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GUO Guijun,SHI Jiuxin,JIAO Yutian. 2015. Temporal variability of vertical heat flux in the Makarov Basin during the ice camp observation in summer 2010. Acta Oceanologica Sinica, 34(11):118-125
Temporal variability of vertical heat flux in the Makarov Basin during the ice camp observation in summer 2010
2010年马卡罗夫海盆冰站观测期间垂向热通量时间变化研究
Received:June 02, 2014  Revised:June 11, 2015
DOI:10.1007/s13131-015-0755-z
Key words:sea ice  heat flux  remnant of winter mixed layer  heat content  Makarov Basin
中文关键词:  海冰  热通量  冬季混合层残留水  热含量  马卡罗夫海盆
基金项目:The Global Change Research Program of China under contract No. 2015CB953902; the National Natural Science Foundation of China under contract Nos 41330960 and 40976111.
Author NameAffiliationE-mail
GUO Guijun College of Physical and Environmental Oceanography, Ocean University of China, Qingdao 266100, China
Key Laboratory of Physical Oceanography, Ministry of Education, Qingdao 266003, China 
 
SHI Jiuxin College of Physical and Environmental Oceanography, Ocean University of China, Qingdao 266100, China
Key Laboratory of Physical Oceanography, Ministry of Education, Qingdao 266003, China 
shijiuxin@ouc.edu.cn 
JIAO Yutian College of Physical and Environmental Oceanography, Ocean University of China, Qingdao 266100, China
Key Laboratory of Physical Oceanography, Ministry of Education, Qingdao 266003, China 
 
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Abstract:
      Based on hydrographic data obtained at an ice camp deployed in the Makarov Basin by the 4th Chinese Arctic Research Expedition in August of 2010, temporal variability of vertical heat flux in the upper ocean of the Makarov Basin is investigated together with its impacts on sea ice melt and evolution of heat content in the remnant of winter mixed layer (rWML). The upper ocean of the Makarov Basin under sea ice is vertically stratified. Oceanic heat flux from mixed layer (ML) to ice evolves in three stages as a response to air temperature changes, fluctuating from 12.4 W/m2 to the maximum 43.6 W/m2. The heat transferred upward from ML can support (0.7±0.3) cm/d ice melt rate on average, and daily variability of melt rate agrees well with the observed results. Downward heat flux from ML across the base of ML is much less, only 0.87 W/m2, due to enhanced stratification in the seasonal halocline under ML caused by sea ice melt, indicating that increasing solar heat entering summer ML is mainly used to melt sea ice, with a small proportion transferred downward and stored in the rWML. Heat flux from ML into rWML changes in two phases caused by abrupt air cooling with a day lag. Meanwhile, upward heat flux from Atlantic water (AW) across the base of rWML, even though obstructed by the cold halocline layer (CHL), reaches 0.18 W/m2 on average with no obvious changing pattern and is also trapped by the rWML. Upward heat flux from deep AW is higher than generally supposed value near 0, as the existence of rWML enlarges the temperature gradient between surface water and CHL. Acting as a reservoir of heat transferred from both ML and AW, the increasing heat content of rWML can delay the onset of sea ice freezing.
中文摘要:
      本文利用2010年8月中国第四次北极考察期间在马卡罗夫海盆布设的长期冰站获得的数据,对马卡罗夫海盆冰下上层海洋热通量时间变化规律及其对海冰融化和冬季混合层残留水热含量发展过程的影响进行了研究.在冰站漂流期间,马卡罗夫海盆冰下上层海洋呈现出明显的垂向层化特征.受大气温度变化影响,混合层海水向海冰输送的热通量随时间呈现出了三个不同的发展阶段,在12.4 W·m-2到43.6 W·m-2的范围内波动.混合层向海冰输送的热量平均每天可以融冰(0.7±0.3) cm,海冰融化速度日变化与实测结果相吻合.同时,受夏季融冰的影响,混合层之下的季节性盐跃层层化加强,导致混合层海水穿过混合层底向下的热通量相对较小,只有0.87 W·m-2,说明进入夏季混合层的太阳辐射主要用于融冰,只有一小部分向下输送储存在冬季混合层残留水中.受观测期间大气急剧降温过程的影响,混合层海水穿过混合层底向冬季混合层残留水的热通量分化成了两个不同的发展阶段,相对大气降温存在着一天的滞后.虽然冷盐跃层的存在制约着大西洋水穿过冬季混合层残留水底部向上的热量输送,该界面向上的热通量依然达到了0.18 W·m-2并存储在冬季混合层残留水中.大西洋水向上的热通量一般认为接近于0,在此显著的原因在于冬季混合层残留水的存在增大了上层海水和冷盐跃层之间的温度梯度.冬季混合层残留水作为混合层海水和大西洋水热量输送的蓄热层,其热含量的累积会延迟冬季结冰过程的开始.
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