The atmospheric temperatures and densities in the mesosphere and lower thermosphere(MLT)region are essential for studying the dynamics and climate of the middle and upper atmosphere.In this study,we present more than ...The atmospheric temperatures and densities in the mesosphere and lower thermosphere(MLT)region are essential for studying the dynamics and climate of the middle and upper atmosphere.In this study,we present more than 9 years of mesopause temperatures and relative densities estimated by using ambipolar diffusion coefficient measurements observed by the Mengcheng meteor radar(33.4°N,116.5°E).The intercomparison between the meteor radar and Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Sounding of the Atmosphere by Broadband Emission Radiometry(TIMED/SABER)and Earth Observing System(EOS)Aura/Microwave Limb Sounder(MLS)observations indicates that the meteor radar temperatures and densities agree well with the simultaneous satellite measurements.Annual variations dominate the mesopause temperatures,with the maximum during winter and the minimum during summer.The mesopause relative densities also show annual variations,with strong maxima near the spring equinox and weak maxima before the winter solstice,and with a minimum during summer.In addition,the mesopause density exhibits a structure similar to that of the zonal wind:as the zonal wind flows eastward(westward),the mesopause density decreases(increases).At the same time,the meridional wind shows a structure similar to that of the mesopause temperature:as the meridional wind shows northward(southward)enhancements,the mesopause temperature increases(decreases).Simultaneous horizontal wind,temperature,and density observations provide multiple mesospheric parameters for investigating mesospheric dynamics and thermodynamic processes and have the potential to improve widely used empirical atmospheric models.展开更多
Observations of a quasi-90-day oscillation in the mesosphere and lower thermosphere(MLT) region from April 2011 to December 2014 are presented in this study. There is clear evidence of a quasi-90-day oscillation in te...Observations of a quasi-90-day oscillation in the mesosphere and lower thermosphere(MLT) region from April 2011 to December 2014 are presented in this study. There is clear evidence of a quasi-90-day oscillation in temperatures obtained from the Kunming meteor radar(25.6°N, 103.8°E) and Sounding of the Atmosphere using Broadband Emission Radiometry(SABER), as well as in wind observed by the Kunming meteor radar. The quasi-90-day oscillation appears to be a prominent feature in the temperatures and meridional wind tides and presents quite regular cycles that occur approximately twice per year. The amplitudes and phases of the quasi-90-day oscillation in the SABER temperature show a feature similar to that of upward-propagated diurnal tides, which have a vertical wavelength of ～20 km above 70 km. In the lower atmosphere, a similar 90-day variability is presented in the surface latent heat flux and correlates with the temperature in the MLT region. Similar to the quasi-90-day oscillation in temperature, a 90-day variability of ozone(O3) is also present in the MLT region and is considered to be driven by a similar variability in the upwardly-propagated diurnal tides generated in the lower atmosphere. Moreover, the 90-day variability in the absorption of ultraviolet(UV) radiation by daytime O3 in the MLT region is an in situ source of the quasi-90-day oscillation in the MLT temperature.展开更多
By using atmospheric wind data in the mesopause and lower thermosphere(MLT)region,features of seasonal variations in the quasi-6-day wave(6DW)at different latitudes are analyzed,and modulation of the 6DW by the diurna...By using atmospheric wind data in the mesopause and lower thermosphere(MLT)region,features of seasonal variations in the quasi-6-day wave(6DW)at different latitudes are analyzed,and modulation of the 6DW by the diurnal tide and solar 27-day period is discussed.The data used in the analysis are extracted from a wind dataset collected by a meteor radar chain from December 2008 to November 2017.The meteor radar chain includes four stations,in Mohe,Beijing,Wuhan,and Sanya.Features of seasonal variations in the 6DW indicate that in summer the 6DW is usually strongest during July and August,followed by stronger variations in January and April.At certain altitudes over Wuhan and Sanya,the 6DW is slightly different in different years and altitudes.In our analysis of seasonal variations in the 6DW,we find that it is generally affected by annual oscillations and semiannual oscillations.The annual oscillations of the 6DW in the mid-low latitudes are modulated by the quasibiennial oscillation in the diurnal tide,resulting in seasonal features that are different from those at other latitudes.In addition,the 6DW amplitude at mid-high latitudes has a significant 27-day solar rotation variation,which was prominent in 2016.展开更多
