典型的单峰结构;在海冰边缘区和开阔水域,由于受气象条件的影响较大,盐跃层不十分稳定,温度极大值和温度的垂向分布差异较大,常出现双峰甚至多峰结构.NSTM温度极大值出现的深度不仅与NSTM发生、发展的时间有关,而且与纬度有关,纬度越高,深度越深.NSTM的发生、发展和消衰的时间尺度为1 a,夏季发生,秋季和冬季不断向表层和下层传递热量,温度峰值变小,第二年的春季消失.%The phenomena of near surface temperature maximum (NSTM) occurred continually in the Canada Basin from 2004, which is one of the responses to the rapid change of the arctic.The fine structures of the NSTM are studied using the CTD data by the third National Arctic Research expedition of China (CHINARE) and the joint west arctic climate study (JWACS) and the Beaufort Gyre exploration project (BGEP) and ITP18 data collected in 2008 in the Canada Basin.The vertical properties of the NSTM are related to the sea ice.In the sea ice covered area there is little difference of the NSTM.But the differences of the maximum of temperature and the vertical structures of the NSTM are obvious in the marginal ice zone and the open water.The maximum temperature and the corresponding depth are related to not only the period of the NSTM, but the latitude of stations.The higher the latitude, the deeper the corresponding depth of the maximum temperature of the NSTM.The annual period of the NSTM is shown by ITP data, which occurrs in summer and disappears in spring in next year.