条件非线性最优扰动在热带气旋调控减灾中的应用初探

Preliminary Study on Applying Conditional Nonlinear Optimal Perturbation to Tropical Cyclone Mitigation

为主动减小热带气旋灾害,给将来热带气旋调控的工程实践奠定理论基础。从RossHoffman对热带气旋调控减灾的研究出发,引出了作为非线性最优控制技术的四维变分天气控制版本。简要介绍了条件非线性最优扰动(CNOP)的概念,在此基础上,重点介绍了CNOP方法与四维变分方法相比改进方面的主要应用,它可以利用控制过程中的观测数据,从而在天气控制方面优于四维变分技术。进一步研究了CNOP在热带气旋控制中的另外两个应用,即对初始扰动发展为热带气旋的反演以及利用CNOP寻求产生最大垂直风切变的扰动。新的非线性最优控制技术可称为"非线性最优强迫变分(NOFV)"或"非线性最优强迫扰动(NOFP)"方法,它可以使控制尽可能接近观测。研究表明,CNOP方法在热带气旋调控减灾中大有用武之地。

To initiatively mitigate the tropical cyclone disaster and lay a theoretical basis for engineering practice of tropical cyclone control in the future,investigations into tropical cyclone mitigation,especially those made by Ross Hoffman,were introduced in the beginning to elicit the weather control version of 4-Dimensional Variation(4 D-Var)as a nonlinear optimal control technique and the theory of natural cybernetics.Subsequently,the concept of Conditional Nonlinear Optimal Perturbations(CNOP)was briefly presented.On this basis,the primary application of CNOP,improved by comparison with 4 D-Var,were stressed upon,which can make use of the observational data during the controlling process,thereby having some advantages over 4 D-Var in weather control.Moreover,two other applications of CNOP,i.e.inversion of the initial perturbation evolving into a tropical cyclone and the solution of perturbation yielding maximum vertical wind shear with CNOP,were further investigated.The technique may be called‘nonlinear optimal forcing variation calculus(NOFV)’or‘nonlinear optimal forcing perturbation(NOFP)’approach,which could make controlling as close to the observation as possible.The investigation and analysis show that CNOP approach are useful in tropical cyclone mitigation.