A meteor radar chain located along the 120°E meridian in the Northern Hemisphere from low to middle latitudes provides longterm horizontal wind observations of the mesosphere and lower thermosphere(MLT)region.In ...A meteor radar chain located along the 120°E meridian in the Northern Hemisphere from low to middle latitudes provides longterm horizontal wind observations of the mesosphere and lower thermosphere(MLT)region.In this study,we report a seasonal variation and its latitudinal feature in the horizontal mean wind in the MLT region observed by six meteor radar instruments located at Mohe(53.5°N,122.3°E),Beijing(40.3°N,116.2°E),Mengcheng(33.4°N,116.5°E),Wuhan(30.6°N,114.4°E),Kunming(25.6°N,108.3°E),and Fuke(19.5°N,109.1°E)stations.In addition,we compare the wind in the MLT region measured by the meteor radar stations with those simulated by the Whole Atmosphere Community Climate Model(WACCM).In general,the WACCM appears to capture well the seasonal and latitudinal variations in the zonal wind component.In particular,the temporal evolution of the eastward zonal wind maximum shifts from July to May as the latitude decreases.However,the simulated WACCM meridional wind exhibits differences from the meteor radar observations.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 42125402 and 42174183)the National Key Technologies R&D Program of China (Grant No. 2022YFF0503703)+5 种基金the B-type Strategic Priority Program of the Chinese Academy of Sciences (Grant No. XDB41000000)the foundation of the National Key Laboratory of Electromagnetic Environmentthe Fundamental Research Funds for the Central Universitiesthe Chinese Meridian Projectfunded by the Anhui Provincial Natural Science Foundation (Grant No. 2008085MD113)the Joint Open Fund of Mengcheng National Geophysical Observatory (No. MENGO-202209)
文摘The atmospheric temperatures and densities in the mesosphere and lower thermosphere(MLT)region are essential for studying the dynamics and climate of the middle and upper atmosphere.In this study,we present more than 9 years of mesopause temperatures and relative densities estimated by using ambipolar diffusion coefficient measurements observed by the Mengcheng meteor radar(33.4°N,116.5°E).The intercomparison between the meteor radar and Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Sounding of the Atmosphere by Broadband Emission Radiometry(TIMED/SABER)and Earth Observing System(EOS)Aura/Microwave Limb Sounder(MLS)observations indicates that the meteor radar temperatures and densities agree well with the simultaneous satellite measurements.Annual variations dominate the mesopause temperatures,with the maximum during winter and the minimum during summer.The mesopause relative densities also show annual variations,with strong maxima near the spring equinox and weak maxima before the winter solstice,and with a minimum during summer.In addition,the mesopause density exhibits a structure similar to that of the zonal wind:as the zonal wind flows eastward(westward),the mesopause density decreases(increases).At the same time,the meridional wind shows a structure similar to that of the mesopause temperature:as the meridional wind shows northward(southward)enhancements,the mesopause temperature increases(decreases).Simultaneous horizontal wind,temperature,and density observations provide multiple mesospheric parameters for investigating mesospheric dynamics and thermodynamic processes and have the potential to improve widely used empirical atmospheric models.
基金supported by the USTC Research Funds of the Double First-Class Initiative(YD3420002004)the National Natural Science Foundation of China(42125402,41974174,42188101,41831071,42174183,and 41904135)+4 种基金the B-type Strategic Priority Program of CAS(XDB41000000)the Project of Stable Support for Youth Team in Basic Research Field,CAS(YSBR-018)the Fundamental Research Funds for the Central Universitiesthe Anhui Provincial Natural Science Foundation(2008085MD113)the Joint Open Fund of Mengcheng National Geophysical Observatory(MENGO202209).
