Bottom water temperature measurements in the South China Sea,eastern Indian Ocean and western Pacific Ocean

文章报道了一批新的海底底水温度(BWT)数据,其中南海(SCS)158个站位、东印度洋(EIO)30个站位及西太平洋(WPO)37个站位。基于这批新的BWT数据,获得南海和西太平洋海域底水温度与水深经验关系,可为地球物理和物理海洋提供准确、可靠的海底温度边界。这将有助于海底油气资源调查与评估。同时,这批实测数据表明:1)水深超过3500m的海域,其底水温度在南海约为2.47℃,比东印度洋(～1.34℃)和西太平洋(～1.60℃)稍微偏高。这与大洋传送带模式所预测的情况比较吻合。该模式认为:低温高盐的海水,从北大西洋格陵兰岛和冰岛附近海域下沉到深层,然后向南流动,再与南极洲周围海域的低温高盐海水一同向北进入印度洋和太平洋。而南海是一个相对比较封闭的热带边缘海,其内部海水与印度洋和菲律宾海交换有限,导致海水温度整体高于印度洋和太平洋。2)台西南盆地水深在2700～3000m的部分站位,其底水温高达约3.00℃,明显高于其周边同水深海域底水温度(平均值约为2.33℃)。这可能是台西南盆地海底水热活动导致的结果。3)在东印度洋和西太平洋水深超过4800m海域,底水温度随着水压增大稍有升高,其升高率分别为10.6mK·MPa^(-1)和12.0mK·MPa^(-1)。这与理论估算的深层底水绝热压力温度梯度范围较为吻合。这也意味着东印度洋和西太平洋深层底水,主要由绝热自压作用导致其温度随着深度的增大而升高。

In this paper,we reported the latest bottom water temperature(BWT)data,from 158 stations in the South China Sea(SCS),30 stations in the eastern Indian Ocean(EIO)and 37 stations in the western Pacific Ocean(WPO).Based on the new data in the SCS and WPO,we obtained good empirical relationships between BWT and water depth.They can provide accurate and reliable boundary conditions for geophysics and physical oceanography in the SCS and WPO.Furthermore,it will be very helpful for the investigation and assessment of oil and gas resources in the oceans.The measured BWT in the SCS(~2.47°C)is higher than that in the EIO(~1.34°C)and WPO(~1.60°C)where the water depth is deeper than 3500 m.This is consistent with the model of the great ocean conveyor belt since the cold and saline deep water,which is from Greenland,Iceland in the North Atlantic and the sea area around the Antarctica,enters the Indian and Pacific oceans from the south.In the Southwest Taiwan Basin,the BWTs at several stations are around 3.00°C,which is clearly higher than the average value(~2.33°C)at other stations with the same water depth range(2700~3000 m)in this basin.The local high anomaly of BWT is probably caused by the hydrothermal activity in the Southwest Taiwan Basin.In the EIO and WPO,the BWT increases slightly at the rates of 10.6 mK·MPa-1 and 12.0 mK·MPa-1,respectively,when the water depth is deeper than 4800 m.The rising rates are consistent with the estimated adiabatic pressure derivative of the temperature of the deep bottom water.It indicates that the BWT rising is mainly caused by the adiabatic compression in the deep water.