Mechanism analysis of the abnormal activities and polymorphism in subtropical high based on the objective fitting of space-basis function

Abstract

In order to analyze the dynamical mechanism of the abnormal activity of the subtropical high, the variables in the partial differential vortex equations based on the heat force and the whorl movement dissipation effect, are separated in space and time with Galerkin methods. Aiming at resolving the problem of the insufficiency and shortcoming of the conventional method in the choice of space-basis function, we set forth the research idea of using the expirical orthogonal function (EOF) and the genetic algorithm combined with inversion of the space-basis function from the actual sequence of data fields. After the EOF of the daily time series of the subtropical high potential fields, the first three major typical space fields whose cumulative variance contribution is more than 90 percent as the fitting object are chosen, and a group of trigonometric function is selected as the general space-basis function. And then, the dual-constraint function is formulated with the complete orthogonality between space-basis function and the least square of error of general space-basis function and EOF typical field. Then the genetic algorithm is introduced to carry out the curved surface fitting and coefficient optimization of the basis function, and through inversion, an objective and reasonable ordinary differential dynamical model of subtropical high is obtained. Furthermore, through the EOF and inversion of history sensible heat field data, an ordinary differential dynamical model of subtropical high which objectively takes into account of the distribution of thermal factors is set up. Finally, based on the above obtained nonlinear dynamical model, the complicated dynamic behaviors and mechanism of the subtropical high under the impact of heat force are analyzed and discussed, also some new opinions are obtained. For example, the east-west sensitive heat intensity and the configuration distribution and the east-west sensitive heat difference are important factors that lead to a complex configuration (such as the subtropical high double-ridges phenomenon) of the subtropical high flow field and potential field. The heliacal season radicalization heat and the east-west sensitive heat distribution of the East Asia are the important reasons that lead to the subtropical high mutations and the subtropical high flow abnormality, such as the subtropical high north leap and west extend.