全球海洋模式中CFC-11吸收对次网格尺度混合参数化的敏感性
Sensitivity of CFC-11 uptake in a global ocean model to subgrid-scale mixing parameterizations
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摘要: 以描述中尺度涡旋对示踪物的输送作用为目的的湍流混合方案GM90经证明对海洋模式的模拟能力较以前的湍流混合方案有较大的提高.该方案涉及到两个主要参数:等密度面扩散系数(AI)和等密度面厚度扩散系数(Aith).该文的目的就是利用中国科学院大气物理研究所(IAP)全球海洋环流模式L30T63研究以上两个系数取值大小对主动示踪物(温盐)以及被动示踪物(CFC-11)海洋分布的影响.实验结果表明这两个系数的取值可明显改变大洋温盐垂直分布以及海洋对CFC-11的吸收,且两个系数在其中起到的作用有很大的差异.从几个剖面的分析结果可知,总的来说,AI的增加使得CFC-11主要储存区的模拟结果更接近观测资料,而Aith的增大使得模拟结果变差.Abstract: It has been pointed out that a subgrid-scale mixing scheme used in the ocean models for the purpose of describing the transport of tracers by mesoscale eddies,proposed by Gent and McWilliams in 1990,can improve the simulation results,compared with the previous mixing scheme.Two main parameters are involved in the scheme: isopycnal diffusivity (AI) and isopycnalt hickness diffusivity (Aith).In this paper the influence of the two parameters on the distributions of both active and passive tracers is studied with a global ocean general circulation model (L30T63),which is developed by the Institute of Atmospheric Physics of the Chinese Academy of Sciences.A control case and two sensitive cases are designed to study the sensitivity of the uptake and transport of CFC-11 in the ocean to these two parameters.Simulated results show that these two parameters can obviously affect the distribution of temperature and salinity as well as the oceanic uptake of CFC-11.These two parameters play a different role in the transport of both active and passive tracers.It is known from the analysis of CFC-11 distributions at several sections that the increase of isopycnal diffusivity can generally improve the simulated inventory of CFC-11 in the main storage regions whereas the increase of thickness diffusivity makes the simulated result worse.
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