吕宋海峡及周边海域湍流混合的时空分布特征研究

利用1992—2002年的温盐深数据与2012—2016年的Argo数据,基于细尺度参数化方法研究了吕宋海峡及周边海域(12°—30°N,115°—129°E)湍流混合的时空分布特征,并分析了地形粗糙度、内潮以及风输入的近惯性能通量对湍流混合的影响。结果表明,吕宋海峡和东海陆坡处具有强混合的特征,扩散率高达4×10~(-3) m~2/s,主要是由内潮产生导致的,其中吕宋海峡主要是M2、K1和O1内潮的贡献,而东海陆坡处主要是M_2内潮的贡献;南海北部也呈现较强的混合,且陆坡处的混合比海盆高1—2个量级;南海中央海盆和离岸的菲律宾海混合较弱,扩散率为O (10-5 m2/s)。此外,在研究区域内,湍流混合的年际变化和季节变化均不明显,且混合扩散率与风输入的近惯性能通量未表现出明显的季节相关。

SPATIAL AND TEMPORAL DISTRIBUTION OF TURBULENT MIXING IN THE LUZON STRAIT AND NEARBY SEA

Based on the fine-scale parameterization method, the spatial and temporal distribution of turbulent mixing in the Luzon Strait and its nearby seas (12°-30°N, 115°-129°E) is presented from the CTD data of 1992-2002 and Argo data of 2012-2016. Furthermore, the effects of topographic roughness, internal tide, and wind-generated near-inertial energy flux on the mixing were analyzed. The mixing of the Luzon Strait and the slope of the East China Sea is strong, and the diapycnal diffusivity is as high as 4×10^-3 m²/s, which is mainly caused by internal tides, especially M₂, K₁, and O₁ internal tides in the Luzon Strait, and M₂ internal tides in the slope of the East China Sea. The northern South China Sea also presents strong mixing, and the diapycnal diffusivity at the slope is about 1-2 orders of magnitude higher than that in the sea basin. However, the mixing between the central basin of the South China Sea and the offshore Philippine Sea is weak, and the diapycnal diffusivity is O (10^-5 m²/s). In addition, the interannual and seasonal variation of turbulent mixing is not obvious in the region, and there is no obvious seasonal correlation between the diapycnal diffusivity and the wind-generated near-inertial energy flux.