| 摘要: |
| 海洋中的跨等密度面湍流混合对于热量和淡水输送、翻转环流以及全球气候变化都有重要影响，理解跨等密度面湍流混合的变化对于改进气候模式模拟和预测大尺度海洋环流的能力具有重要作用。基于细尺度参数化方法，本文利用黑潮延伸体区的一个长期潜标K7观测，对跨等密度面湍流混合的次季节变化进行了分析。结果表明，在2004年6~9月，300~1 350 m的耗散率存在明显的逐月变化，8月份的平均耗散率为2.7×10-9 m2/s3，约为其他月份的2~3倍。跨等密度面湍流混合的这一显著的次季节变化与由风生近惯性内波引起的近惯性剪切的次季节变化密切相关。特别地，在8月中旬，局地风尽管较弱但生成了较强的近惯性内波，在负地转涡度促进下，近惯性内波向下穿透可达1 300 m。能量收支分析显示，8月总的风生近惯性能量是1.7×103 W/m2，其中71%能够进入深海，为跨等密度面湍流耗散提供了52%的能量。该研究为风生近惯性内波在调制深海跨等密度面湍流混合低频变化中的重要作用提供了一个直接依据。 |
| 关键词: 跨等密度面湍流混合 次季节变化 近惯性内波 黑潮延伸体区 |
| DOI：10.11693/hyhz20210700153 |
| 分类号:P731.1 |
| 基金项目:国家重点研发计划，2016YFC0301203号；国家自然科学基金，41606016号，41776021号；中国科学院战略先导专项，XDB42010102号。 |
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| SUBSEASONAL VARIATION OF TURBULENT DIAPYCNAL MIXING IN THE KUROSHIO EXTENSION REGION |
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YAN Xiao-Mei1,2,3, ZHANG Lin-Lin1,2,3, PANG Chong-Guang1,2,3
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1.Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2.Laboratory for Ocean Dynamics and Climate, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China;3.Center for Ocean Mega-Science, Chinese Academy of Sciences, Qindao 266071, China
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| Abstract: |
| Diapycnal mixing in the ocean affects the heat and freshwater transport, overturning circulation as well as global climate changes. Understanding the variability of diapycnal mixing is important for improving the ability of climate models to simulate and predict the large-scale ocean circulations. Based on a finescale parameterization method, the subseasonal variation of turbulent diapycnal mixing in the Kurshio Extension region was analyzed using measurements of a long-term mooring deployed here. During June to September 2004, the inferred diapycnal mixing exhibits significant month-to-month variation. Within 300~1 350 m, the mean dissipation rate in August is 2.7×10-9 m2/s3, which is about 3 times of the value in September. This significant subseasonal variation of the diapycnal mixing is closely related to that of near-inertial shear variance, which is associated with the wind-induced near-inertial internal waves. In particular, in mid-August, the moderate local wind induces strong near-inertial waves that could reach 1 300 m depth. Energy budget analysis indicates that for the total near-inertial wind work of 1.7×10-3 W/m2 in August, about 71% can radiate into the deep ocean and accounts for 52% of the energy required for diapycnal dissipation. Besides, the deep penetration of near-inertial waves is suggested to be facilitated by the negative geostrophic vorticity at that time. This study provides direct evidence for the important role of wind-induced near-inertial waves in modulating low-frequency variation of diapycnal mixing in deep ocean. |
| Key words: turbulent diapycnal mixing subseasonal variation near-inertial internal waves Kuroshio extension region |
