Use High-resolution Radiosonde Data To Calculate The Temporal And Spatial Distribution Characteristics Of Gravity Waves In China

This study uses the high-resolution sounding data of 120 stations in China from June 2014 to Sep 2017 to analyze the statistical characteristics of gravity waves in China.In this research,the latest data processing methods were selected and improved,and various quality control schemes were also formulated in the parameter calculation to obtain more accurate gravity wave parameters(wave energy density,wavelength,intrinsic frequency and propagation direction).Gravity wave in the atmosphere is divided into troposphere(2-10km)and stratosphere(18-25km)to study.The geographical environment,latitude difference and background atmosphere are combined to analysis,and the interference of noise on statistical gravity wave is considered.By this way can make us understand the spatial and temporal distribution of gravity waves and various statistical characteristics of Chinese gravity waves more clearly.The results show:1)There are obvious seasonal changes at all heights of gravity wave energy,which is characterized by strong in winter and weak in summer;in the annual change,the troposphere is characterized by strong and weak years alternation,while the energy of the lower stratosphere is not obvious;about the latitudinal distribution,there is a tendency for the gravity wave energy to decrease when the latitude increases;and about the topographic distribution,the gravity wave energy is larger in areas where there is a strong weather system.2)The vertical wavelength of gravity wave is distributed between 2-3km in the troposphere and lower stratosphere.There is no obvious seasonal variation and annual variation in the troposphere.However,in the geographical distribution,there is a low-value area in the plateau region for a long time.The stratosphere has no obvious annual changes,but in the seasons it is more strongly distributed in summer and autumn,but relatively weak in spring and winter.For the meridional distribution,the vertical wavelength of the troposphere decreases with increasing latitude,and the lower stratosphere increases with increasing latitude,respectively.For the horizontal wavelength of gravity waves,the troposphere and the lower stratosphere are distributed at 100-500 km and 350-1150 km,respectively,with no obvious seasonal and annual changes,while there is a long-term low-value area in the plateau region of the troposphere.In addition,for the meridional distribution,the horizontal wavelength decreases as the latitude increases.In the topographic distribution,the gravity wave vertical wavelength in the troposphere plateau areas is large except for the Qinghai-Tibet Plateau while the lower stratosphere is the opposite,the vertical wavelength showing a low value.3)The intrinsic frequency of the gravity wave is expressed by the ratio of major axis to minor axis of polarization ellipse.The bandpass filtering is performed before the calculation to reduce the error caused by the noise.The intrinsic frequency is distributed in the troposphere at 2-3f and the lower stratosphere at 2-2.5f,respectively(f represents the Coriolis force parameter).There are no obvious seasonal and annual changes,but for geographical distribution,there is a long-term large-value area in the plateau region of the troposphere,and a large-value area in the southwestern part of the lower stratosphere.In the meridional distribution,the ratio increases as the latitude increases.4)The direction of gravity wave propagation is divided into vertical propagation direction and horizontal propagation direction.There is no obvious seasonal variation and annual variation in vertical propagation.The average of the upload rate in the troposphere and lower stratosphere is 50% and 90%,respectively.In the meridional distribution,the gravity wave upload rate of the troposphere increases with the increase of latitude,while the latitude of the lower stratosphere is basically unchanged.For the horizontal direction of gravity wave,it has strong isotropy in the troposphere.As the latitude decreases,the isotropic trend of horizontal propagation decreases.In the lower stratosphere,all regions in the country show strong anisotropy.And these laws do not change with time.