An ocean largeheddy simulation model with application to deep convection in the Greenland Sea
An ocean largeheddy simulation model with application to deep convection in the Greenland Sea
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DOI：
10.1029/95jc02828
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发表时间：
1996-01
影响因子：
--
通讯作者：
D. Denbo;E. Skyllingstad
中科院分区：
文献类型：
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作者：
D. Denbo;E. Skyllingstad
建立了一种非流体静力学的Boussinesq三维模型——海洋大涡模拟模型lOLEMr，用于研究深海对流。该模型采用为大涡模拟模型开发的亚网格尺度湍流参数化，标量的平流采用单调格式完成。利用OLEM进行了一组实验，与实验室结果和大气对流边界层的飞机测量结果进行了直接比较。这些实验结果与室内和大气对流边界层测量的纬向和垂直速度变化、位温变化和热通量的平均剖面非常吻合。横向和纵向速度的水平波数谱也与实验室测量和柯尔莫哥洛夫理论惯性子范围谱符合得很好。利用格陵兰海中部的位温-盐度剖面进行模式初始化实验，研究了温压不稳定和旋转对深海对流结构和演化的影响。人为消除热压不稳定性抑制了穿透性对流，而穿透性对流是造成深度水性质快速变化的原因，这种变化比对流、混合层加深造成的变化要大得多。穿透羽流的垂直速度和直径分别为- 0.08 m s - 1和300 m，与格陵兰海的观测结果吻合较好。一段时间的强穿透对流之后，逐渐过渡到对流，混合层加深。在穿透对流过程中，热通量值约为对流的2倍，混合层加深。在没有旋转的情况下，穿透对流的演化更为迅速，垂直运动更为剧烈。旋转的水平分量的存在迫使穿透羽流周围的环流不对称。这些实验清楚地证明了热压不稳定和旋转对深对流的重要性。为了正确模拟穿透对流区域的大尺度流动，有必要在垂直混合参数化中考虑这些影响。
A nonhydrostatic, Boussinesq, threehdimensional model, the ocean largeheddy simulation model lOLEMr, has been developed to study deep oceanic convection. The model uses a subgridhscale parameterization of turbulence developed for largeheddy simulation models, and the advection of scalars is accomplished using a monotonic scheme. A set of experiments was performed using OLEM to provide a direct comparison with laboratory results and aircraft measurements of the atmospheric convective boundary layer. The results from these experiments are in excellent agreement with laboratory and atmospheric convective boundary layer measurements of the mean profiles of zonal and vertical velocity variance, potential temperature variance, and heat flux. The horizontal wavenumber spectra of zonal and vertical velocity are also in good agreement with laboratory measurements and Kolmogorov's theoretical inertial subrange spectrum. A set of experiments using a potential temperaturehsalinity profile from the central Greenland Sea for model initialization was conducted to study the effect of the thermobaric instability and rotation on the structure and evolution of deep oceanic convection. The artificial removal of the thermobaric instability suppresses penetrative convection, which is responsible for rapid changes in water properties at depths much greater than occurs for convective, mixedhlayer deepening. The vertical velocity and diameter, −0.08 m s−1 and 300 m, respectively, of the penetrative plumes are in good agreement with observations from the Greenland Sea. A period of strong penetrative convection is followed by a gradual transition to convective, mixedhlayer deepening. During penetrative convection, the values of heat flux are about 2 times greater than convective, mixedhlayer deepening. In the absence of rotation, the evolution of penetrative convection occurs more rapidly, and vertical motions are more vigorous. The presence of the horizontal component of rotation forces asymmetries in the circulation around a penetrative plume. These experiments clearly demonstrate the importance of thermobaric instability and rotation on deep convection. To properly model largehscale flows in regions of penetrative convection, it is necessary to include these effects in the vertical mixing parameterization.