基金supported by Project(KJCX2-EW-J01,KZZD-EW-0101)of the Chinese Academy of Sciencesthe National Natural Science Foundation of China(41322029,41474129,41421063 and41804147)+5 种基金the National Basic Research Program of China(2012CB825605)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2011324)the Fundamental Research Funds for the Central Universitiesthe open research project of Chinese Academy of Sciences Large Research Infrastructuresthe Chinese Meridian Projectthe Open Research Program of National Key Laboratory of Electromagnetic Environment of the China Research Institute of Radiowave Propagation
文摘Observations of a quasi-90-day oscillation in the mesosphere and lower thermosphere(MLT) region from April 2011 to December 2014 are presented in this study. There is clear evidence of a quasi-90-day oscillation in temperatures obtained from the Kunming meteor radar(25.6°N, 103.8°E) and Sounding of the Atmosphere using Broadband Emission Radiometry(SABER), as well as in wind observed by the Kunming meteor radar. The quasi-90-day oscillation appears to be a prominent feature in the temperatures and meridional wind tides and presents quite regular cycles that occur approximately twice per year. The amplitudes and phases of the quasi-90-day oscillation in the SABER temperature show a feature similar to that of upward-propagated diurnal tides, which have a vertical wavelength of ～20 km above 70 km. In the lower atmosphere, a similar 90-day variability is presented in the surface latent heat flux and correlates with the temperature in the MLT region. Similar to the quasi-90-day oscillation in temperature, a 90-day variability of ozone(O3) is also present in the MLT region and is considered to be driven by a similar variability in the upwardly-propagated diurnal tides generated in the lower atmosphere. Moreover, the 90-day variability in the absorption of ultraviolet(UV) radiation by daytime O3 in the MLT region is an in situ source of the quasi-90-day oscillation in the MLT temperature.
基金the National Natural Science Foundation of China(41774158,41974174,41674150,41831071 and 41904135)the Open Research Project of Large Research Infrastructures of CAS—“Study on the interaction between low/mid-latitude atmosphere and ionosphere based on the Chinese Meridian Project”.
文摘By using atmospheric wind data in the mesopause and lower thermosphere(MLT)region,features of seasonal variations in the quasi-6-day wave(6DW)at different latitudes are analyzed,and modulation of the 6DW by the diurnal tide and solar 27-day period is discussed.The data used in the analysis are extracted from a wind dataset collected by a meteor radar chain from December 2008 to November 2017.The meteor radar chain includes four stations,in Mohe,Beijing,Wuhan,and Sanya.Features of seasonal variations in the 6DW indicate that in summer the 6DW is usually strongest during July and August,followed by stronger variations in January and April.At certain altitudes over Wuhan and Sanya,the 6DW is slightly different in different years and altitudes.In our analysis of seasonal variations in the 6DW,we find that it is generally affected by annual oscillations and semiannual oscillations.The annual oscillations of the 6DW in the mid-low latitudes are modulated by the quasibiennial oscillation in the diurnal tide,resulting in seasonal features that are different from those at other latitudes.In addition,the 6DW amplitude at mid-high latitudes has a significant 27-day solar rotation variation,which was prominent in 2016.
基金supported by the National Natural Science Founda-tion of China(Grant Nos.42125402,41974174,42074181,42188101,41831071,42174183,and 41904135)the B-type Strate-gic Priority Program of the Chinese Academy of Sciences(CAS,Grant No.XDB41000000)+4 种基金the Project of Stable Support for Youth Team in Basic Research Field,CAS(Grant No.YSBR-018)the Open Research Project of Large Research Infrastructures of CAS,titled“Study on the Interaction Between Low/Mid-Latitude Atmosphere and Ionosphere Based on the Chinese Meridian Project,”the Fundamental Research Funds for the Central Universities(Grant No.YD3420002004)the Anhui Provincial Natural Science Foun-dation(Grant No.2008085MD113)the Joint Open Fund of Mengcheng National Geophysical Observatory(MENGO-202209)the foundation of the National Key Laboratory of Electromag-netic Environment(Grant No.JCKY2020210C614240301).
文摘A meteor radar chain located along the 120°E meridian in the Northern Hemisphere from low to middle latitudes provides longterm horizontal wind observations of the mesosphere and lower thermosphere(MLT)region.In this study,we report a seasonal variation and its latitudinal feature in the horizontal mean wind in the MLT region observed by six meteor radar instruments located at Mohe(53.5°N,122.3°E),Beijing(40.3°N,116.2°E),Mengcheng(33.4°N,116.5°E),Wuhan(30.6°N,114.4°E),Kunming(25.6°N,108.3°E),and Fuke(19.5°N,109.1°E)stations.In addition,we compare the wind in the MLT region measured by the meteor radar stations with those simulated by the Whole Atmosphere Community Climate Model(WACCM).In general,the WACCM appears to capture well the seasonal and latitudinal variations in the zonal wind component.In particular,the temporal evolution of the eastward zonal wind maximum shifts from July to May as the latitude decreases.However,the simulated WACCM meridional wind exhibits differences from the meteor radar observations.
