Spatial Distribution and Seasonality of Halocline Structures in the Subarctic North Pacific
Spatial Distribution and Seasonality of Halocline Structures in the Subarctic North Pacific
复制标题
北太平洋亚北极盐跃层结构的空间分布和季节性
DOI：
10.1175/jpo-d-19-0133.1
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发表时间：
2020
影响因子：
3.5
通讯作者：
S. Kouketsu
中科院分区：
文献类型：
--
作者：
Katsura;S.;H. Ueno;H. Mitsudera;S. Kouketsu
利用2003 - 2017年Argo剖面浮子资料和各种地表通量资料，研究了亚北极北太平洋盐斜结构的空间分布和季节性。永久盐跃层在深度和强度的空间分布上呈带状分布，东部呈浅强，西部呈深弱。PH深度和强度的平均分布分别与冬季混合层深度和海面盐度相对应，表明其与冬季混合层的发育有关。在形成较强PH的亚北极西部环流和阿拉斯加环流中，PH强度和深度呈现明显的季节变化，冷却期混合层的加深压缩了下伏PH，导致PH在冬末增强和发展。在这两个地区，高盐度水的上涌也导致了PH的加剧。夏季盐跃层在频率和强度上存在明显的地带性差异，与PH分布相反。在西南偏西、中部和沿海地区形成了沙暴，而东部地区很少出现沙暴。SH的纬向对比与增暖期混合层的变新鲜相对应，主要反映淡水通量。地转和Ekman平流在SH强度和深度的空间差异中起重要作用。在接下来的冬季，SH的发展通过夹带降低高于PH的盐度，从而加剧了PH。
The spatial distribution and seasonality of halocline structures in the subarctic North Pacific (SNP) were investigated using Argo profiling float data and various surface flux data collected in 2003–17. The permanent halocline (PH) showed zonal patterns in the spatial distributions of its depth and intensity and tended to be shallow and strong in the eastern SNP but deep and weak in the west. Mean distributions of PH depth and intensity corresponded to the winter mixed layer depth and sea surface salinity, respectively, indicating that it forms in association with the development of the winter mixed layer. In the Western Subarctic Gyre and Alaskan Gyre, where a relatively strong PH formed, PH intensity and depth showed clear seasonal variations, and deepening of the mixed layer compressed the underlying PH during the cooling period, resulting in intensification and development of the PH in late winter. In both regions, upwelling of high-salinity water also contributed to PH intensification. The summer seasonal halocline (SH) showed distinct zonal differences in frequency and intensity, which were opposite to the PH distribution. While an SH formed in the western and central SNP and coastal regions, it was seldom present in the eastern area. This zonal contrast of SH corresponded to freshening of the mixed layer during the warming period, primarily reflecting freshwater flux. Geostrophic and Ekman advection play important roles in spatial differences in SH intensity and depth. SH development contributed to PH intensification in the following winter, by decreasing salinity above the PH through entrainment.