A Comparative Study of CART and PTM for Modelling Water Age

作     者：WANG Haiyan GUO Xinyu LIU Zhe GAO Huiwang 

作者机构：Key Laboratory of Marine Environment and Ecology Ministry of Education Ocean University of China Center for Marine Environmental Studies Ehime University 

出 版 物：《Journal of Ocean University of China》 (中国海洋大学学报（英文版）)

年 卷 期：2015年第14卷第1期

页      面：47-58页

核心收录：

学科分类：07[理学] 0707[理学-海洋科学] 

基　　金：funded by the National Natural Science Foundation of China (Nos. 41176007 and 40706007) 

主　　题：CART PTM pseudo displacement water age 

摘      要：CART(Constituent-oriented age and residence time theory) and PTM(Particle-tracking method) are two widely used numerical methods to calculate water age. These two methods are essentially equivalent in theory but their results may be different in practice. The difference of the two methods was evaluated by applying them to calculate water age in an idealized one-dimensional domain. The model results by the two methods are consistent with each other in the case with either spatially uniform flow field or spatially uniform diffusion coefficient. If we allow the spatial variation in horizontal diffusion, a term called pseudo displacement arising from the spatial variation of diffusion coefficient likely plays an important role for the PTM to obtain accurate water age. In particular, if the water particle is released at a place where the diffusion is not the weakest, the water age calculated by the PTM without pseudo displacement is much larger than that by the CART. This suggests that the pseudo displacement cannot be neglected in the PTM to calculate water age in a realistic ocean. As an example, we present its potential importance in the Bohai Sea where the diffusion coefficient varies spatially and greatly.