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南海北部上层细尺度流速剪切的时间变化规律研究

Temporal Variation of Finescale Velocity Shear in the Upper Ocean of Northern South China Sea
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摘要 基于2011年4月至2012年3月南海北部陆坡区潜标观测的高分辨率流速数据,本文研究了海洋上层细尺度流速剪切的时间变化特征及其演变规律。流速剪切的功率谱分析结果显示,南海北部上层的细尺度流速剪切主要受亚惯性运动、近惯性内波、全日内潮和半日内潮四种过程控制。其中,风生近惯性内波和中尺度涡旋所对应的亚惯性运动是造成上层流速剪切时间变化的主要原因,以往研究强调的全日和半日內潮的贡献则相对较弱。进一步分析发现,冬季中尺度暖涡能够极大地增强海洋上层的亚惯性剪切;夏、秋季南海活跃的台风所激发的近惯性内波能够造成近惯性剪切增强。另外,研究还发现,背景涡度对近惯性剪切具有重要的调制作用,即负涡度相较于正涡度更有利于近惯性剪切增强。该研究所揭示的流速剪切的时间变化规律及调控机制对改进海洋混合的参数化方案具有重要的参考价值。 Based on high-resolution moored velocity data from April 2011 to March 2012,the temporal variation and evolution rule of finescale velocity shear in the upper ocean of northern South China Sea were investigated.According to the spectrum analysis of the velocity shear,it is found that the velocity shear in the upper ocean of northern South China Sea is mainly controlled by four processes sub-inertial motion,near-inertial internal waves,diurnal tide and semi-diurnal tide.The wind-generated near-inertial internal waves and sub-inertial motion corresponding to mesoscale eddy is the main reason for the temporal variation of shear,while the contribution of the diurnal and semi-diurnal tides emphasized in the past is relatively weak.Further research shows that the warm-core eddy in winter can greatly enhance the sub-inertial shear in the upper ocean.The near-inertial internal waves induced by active typhoons in the South China Sea in summer and autumn strengthen the near-inertial shear.The study also found that the background vorticity has an important modulation effect on the near inertial shear,that is,the negative vorticity is more favourable to the near-inertial shear enhancement than the positive vorticity.The temporal variation characteristics and driving mechanism of velocity shear revealed by this study have important reference value for improving the parameterization of ocean mixing.
作者 商巩 张金超 张志伟 SHANG Gong;ZHANG Jin-Chao;ZHANG Zhi-Wei(College of Oceanic and Atmospheric Scineces;Key Laboratory of Physical Oceanography, Ministry of Education;Institute for Advanced Ocean Study, Ocean University of China, Qingdao 266100, China)
出处 《中国海洋大学学报(自然科学版)》 CAS CSCD 北大核心 2020年第11期12-21,共10页 Periodical of Ocean University of China
基金 中央高校基本科研业务费专项(202041009) 国家自然科学基金项目(41706005) 国家重点研究发展计划项目(2018YFA0605702,2016YFC1402605)资助。
关键词 细尺度流速剪切 南海北部 中尺度涡 近惯性内波 台风 内潮 finescale velocity shear Northern South China Sea mesoscale eddy near-inertial waves typhoons internal tides
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