Spreading and salinity change of North Pacific Tropical Water in the Philippine Sea
Spreading and salinity change of North Pacific Tropical Water in the Philippine Sea
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DOI：
10.1007/s10872-012-0110-3
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发表时间：
2012-05
影响因子：
2.3
通讯作者：
Yuanlong Li;Fan Wang
中科院分区：
文献类型：
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作者：
Yuanlong Li;Fan Wang
新形成的北太平洋热带水（NPTW）被北赤道流（NEC）带到菲律宾海（PS）作为次表层盐度最大值。在这项研究中，它的蔓延和盐度变化过程进行了探讨，使用现有的水文数据库2009年和Argo浮标。北太平洋暖流的传播与北太平洋暖流、棉兰老海流和黑潮的输送密切相关。对于盐度S大于34.8 psu的次表层水，8°N（18°N）的MC（黑潮）对NPTW的南（北）向地转输送约为4.4（5.7）Sv（1 Sv = 106 m3 s −1），这对参考层的选择并不敏感。盐度最大值、地转流、海平面变化和位涡的场表明，北太平洋暖流向赤道向热带的传播主要是由中尺度环流提供的，而其向极地的传播则是由黑潮沿沿着的输送和北方太平洋中尺度涡旋通量共同实现的。《核武器条约》在《和平与安全条约》中也经历了显著的更新。位于淡水表层之下，盐度在NPTW的上部下降较快，这使得NPTW的盐度最大值逐渐降低到密度较高的等密度线。在MC中盐度下降特别快，沿程下降速率达到O（10− 7 psu s−1）。由于棉兰老涡附近的盐度梯度增强，在MC中的diapycnal和isopycnal混合效应被证明是升高的。这些结果表明，强烈的分散的热异常沿着的副热带-热带温跃层水路径附近的西部边界。
Newly formed North Pacific Tropical Water (NPTW) is carried to the Philippine Sea (PS) by the North Equatorial Current (NEC) as a subsurface salinity maximum. In this study its spreading and salinity change processes are explored using existing hydrographic data of the World Ocean Database 2009 and Argo floats. Spreading of NPTW is closely associated with the transports of the NEC, Mindanao Current (MC), and Kuroshio. Estimated for subsurface water with salinitySgreater than 34.8 psu, the southward (northward) geostrophic transport of NPTW by the MC (Kuroshio) at 8°N (18°N) is about 4.4 (5.7) Sv (1 Sv = 106m3s−1), which is not sensitive to reference level choice. Fields of salinity maximum, geostrophic current, sea level variation, and potential vorticity suggest that the equatorward spreading of NPTW to the tropics is primarily afforded by the MC, whereas its poleward spreading is achieved by both the Kuroshio transport along the coast and open-ocean mesoscale eddy fluxes in the northern PS. The NPTW also undergoes a prominent freshening in the PS. Lying beneath fresh surface water, salinity decreases quicker in the upper part of the NPTW, which gradually lowers the salinity maximum of NPTW to denser isopycnals. Salinity decrease is especially fast in the MC, with along-path decreasing rate reachingO(10−7psu s−1). Both diapycnal and isopycnal mixing effects are shown to be elevated in the MC owing to enhanced salinity gradient near the Mindanao Eddy. These results suggest intensive dispersion of thermal anomalies along the subtropical-to-tropical thermocline water pathway near the western boundary.