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XIE Lingling,LI Mingming,LI Min. 2015. Observational analysis of the double-diffusive convection in the deep Canada Basin. Acta Oceanologica Sinica, 34(11):71－79

Observational analysis of the double-diffusive convection in the deep Canada Basin

加拿大海盆深层双扩散对流的观测分析

Received:March 19, 2015 Revised:July 04, 2015

DOI：10.1007/s13131-015-0750-4

Key words:double diffusion Canada Basin staircase heat flux water mass

中文关键词: 双扩散加拿大海盆阶梯结构热通量水团

基金项目:The National Natural Science Foundation of China under contract Nos 41476009, 41106012 and 41506018; the Science and Technology Program in Higher Education of Guangdong under contract No. 2013KJCX0099.

Author Name	Affiliation	E-mail
XIE Lingling	Guangdong Province Key Laboratory for Coastal Ocean Variation and Disaster Prediction (GLOD), Guangdong Ocean University, Zhanjiang 524088, China
LI Mingming	Guangdong Province Key Laboratory for Coastal Ocean Variation and Disaster Prediction (GLOD), Guangdong Ocean University, Zhanjiang 524088, China
LI Min	Guangdong Province Key Laboratory for Coastal Ocean Variation and Disaster Prediction (GLOD), Guangdong Ocean University, Zhanjiang 524088, China	mingming.li@vip.126.com

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Abstract:

The Canada Basin (CB) is the largest sub-basin in the Arctic, with the deepest abyssal plain of 3 850 m. The double-diffusive process is the possible passage through which the geothermal energy affects the above isolated deep waters. With the temperature-salinity-pressure observations in 2003, 500-m-thick transition layers and lower 1 000-m-thick bottom homogenous layers were found below 2 400 m in the central deep CB. Staircases with downward-increasing temperature and salinity are prominent in the transition layers, suggesting the double-diffusive convection in deep CB. The interface of the stairs is about 10 m thick with 0.001-0.002℃ temperature difference, while the thicknesses of the homogenous layers in the steps decrease upward from about 60 to 20 m. The density ratio in the deep central CB is generally smaller than 2, indicating stronger double-diffusive convection than that in the upper ocean of 200-400 m. The heat flux through the deepest staircases in the deep CB varies between 0.014 and 0.031 W/m², which is one-two orders smaller than the upper double-diffusive heat flux, but comparable to the estimates of geothermal heat flux.

中文摘要:

加拿大海盆是北冰洋最大的亚海盆,其最深处达到3850 m. 双扩散对流过程可能是底部热通量对海盆内部孤立水体施加影响使水团性质发生变化的主要通道.本文利用2003年中国第二次北极科学考察获得的温盐深观测数据,发现在加拿大海盆中心2400 m以深存在温盐同时随深度增加的过渡层和温盐相对均匀的底部混合层,其平均厚度分别约为500 m和1000 m.在过渡层,双扩散对流引起了明显的温度阶梯结构,阶梯的均匀层厚度由下层的60 m减小到20 m,其界面厚度在10 m左右,温差在0.001-0.002 ℃.海盆深层的密度率基本小于2,双扩散强度大于上层200-400 m处的扩散对流.海盆内部最深层阶梯的热通量为0.014-0.031 W m^-2,比上层双扩散对流的热通量小1-2个量级,但与地热通量的估算值相当.

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