基于空间基函数客观拟合的副高突变与多态机理分析

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

为分析研究副热带高压异常活动的动力学机理,基于热力强迫和涡动耗散效应的大气偏微涡度方程,采用Galerkin方法进行方程的时-空变量分离,针对常规方法在空间基函数选择中存在的不足和欠缺,提出了从实际资料场序列中用经验正交函数(EOF)分解与遗传算法结合客观反演空间基函数的研究思想.通过对副热带高压位势场逐日时间序列的EOF分解,选择累积方差贡献超过90%的前3个主要空间典型场作为拟合对象,随后选择一组三角函数簇作为广义空间基函数,以该基函数与EOF典型场的误差最小二乘和基函数间的完备正交性构造双约束泛函,再引入遗传算法进行空间基函数曲面拟合和系数优化,反演得到客观合理的副热带高压常微动力模型.进一步通过历史感热场资料的EOF分解和反演,建立了一个客观考虑了热力因子分布的副热带高压常微动力学模型.最后,基于获得的非线性动力学模型,对热力强迫作用下的副热带高压的复杂动力学行为和突变机理进行了分析和讨论,得到了一些新的见解.如东亚副热带地区东-西向感热强度和结构分布以及东-西向热力差异,可能是导致副高流场和位势场出现多元复杂形态(包括副高双脊线现象)的诱因;太阳辐射感热效应和东亚大陆东-西向感热结构与热力差异的不同组合的共同作用,则可能是导致副高增强和西伸、北跳等突变的重要因素。

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 eastwest 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.