MOM4_L40模式对全球海洋CFC-11分布的模拟及其通风能力评估

Simulation of CFC-11 distribution based on the global oceanic carbon cycle model MOM4_L40 and assessment of its ventilation capability

CFC-11是评估全球海洋环流模式的一个重要工具,海水中溶解的CFC-11被用来分析全球海洋模式的通风模拟.本文在中国气象局国家气候中心发展的40层全球海洋环流模式(MOM4_L40)增加了示踪物CFC-11模块,然后利用该模式研究了CFC-11在全球海洋中的分布,并评估了模式的通风能力.对CFC-11的海表浓度、柱总含量以及大洋剖面的垂直浓度分布和渗透深度进行了分析,结果表明,与观测相比,模式较好地再现了CFC-11在海洋表面的水平分布特征,CFC-11主要储存区位于西北大西洋、副热带北太平洋及南大洋,其浓度分布与温度分布梯度相反.沿三个大洋的5个剖面的CFC-11垂直分布模拟也与观测基本吻合.模式模拟的CFC-11分布情况与全球平均经向流函数吻合,在南大洋模拟效果更加接近观测值,深海模拟效果较好,渗透深度接近观测.同时,模拟与观测相比也存在偏差.比如在北大西洋主要的存储区域,模式低估了CFC-11的吸收,这与高纬的CFC-11向低纬过度输送有关,可能是受温盐环流和强迫资料的影响.总体来说,MOM_L40模式模拟大洋吸收的CFC-11总量是理想的,通过模拟被动示踪物CFC-11很好地再现了海洋的通风能力.

CFC-11 is an important tool to assess the ocean cycle model,which dissolved inseawater is used to analyze ocean ventilation.In this paper,a tracer CFC-11 module is developed on the basis of a global oceanic carbon cycle circulation model MOM4_L40 developed by National Climate Center of China Meteorological Administration.Then this model is employed to study the distribution of CFC-11 in the global ocean and to assess the model ventilation capacity.The simulated parameters,such as global sea surface CFC-11 concentration,inventory,vertical penetration depth and concentration distribution,are verified against their observations.The results show that the model can reasonably simulate the surface and vertical distribution of CFC-11.The main storage of CFC-11 is located in the Northwest Atlantic,subtropical North Pacific and the Southern Ocean.Distributions of CFC-11 concentrations in the ocean surface are remarkably affected by sea surface temperature.The distribution of simulated CFC-11 agrees well with that of observations,showing an opposite gradient to sea surface temperature.Compared with the observations of five sections in three oceans,the simulation results of CFC-11 are generally in agreement with the observations in most areas.In addition,the distribution of simulated CFC-11 is consistent with meridional overturning circulation in the global ocean,such as better simulation in the Southern Ocean and deep ocean,as well as the penetration depths.However,there are some deviations between the observation and simulation.For example,in the North Atlantic where there is a main storage of CFC-11,our model underestimates the absorption of CFC-11 related to over-transport from high latitudes to low latitudes,which may be influenced by thermohaline circulation and forced data.By and large, MOM_L40 simulates well the absorption of total CFC-11 in the ocean appreciably well,and reproduces the ocean ventilation capability by the simulated CFC-11 with a passive tracer.