Propagation Characteristics Of Gravity Waves Excited By Deep Convection In Troposphere,stratosphere And Mesosphere

Atmospheric gravity waves generated by excitation sources play a key role in global or regional meteorology,climatology,chemistry,and the dynamics and model parameterization of middle and upper atmosphere and lower atmosphere.In order to analyze the propagation characteristics of gravity waves in stratosphere and mesosphere excited by strong convection like hurricanes,the mechanism of gravity wave upword propagation and the regulation of background wind field are also discussed.In this paper,the research progress of atmospheric gravity wave using multi-sensor satellite data and numerical model is reviewed.On the whole,satellite data plays an important role in the study of the middle and upper atmosphere.It combines with other data to analyze the scale of wave excited by different wave sources,in the climate process,the interaction between wave and wave,the interaction between wave and current,and the significant dynamic coupling mechanism of wave between the troposphere and the whole middle and upper atmosphere.(1)In this paper,we analyzed concentric gravity waves(CGW)detected simultaneously by AIRS(the Atmospheric Infrared Sounder)and VIIRS/DNB(the Day/Night Band of the Visible/Infrared Imager/Radiometer)in the stratosphere and mesosphere.Results show that the gravity waves are generated by the collocated hurricane Bejisa in the island of Mauritius.The AIRS data show gravity waves with horizontal wavelengths of 190/150 km at 21:08 UTC on 1 January and 10:00 UTC on 2 January,and the propagation direction is in the southeast.The DNB observes gravity wave with horizontal wavelengths of 60/150 km at the same geographic regions at 22:24 UTC on 1 January,and the propagation direction was in the southeast and northeast.In addition,the fluctuation center of the stratospheric and mesospheric gravity wave is approximate to the hurricane center.(2)The background wind field has a certain influence on the propagation characteristics of gravity waves using the dispersion relation and Doppler-shifted theory.The parameter characteristics of CGW in the stratosphere(? 40 km)and the mesosphere(? 87 km),such as the vertical wavelength,intrinsic frequency and intrinsic horizontal phase speed,are derived firstly together with the background winds from ERA5 and HWM wind data through the dispersion relation of gravity waves and the wind filtering theory.Background wind were used to construct the blocking diagrams,whichshow the directions and apparent phase speed of wave propagation blocked at a given altitude in the stratosphere and mesosphere,respecvtively.The blocking diagram was then compared with AIRS and VIIRS/DNB observations of gravity waves to better explain the critical layer theory.(3)The tropopause has a certain influence on the propagation of gravity waves during the occurrence and development of Hurricane Bejisa.Using ERA5 data to analyze the height of the tropopause fluctuates between 8?13km.The effect of the tropospheric inversion layer(TIL)on wave propagation was studied through buoyancy frequency.The results showed that the tropospheric inversion layer was weak during January 1st to 6th,2014,corresponding to a small hydrostatic reflection coefficient,and most gravity waves propagated upward.It demonstrates that there is a vertical coupling between the lower atmosphere and the middle atmosphere during convection.