Characteristics and Transformation of Pacific Winter Water on the Chukchi Sea Shelf in Late Spring
Characteristics and Transformation of Pacific Winter Water on the Chukchi Sea Shelf in Late Spring
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DOI：
10.1029/2019jc015261
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
A. Pacini;G. Moore;R. Pickart;C. Nobre;F. Bahr;K. Våge;K. Arrigo
中科院分区：
文献类型：
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作者：
A. Pacini;G. Moore;R. Pickart;C. Nobre;F. Bahr;K. Våge;K. Arrigo
本文利用楚科奇海东北部的一次晚春调查数据，对新通气冬季水（NVWW）的各个方面进行了研究。在大陆架上取样的水中，超过96%的水是NVWW，其中最咸（密度最大）的水往往位于大陆架上的主要水流路径中。大陆架上几乎所有的水文剖面都显示出两层结构，表面混合层和底部边界层被一个弱密度界面（约0.02 kg/m3）分开。利用多峰模型驱动一维混合模型，结果表明，在3月和4月的热通量作用下，平均14-25小时内，剖面将完全均匀化。当受到5月热通量的影响时，一部分剖面会变得均匀化。由于研究区域在浮冰中包含了大量的铅-其中许多是重新冻结的-并且由于一些测量的剖面在垂直方向上密度是均匀的，这表明整个楚科奇冰架是通过对流在冰的小开口中形成的。这与沿中央陆架路径的NVWW的盐度信号不能仅仅用白令海峡平流或大型冰裂带内的改造来解释的结果一致。预计当地的对流会将沉积物中的营养物质搅拌到水柱中，这就解释了在整个大陆架上观察到的高硝酸盐浓度。这为楚科奇陆架浮游植物的生长提供了有利的初始条件。
Data from a late spring survey of the northeast Chukchi Sea are used to investigate various aspects of newly ventilated winter water (NVWW). More than 96% of the water sampled on the shelf was NVWW, the saltiest (densest) of which tended to be in the main flow pathways on the shelf. Nearly all of the hydrographic profiles on the shelf displayed a two‐layer structure, with a surface mixed layer and bottom boundary layer separated by a weak density interface (on the order of 0.02 kg/m3). Using a polynya model to drive a one‐dimensional mixing model, it was demonstrated that, on average, the profiles would become completely homogenized within 14–25 hr when subjected to the March and April heat fluxes. A subset of the profiles would become homogenized when subjected to the May heat fluxes. Since the study domain contained numerous leads within the pack ice—many of them refreezing—and since some of the measured profiles were vertically uniform in density, this suggests that NVWW is formed throughout the Chukchi shelf via convection within small openings in the ice. This is consistent with the result that the salinity signals of the NVWW along the central shelf pathway cannot be explained solely by advection from Bering Strait or via modification within large polynyas. The local convection would be expected to stir nutrients into the water column from the sediments, which explains the high nitrate concentrations observed throughout the shelf. This provides a favorable initial condition for phytoplankton growth on the Chukchi shelf.