摘要
【目的】研究Merantia、Malaks、Megi、Chaba4个连续台风引起上层海洋的响应。【方法】基于遥感和再分析数据,分析台风前海洋环境、台风做功(W)、强迫时间(tf)、降水等要素分布特征,探讨上层海洋稳定度、上升流、湍流混合动力机制如何影响中尺度涡区域的海表温度(SST)、浮游植物繁殖程度,引入动力学参数S判断海洋内部上升流和混合重要性。【结果和结论】冷涡(CE)区域海洋表层降温(SSC)(3.5℃)和叶绿素a(Chl-a)质量浓度(0.5mg/m3)对于台风响应比暖涡(AE)区更为剧烈,与其内部热力学结构有关,出现在Megi过境CE区,主要原因是海洋本身CE特征、强上升流(EPV)=2.5×10-4 m/s,S<1,台风向海洋输入巨大的能量(W>80 kJ)引起剧烈的混合夹卷、强降雨,导致海水迅速重新层化、逐渐加强的非线性CE有更强的封闭性,这些机制的共同作用将底层(营养盐跃层100m以下)富含营养盐的冷水输送到上层;Malaks过境CE(124.9°E,22.3°N)缺乏强上升流(EPV=5×10-5 m/s),以湍流混合为主(S>1);Merantia使CE区域表现下沉流(EPV<0),SSC主要是湍流混合的作用(W>25kJ),Chl-a浓度增长到0.27mg/m3。AE热力学结构比较稳定,连续台风导致SSC<2℃,Chl-a增加仅200%,Merantia、Malaks过境AE(125.1°E,20.6°N)分别以强上升流(S<1)和湍流混合(S>1)为主,混合层厚度约80 m,同时AE周围无强障碍带,易与周围水体交换,Chl-a浓度微弱增加。
【Objectives】To study the upper ocean response to sequential typhoons(i.e. Merantia, Malaks, Megi and Chaba), based on remote sensing and previous data. 【Method】By analyzing the ocean environmental data before the approaching of typhoons, typhoon work(W), forcing time(tf), precipitation and other characters discussed upper ocean stability, upwelling, and study how turbulent mixing mechanism influence sea surface temperature(SST), phytoplankton bloom and by judging the importance of upwelling and mixing using kinetic parameters S.【Result and Conclusion】The cold eddy(CE) regional SST cooling(SSC)(3.5 ℃) and Chlorophyll-a(Chl-a) concentration(0.5 mg/m3) are more intense than the warm eddy(AE) when Megi transited the CE region, mainly due to the CE characteristics, strong upwelling [Ekman pumping velocity(EPV) = 2.5×10-4 m/s, kinetic parameter S < 1], the input of huge energy(W > 80 kJ) into the ocean and strong rainfall caused rapid re-stratification, and the gradual strengthening of nonlinear CE had stronger sealing. The combination of these mechanisms can mobilize the bottom nutrient-rich layer(nutrient halocline below 100 m) of cold water to the upper level of Malaks and Merantia kept CE(124.9°E,22.3°N)weak upwelling(EPV = 5×10-5 m/s), downwelling(EPV < 0), respectively, mainly turbulent mixing(S > 1), so SSC was mainly turbulent mixed effect(W > 25 kJ), Chl-a increased to 0.27. The thermodynamic structure of AE was relatively stable. Sequential typhoons has leaded to SSC < 2 ℃, and the increase of Chl-a was only 200%, AE(125.1°E, 20.6°N)were mixed with weak upwelling(S < 1) and turbulent mixing respectively(S > 1) were dominant during Merantia and Malaks, mixed layer depth was 80 m, and there was no strong obstacle zone around AE, which was easy to exchange with surrounding water bodies, and Chl-a showed a slight increase.
作者
王同宇
张书文
陈法锦
蒋晨
马永贵
WANG Tong-yu;ZHANG Shu-wen;CHEN Fa-jin;JIANG Chen;MA Yong-gui(Guangdong Key Laboratory of Coastal Ocean Variation and Disaster Prediction,College of Ocean and Meteorology,Guangdong Ocean University,Zhanjiang 524088,China;College of Science,Shantou University,Shantou 515063,China)
出处
《广东海洋大学学报》
CAS
2019年第6期62-74,共13页
Journal of Guangdong Ocean University
基金
国家重点研发计划重点专项(2016YFC14001403)
国家自然科学基金面上项目(41676008和41876005)
国际合作项目(GASI-IPOVI-04)
广东省自然科学基金(2016A030312004)
关键词
连续台风
中尺度涡
海洋响应
上升流
混合
西太平洋
sequential typhoons
mesoscale eddy
upper ocean response
upwelling
mixing
Northwest Pacific Ocean
