| In order to reveal the relationship between the activity characteristics of stratospheric gravity waves and tropospheric weather system,a mei-yu rainstorm occurred in the middle and lower reaches of Yangtze River in July 2020 is selected to carry out research.Firstly,based on the diagnostic analysis of reanalysis data and synoptic analysis of rainstorm process,the precipitation evolution characteristics and circulation background are revealed.The mesoscale filtering and spectral analysis of vertical velocity are carried out by Fourier transform method,and the spectral distribution characteristics of gravity waves at different altitudes in the lower stratosphere are revealed,and a complete evolution process of gravity waves in the lower stratosphere in the middle of rain belt is found.Then,based on the theoretical study of the mathematical model,the mathematical model for solving the associated mode of stratosphere and troposphere is given.Under ideal conditions,the analytical solution of the associated mode is obtained.Then,the mode is applied to the complex environment field of the rainstorm,a numerical solution is designed,and the numerical solution is obtained.Innovative conclusions include:1.Reveals the stratosphere of a storm rainfall in the mei-yu gravitational wave evolution process of elimination,finds a gravitational wave equipotential line parallel to the frontal and stretching,the spread of the south(west)to north(east)wave power spectrum asymmetric distribution,and north(east)spread fluctuation of power spectrum is greater than the south(west),this phenomenon becomes more pronounced with height.2.The concept of stratotroposphere associated mode is proposed,and the analytical solution under ideal condition is obtained.For the environmental parameters of the actual rainstorm,a numerical solution is given,which can better reflect the characteristics of stratospheric fluctuation. |
