Water column structure and circulation under the North Water during spring transition:: April-July 1998
Water column structure and circulation under the North Water during spring transition:: April-July 1998
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DOI：
10.1016/s0967-0645(02)00170-4
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发表时间：
2002-01-01
影响因子：
3
通讯作者：
Ingram, RG
中科院分区：
文献类型：
--
作者：
Bâcle, J;Carmack, EC;Ingram, RG
北水是巴芬湾北部一个反复出现的大冰湖。在1998年4月至7月期间，研究人员分析了多个监测站采集的400多条水文CTD剖面，以了解春季过渡期间多冰湖下面的水柱结构。在北水，进口的和不同的水团聚集在一个复杂的水深测量上：北集合（NA）水来自通过纳尔斯海峡和琼斯湾的流入；南集合（SA）水是由西格陵兰流（WGC）的一个向北移动的分支形成的。南水北调和南水北调主要在北纬76.5度和77度之间的南北史密斯海峡峡谷上空混合，形成一个明显的、相对较厚的盐斜层（称为“北水组合”，NWA），其特征是密度补偿的温盐侵入。在北水的南部，NWA水域和SA水域之间的尖锐锋面大致与500米等深线对齐。从潜在温度与盐度（θ - S）图和最小稳定频率(N)剖面中推断出的流动模式表明，该锋面是由NWA水域和WGC分支的汇合造成的，当它接近史密斯湾峡谷时，WGC分支被旋风重新导向。并不是所有的南太平洋水域都会立即向南转向，因为第二个分支沿着格陵兰海岸流向史密斯湾。虽然θ - S信号显示了格陵兰海岸上升流的一些证据（例如，等平面露出海面），但在采样期间（1998年）没有观察到来自大西洋的温暖水的表面，这表明风和洋流机械地去除冰是北水形成的主要机制。一些与盐水排出和穿透对流相关的显热交换可能发生，但仅在活跃冰形成期间发生。(C) 2002 Elsevier Science Ltd.版权所有。
The North Water is a large recurring polynya in northern Baffin Bay. Over 400 hydrographic CTD profiles taken over a grid of stations between April and July 1998 were analysed to understand the water-column structures underlying the polynya during spring transition. In the North Water, imported and dissimilar water masses converge over a complex bathymetry: Northern assembly (NA) waters are derived from inflows through Nares Strait and Jones Sound; Southern assembly (SA) waters are derived from a northern-moving branch of the West Greenland Current (WGC). NA and SA waters mix primarily over the north-south Smith Sound Canyon, between 76.5degreesN and 77degreesN latitude, to form a distinct, relatively thick halocline layer (termed 'North Water assembly', NWA), characterised by density-compensating thermohaline intrusions. In the southern portion of the North Water, a sharp front between NWA waters and SA waters roughly aligns with the 500-m isobath. Flow patterns, deduced from potential temperature vs. salinity (theta - S) diagrams and from minima in stability frequency (N) profiles, indicate that this front results from the convergence of NWA waters and a branch of the WGC that is cyclonically re-directed as it approaches Smith Sound Canyon. Not all SA waters are immediately re-directed south towards the front, as a second branch follows the Greenland coast toward Smith Sound. While theta - S signatures show some evidence of upwelling along the Greenland coast (e.g. outcropping of isopycnal surfaces), no surfacing of warm Atlantic-derived water was observed during the sampling period (1998), suggesting that mechanical removal of ice by winds and currents is the primary mechanism by which the North Water forms. Some sensible heat exchange associated with brine rejection and penetrative convection may occur, but only during periods of active ice formation. (C) 2002 Elsevier Science Ltd. All rights reserved.