Spatial and temporal variability of the North Korean Cold Water leading to the near-bottom cold water intrusion in Korea Strait
Spatial and temporal variability of the North Korean Cold Water leading to the near-bottom cold water intrusion in Korea Strait
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朝鲜冷水时空变化导致朝鲜海峡近海底冷水入侵
DOI：
10.1016/j.pocean.2003.11.004
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Sang
中科院分区：
文献类型：
--
作者：
Jae;L. Magaard;Kuh Kim;C. Shin;Cheolsoo Kim;Sang
在朝鲜海峡最深处，表层温度在8月最高（3月最低），而近底层温度在9月最低（5月最高）。对两层月平均气温资料的交叉谱分析表明，在年频率上有很高的相干性，相位为154°。为什么以及如何在表面和近底部温度之间发生这种几乎相反的相位？本研究旨在利用历史和最近观察到的数据回答这些问题。寒冷而相对新鲜的地下水沿着沿着朝鲜东海岸向南流动，被称为朝鲜冷水（NKCW），在4月的索乔海岸附近变得明显。6月前后纬向温度梯度最大。NKCW的宽度从4月到8月变得更大。10月后，NKCW撤回海岸。因此，NKCW向南的移动在六到七个月的时间里是很强的，在冬季，特别是在二月，很弱。北九龙西流于4月至10月沿海岸沿着向南流动，并于1至2个月内抵达郁陵岛盆地。由于郁陵海盆和朝鲜海峡之间有岩床，这些水不能继续向南流动，而是堆积了大约两到三个月才越过岩床。郁陵岛盆地地下冷水的汇聚使等密度线向上移动，然后沿沿着等密度线侵入岩床。因此，在索乔沿岸明显出现这种水的4月或5月，朝鲜海峡的近底层水温度最高;在郁陵海盆南端堆积的NKCW侵入朝鲜海峡的8月或9月，近底层水温度最低。NKCW的来源可能是1 ~ 3月在东海西北部下沉的盐度小于34.1psu、面密度大于27σθ的水。冬季地面冷却是导致水体下沉的主要原因，而强烈的负风应力旋度又使下沉加剧。形成于东海西北部的寒冷而相对新鲜的海水，被假设沿着韩国东海岸、郁陵岛北部的水道、以及郁陵岛和独岛之间的水道三条主要路径流向郁陵岛盆地。
In the deepest region of Korea Strait, the surface temperature is highest in August (lowest in March), while the near-bottom temperature is lowest in September (highest in May). Cross-spectral analysis of the monthly temperature data between the two layers shows high coherence at the annual frequency with phase of 154°. Why and how does such a nearly opposite phasing occur between the surface and the near-bottom temperatures there? This study aims at answering these questions using historical and recently observed data. Cold and relatively fresh subsurface water flowing southward along the east coast of Korea and, known as the North Korean Cold Water (NKCW), becomes noticeable in April near the Sokcho coast. The zonal temperature gradient there is largest around June. The width of the NKCW becomes larger from April to August. After October, the NKCW retreats back toward the coast. The southward movement of the NKCW is thus strong over a period of six to seven months and weak in winter, especially in February. The NKCW flows southward relatively quickly along the coast in April to October and arrives at the Ulleung Basin within one to two months. Because of the sill between the Ulleung Basin and Korea Strait, this water cannot continue to flow to south, but piles up for about two to three months before it moves over the sill. The convergence of the subsurface cold water in the Ulleung Basin displaces the isopycnals upward and this water then intrudes over the sill along the isopycnals. This explains why in April or May, when this water appears noticeably at the Sokcho coast, the near-bottom water in Korea Strait is warmest and in August or September when the NKCW, which is piled up enough at the southern end of the Ulleung Basin, intrudes to Korea Strait, the near-bottom temperatures there are at their lowest. The origin of the NKCW seems to be the water of salinity less han 34.1 psu and surface density of 27σθor higher, which sinks in the northwestern East Sea in January–March. The sinking of the water results from surface cooling in winter and is intensified due to the strong negative windstress curl. The cold and relatively fresh water, formed in the northwestern East Sea, is hypothesized to flow to the Ulleung Basin along three major paths, along the east coast of Korea, through the channel north of Ulleung-do Island, and through the channel between Ulleung-do and Dok-do Islands.