Study On The Characteristics Of Atmosphere Gravity Waves And Sodium Radiation In The Mesosphere And Lower Thermosphere By Ground-based Optical Observation Over China

Airglow is one of important photochemical reactions in the upper atmosphere.Due to airglow carry important information of photochemistry and dynamics,so it can be considered as an important tracer for studying upper atmosphere.Based on ground-based optical observation,the following three works are carried out:?1?Study on the propagation characteristics of gravity waves by OH all-sky airglow imagers over ChinaIn order to investigate the propagation characteristics of Atmospheric Gravity Waves?AGWs?in China,the first no-gap OH airglow observation network was established in northern China,in February 2012.The network observation,which cover an area of about 2000 km in east and west,and about 1400 km in south and north.The observed period during January 2012 and December 2013.The network observation includes 6 OH airglow imagers,which located at Shuozhou?39.8°N,112.1°E?,Xinglong?40.4°N,117.6°E?,Donggang?40.0°N,124.0°E?,Xinxiang?35.7°N,113.7°E?,Linqu?36.2°N,118.7°E?and Rongcheng?37.3°N,122.5°E?,respectively.The OH airglow imagers located at Fuke?19.5°N,109.1°E?and Guiping?23.4°N,110.1°E?also carried out long-term observation in low-latitude of China.The observation at Fuke from March of 2010 to July of 2012,and at Guiping from September of 2012 to November of 2013.Simultaneously,combining with precipitation data from TAMM satellite,the data of temperature from SABER/TIMED satellite,the measurements of horizontal wind velosity from the ECMWF-MERRA re-analysis,Doppler meteor radar and HWM-07 model,to disscuss the influencing factors of AGWs propagation.The results show in mid-latitude and low latitude,the horizontal wavelengths,observed periods,and horizontal phase speeds of AGWs were typically in the range of 10-35 km,4-12 min,and 30-100m/s,respectively.The propagation directions of AGWs present obvious seasonal variations,over China.In mid-latitude region of China,the AGWs have northwardpropagation preference in summer,and they prefer to equatorward and parallel to the equator propagation in winter.However,in low-latitude,the AGWs show strongly northeastward propagation in summer,and southwestward and southeastward propagation are dominant in winter.Our analyses also suggest that AGWs might mainly caused by convective activity located at south of observed stations in summer.However,the jet streams near tropopause might play a dominant role in determining preferred propagation direction of AGWs in winter.We also find that the filtering effect of background wind from the low and middle atmosphere just be matched well with propagation direction of AGWs in part of seasons.?2?The study of sources of gravity wave events observed by OH airglow imager located at Donggang stationTwo gravity wave events?event 1 and event 2?observed by OH all-sky airglow imager at Donggang?40°N,124°E?station,on the night of 15-16 September 2013.Simultaneously,combining with data of horizontal wind observed by Doppler meteor radar located at Shisanling?40.3°N,116.2°E?,temperature parameters from SABER/TIMED satellite,and a method of reverse ray tracing to study the source regions and propagation environment of these two gravity wave events.The results indicate that the wave source locations of the two events are at 39.3°N,117.2°E?event 1?,and 47.1°N,121.3°E?event 2?,respectively.The wave source location of event 1 is highly related with intensity convective activity and instability caused by up and down motion of the atmosphere.However,event 2 could be caused by convective activity,or the instability due to vertical motion of air masses.In addition,the two events are probably propagate to MLT region from source locations,because the observed phase speeds of 83.5 m/s?event 1?and 80.1 m/s?event 2?are faster than zonal wind velocity?-10-45 m/s?.?3?Study on characteristics of sodium airglow by ground-based optical and SABER/TIMED observationsTo investigate the variable characteristics of relative intensities?R_D?of sodium doublet in the terrestrial nightglow,the ground-based spectrumeter observation of sodium has been taken out at Xinglong?40.2°N,117.4°E?station,during July 2011 and March 2015.The results indicate that R_D lying between 1.2 and 2.2,with an average value of 12.073.1 ±,and they are smaller in summer than in other three seasons.Simultaneously,combining with data sets of sodium density observed by sodium lidar located at Yanqing?40.5°N,116.2°E?,and atmosphere parameters obtained from SABER/TIMED satellite in the range of?40.2 ± 5.0?°N,?117.4 ±5.0?°E,we found that the ratio R_D does not depend on temperature?T?,the mixing ratio of atomic oxygen [O],the ratio of atomic oxygen [O] to molecular oxygen [O₂]?[O]/[O₂]?,the mixing ratio of molecular Ozone [O₃],or density of neutral molecules[M].Due to the seasonal averaged value of peak height of Na density is lower in summer?below 90 km?than in other three seasons?above 91 km?;The seasonal averaged value of peak value of Na density is the maximum in winter,the second in equinoxes,and the lowest in summer;And the seasonal averaged value of R_D is the maximum in winter,the second in equinoxes,and the lowest in summer.Therefore,the results show that the seasonal variation of R_D may be related to the peak height or peak density of Na atoms.In addition,based on modified Chapman mechanism,we assumed R_D=AR_D?A?+XR_D?X?to estimated the ratio of R_D?A?and R_D?x?in total R_D.The results show that A/X?1.0.