Seasonal thermocline in the China Seas and northwestern Pacific Ocean
Seasonal thermocline in the China Seas and northwestern Pacific Ocean
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DOI：
10.1029/2011jc007246
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发表时间：
2012-02-11
影响因子：
3.6
通讯作者：
Lin, Pengfei
中科院分区：
文献类型：
--
作者：
Hao, Jiajia;Chen, Yongli;Lin, Pengfei
利用1930-2001年(707,624条)的历史资料，研究了中国海和西北太平洋温跃层的气候季节变化。利用浮力比(R=|B-Q/B-p|)和Monin-Obukhov深度比(Delta)，分别探讨了不同季节和不同区域地表热浮力(B-q)、盐度浮力通量(B-p)和总浮力通量(B)对风致混合(Tau)的定量作用。北纬20度以北温跃层具有明显的季节变化，渤海西岸、黄海西岸和东中国海北部12~3月由于表层降温和风的混合，没有温跃层出现。中国陆架内外温跃层强度的显著差异主要是由于陆架上的底潮混合增强了热层结。三角洲表明，夏季中国陆架温跃层深度以B为主，冬季以tau为主。在黑潮地区则表现出相反的特征，冬季的主导因子是B，与那里的大的热浮力损失有关。在北纬20度以南，主导因子与陆架相似，季风过渡期的B主导特征更为明显。R值表明，B主要受B-Q控制，冬季热带地区有零星的B-P控制区，9月BS和YS东部有零星的B-P控制区。
Climatological seasonal variations of the thermocline in the China Seas and northwestern Pacific Ocean were studied using historical data from 1930 through 2001 (707,624 profiles). The quantitative roles of surface thermal buoyancy (B-q), haline buoyancy flux (B-p), and total buoyancy flux (B) against the wind-induced mixing (tau) in different seasons and regions were also explored using the buoyancy ratio (R = |B-q/B-p|) and the Monin-Obukhov depth ratio (delta), respectively. The thermocline has obvious seasonal variations in the study area north of 20 degrees N. There is no thermocline along the west coast of the Bohai Sea (BS), Yellow Sea (YS), and northern East China Sea from December to March resulting from surface cooling and wind mixing. The significantly different variation of the thermocline strength on and off the Chinese shelf is mainly caused by the fact that the thermal stratification is enhanced by bottom tidal mixing on the shelf. The delta indicates that the thermocline depth on the Chinese shelf is mainly dominated by B in summer, while it is dominated by tau in winter. It reveals an opposite feature in the Kuroshio region; the dominating factor is B in winter, associated with the large heat buoyancy loss there. South of 20 degrees N, the dominating factor is similar to that on the shelf, with the more obvious B dominant characteristic during the monsoon transition periods. The R demonstrates that B is mainly controlled by B-q all year round, with some sporadically B-p-dominated regions in the tropical area in winter and in the BS and eastern YS in September.