Lidar Observation Of Vertical Transoport Induced By Gravity Wave In The Mesopause Region

The mesopause region(85-100 km)is an important region for the exchange of momentum,heat and atmospheric chemical compositions between the lower atmosphere and the upper atmosphere,and is also an important region where the neutral atmosphere and the ionospheric atmosphere are coupling.Studying the vertical dynamical transport mechanisms has great significant value to understand the above process in the mesopause.This article focuses on the contribution of the vertical perturbations and transport mechanism induced by atmospheric gravity wave.Observation data derived from the LangFang station of National Space Science Center,Chinese Academy of Science,with a Na fluorescence Doppler lidar and a meteor radar,were used to study the characteristic of vertical wind perturbations,vertical heat transport,vertical Na transport which induced by gravity wave in the mesopause region.The results can provide observation references for the parameterization scheme of atmospheric model and study of the near space.Specific research contents have the following aspects:1,Original observation data of lidar and meteor radar are first put through to the quality control process.The method of perturbations extraction is computed by subtracting the linear trend in time(each night of observation)at each altitude as the instantaneous perturbations induced by atmospheric gravity wave.The results show that the temperature,the three-dimensional wind and the density of sodium atoms perturbations are well consistent with the Gaussian distribution of zero mean,which proves the observation data are reliable.Data preprocessing makes the basis for the following relevant research work.2,According to the scale analysis condition,the quantitative classification standards of high,medium and low frequency gravity waves are firstly established,then,according to the polarization and dispersion relation of quasi-monochromatic gravity wave to simulate the vertical wind perturbations.The result shows vertical wind perturbations induced by high frequency gravity wave and medium frequency gravity wave can reach 1~10 m/s.The simulations indicate the quasi-monochromatic gravity waves are capable of producing vertical wind perturbations with the velocity of 10 m/s.This study can provide the supports for measurements of vertical wind,vertical wind simulation and gravity wave parameterization.3,Temperature and vertical wind profile data of Na lidar were used to study the characteristic of atmospheric temperature structure,stability,mean vertical heat flux and mean dynamical cooling rate which induced by gravity wave dissipation in the mesopause region.The temperature was in the lowest area from 92 to 96 km,where the buoyance frequency N2 was also in the lower area,the mean vertical heat flux induced by gravity wave dissipation was obviously downward and produced a net dynamical cooling effect to background atmosphere,it was considered to make a contribution to the lowest atmospheric temperature and play an important role of thermal balance.4,Vertical wind and sodium atoms density profile data of Na lidar,were used to study the effect of Na atoms vertical transport induced by gravity wave dissipation in the mesopause region.The mean vertical Na flux was mostly downward from 90 to 100 km and upward from 85 to 89 km,those results suggest the effect of gravity wave dissipation make Na atoms gathered at near 91 km and make the mean Na production rate significantly increase.It indicates gravity wave dissipations play an important role in the formation of Na layer structure and peak value in the mesopause region.5,Sodium atoms density,vertical wind and temperature data derived from a Na lidar,were used to study the gravity wave-induced dynamical transport,chemical transport and turbulence mixing transport of Na atoms;Meridional wind data derived from a Meteor radar were used to characterize the advection transport in the mesopause region.The results showed that four dynamical transport mechanisms of sodium atoms were roughly comparable at 85~100 km,but the different transport mechanism has the different status with altitude increasing.The four dynamical transport mechanisms produce a combined average velocity of-1 cm/s between 88 and 95 km,downward dynamical transport mechanisms play a very important role to the balance of sodium layer.6,Compare with the observations in SOR and Maui,the magnitude of heat flux,dynamical cooling rate,Na flux and Na production rate induced by gravity wave are comparable between three stations,but there are some differences in the mean profiles,the peak value and its heights of those parameters are not the same,the mean profiles also have a different sharp.The geographical factors are considered to make contribution to the diversities of gravity wave activities and vertical transport in different locations.The specific causes of the differences and the characteristics of global variation of Na atoms transport remain to be further researched.