Analysis Of Climatology Of Gravity Wave And Its Influence On “Wave Turbopause” In The Middle And Upper Atmosphere

The middle and upper atmosphere ranges from 10 kilometers above the earth surface to around 300 kilometers,including stratosphere,mesosphere and part of thermosphere.Researches on the middle and upper atmosphere bring us a better understanding of the atmospheric circulation,climate change and so on.The gravity waves,whose amplitudes exponential increase along with the altitude and transfer their momentum and energy to the background atmosphere,are one of the most important dynamical process in the middle and upper atmosphere.Firstly,this study extracts the temperature perturbation profiles based on the 10 years of TIMED/SABER temperature detections and uses the as the strength reference of the gravity waves activity to research its distribution along with latitude and altitude.An analysis of the temporal variation and spectra characteristics associating with atmospheric oscillations is also conducted.Besides,we continue the research on the “wave turbopause” by calculating the higher and lower boundary of“wave turbopause”,the altitude of maximum amplitude due to gravity waves and 6.5day waves respectively and comparing their latitudinal and seasonal variation.This research may help us infer the different roles of different waves in the traditional turbopause regions since the climatology of traditional turbopause and “wave turbopause” are similar and the direct measurements of the former are extremely difficult.Thirdly,the first falling-sphere experiment process and data are analyzed.Most error is attributed to the radar positioning system and the obtained horizontal winds profiles by this experiment and temperature profile from satellite are used to extract gravity waves.The major conclusions in this study are as follows:(1)The distribution of gravity waves activity along with the altitude: there is always a maximum region tending to move to summer hemisphere from 15 to 20 kilometers in the equatorial area and corresponding lower region appears above the maximum region.The gravity waves activity still gains strength although damped by turbulence from 30 kilometers to 80 kilometers around and substantially increase above80 kilometers.As for the seasonal and inter-annual variations,the gravity waves activity is more intense in the winter than in summer no matter for the southern or northern hemisphere.Besides,from 25-degree latitude to 50-degree latitude for both hemisphere,the annual oscillation dominates the gravity waves activity below 80 kilometers but wanes with semi-annual oscillation appears above 80 kilometers.Four-month oscillation is more obvious around the 50 degrees north.Around 30-degree latitude,both the annual and semi-annual oscillation appear below 80 kilometers and the quasi-biennial oscillation arises in the 30 degrees north as well as the four-month oscillation.Around the equator,the annual oscillation exists at lower altitudes and also presents the quasi-biennial oscillation.(2)The latitudinal variation in the “wave turbopause” and the altitude of maximum amplitude of gravity waves are similar.Both of them is lower around the equator and reach the maximum at the mid latitude.However,the seasonal variation in them is anti-correlated.The former is higher in the summer hemisphere while the latter is lower in the northern hemisphere.The analysis shows a lower Brunt-vaisala frequency from85 to 95 kilometers around the 50 degrees north or south,which may result in the increase of amplitude of gravity waves and reaching the maximum amplitude at lower altitude since a lower Brunt-vaisala frequency may lead the growth of the wave amplitude fed by momentum transferred by turbulence.The seasonal variation in the 6.5day waves is consistent with the seasonal variation in the “wave turbopause”,which may imply that different types of atmospheric waves may exert different influences on the “wave turbopause”.(3)The falling-sphere experiment used the radar positioning system and the accuracy of the radar positioning system brings large uncertainty for zonal wind at higher altitude.Satellite positioning system may provide a better measurement in the subsequent research.The vertical wavelength extracted from the zonal,meridional wind and satellite temp profiles by the maximum entropy method concentrate on 4,6.5 and12 kilometers.The vertical wavelength from satellite temp profile solely using S-transform is still around 10?12 kilometers,showing a higher resolution on the falling-sphere measurement.