本文选用中国科学院大气物理研究所全球海洋模式（LICOM），对中尺度涡旋参数化方案（GM90方案）中等密度扩散系数和等密度面厚度扩散系数（统称为涡旋扩散系数 Aρ）对物理场及 CFC-11（一氟三氯甲烷）分布的影响进行了研究。本文做了两个试验，即涡旋扩散系数采用常系数方式（对照试验）和采用在非绝热层以下Aρ随海洋浮力频率垂直变化的参数化方案（浮力试验）。模拟结果表明，依浮力频率垂直变化的方案对模式物理场的模拟能力有一定程度的提升，如南极绕极流的输送强度比常系数方案增大了约20%～30%，与观测事实更接近；浮力试验对对照试验中过强的南极中层水有一定的削弱作用，使得模式对南大洋高纬次表层位密度的模拟有一定的改善。稍有不足的是，浮力试验对南极底层水也有一定的削弱，使得2000～3000 m 深度位密度模拟较常系数方案偏低。通过对CFC-11分布、存储以及输送的研究发现，次网格参数取值的不同对南大洋CFC-11模拟情况有较大影响。浮力试验加大了南北高纬CFC-11海表的吸收通量，对南极大陆周边海域向南大洋主储藏区（34°S～60°S）的CFC-11输送能力有一定的增强，使得南大洋对CFC-11储藏量增大，大部分海区与观测资料更接近。通过CFC-11断面分析，浮力试验对南大洋上层海洋位密度模拟的改善使得CFC-11垂直结构与观测更接近。%The global ocean model, LICOM, developed by the Institute of Atmospheric Physics of the Chinese Academy of Sciences, was used to study the influences of both the isopycnal diffusivity and the thickness diffusivity (collectively called eddy diffusion coefficients) in the parameterization of mesoscale tracer transports (GM90 scheme) on the physical fields and CFC-11 distribution characteristics. Two numerical experiments were designed, including a run called CONTROL in which the eddy diffusion coefficients were spatially constant, and the other called BUOYANCY in which the eddy diffusion coefficient (Aρ) varied in the vertical direction along with the ocean buoyancy frequency below the diabatic layer depth. The simulation results showed that the simulation ability of the physical field was improved to a certain degree in the mixing scheme with the buoyancy frequency-dependent eddy diffusion coefficients. For example, compared to the mixing scheme with constant eddy diffusion coefficients (CONTROL), the Antarctic circumpolar current transport strength in BUOYANCY was increased by about 20%–30%, which was closer to the observations. Relatively strong Antarctic Intermediate Water from CONTROL was reduced in BUOYANCY, resulting in improvement of the simulation of subsurface potential density in the high-latitude region of the Southern Ocean. Nevertheless, a deficiency in BUOYANCY was that the strength of Antarctic Bottom Water was weakened, leading to the potential density in the region of 2000–3000 m depth in BUOYANCY being lower than that in CONTROL. Through analysis of the distribution, storage and transport of CFC-11, it was found that the different values of subgrid parameters had a relatively large influence on the simulation of the CFC-11 in the Southern Ocean. Specifically, compared to CONTROL, more CFC-11 was taken up in the high-latitude region, and transported from the region near the Antarctic continent to the Southern Ocean’s main storage area (34°S–60°S), leading to the increase in CFC-11 inventory in the Southern Ocean in BUOYANCY, which was closer to the observations in most areas. In addition, it was found from the analysis of CFC-11 distributions in the given section that a certain improvement of the simulation of potential density in the upper layers of the Southern Ocean in BUOYANCY made the vertical structure of CFC-11 closer to the observation, relative to that in CONTROL.
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