Subjects: Geosciences >> Space Physics submitted time 2017-03-10
Abstract：利用廊坊站(40.0° N，116.3° E)钠层测温测风激光雷达2011年至2013年共约82h的钠原子数密度和垂直风观测数据，首次分析了廊坊地区中间层顶区域大气重力波耗散引起的钠原子输送作用. 分析得到，90~100 km重力波耗散引起的平均钠原子垂直通量整体为负，钠原子向下输送，在93 km处出现最大负值为-1.47×108 m-3 m/s，85~90 km平均钠原子垂直通量为正，钠原子向上输送，但通量值随高度递减. 钠原子垂直通量方向在90 km处发生转变. 垂直通量随高度的变化造成钠原子汇聚，汇聚效应引起的平均钠原子产生率最大值在91km处达到了1.4×108 m-3/h，该值超过了相同高度上理论模拟的流星烧蚀注入引起的钠原子产生率峰值，说明它对钠层结构的形成具有重要的贡献. 分析结果与美国的观测结果相比，平均钠原子产生率峰值大小相近，但出现高度不同，说明大气重力波耗散引起的物质输送具有较大的地域变化特征. 研究结果可为大气物质输送理论的完善以及大气金属层物理模式的改进提供观测事实参考.
Peer Review Status:
Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2017-01-22
Abstract： By studying Rayleigh lidar data，The seasonal variations of atmospheric temperature of 35-70km in Beijing area are analyzed.The atmospheric temperature between 30-70km height range at Beijing region has obvious annual cycle variation. The highest temperature in the stratosphere appeared in June and July, which is about 270K. The lowest temperature in the middle layer 70km is also in June, July, about 200K. Take the data of October 14, 2014 as an example， Gravity wave dissipation under 50km is found，while， the gravity waves propagate upward almost without dissipation above 50km.By comparing the average potential energy density between 35-50km height range, the seasonal variation of the gravity waves activities intensity in the Beijing area was studied. The gravity waves activities over Beijing have an obvious cycle of one year.The average potential energy density in winter is , while in summer, the average potential energy density is , the gravity waves activities intensity in winter is about two times of that in summer. In addition, the profile of seasonal averaged gravity waves potential energy density are given in spring,summer,autumn and winter. The dissipation of gravity waves in different seasons and different heights is analyzed in Beijing area.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-13
Abstract： The spaceborne sodium Doppler lidar can be developed to measure global wind, temperature and sodium number density in the mesopause and lower thermosphere region. In order to analyze the feasibility of the lidar, simulation calculations about backscattering signals and measurement accuracy have been done in this paper. The analyzed result shows that the line-of-sight wind accuracy, horizontal wind accuracy and temperature accuracy are 0.8 m/s, 1.5 m/s and 2.5 K when the height of satellite orbit is 400 km, observational angle is 30.0� laser power is 9.0 W, receiver diameter is 1.0 m, vertical range resolution is 2.0 km, and signal integrated time is 30.0 s.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-03
Abstract： Gravity wave activity in the upper stratosphere is investigated using density data retrieved from the Rayleigh lidar of National Space Science Center, Chinese Academy of Sciences. Combining the Rayleigh lidar data with the wind data of National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS), we study a mountain wave observed on November 11, 2013. The parameters of this mountain wave, such as propagation direction and propagation speed, have been calculated. Gravity wave perturbations are extracted from 0.5 h×1 km density profiles. The relative density perturbations are expressed by ρ'(z)=(ρ(z)-ρ0(z))/ρ0(z), where ρ(z) is the measured atmosphere density, and ρ0(z) is the background density which is calculated by fitting the logarithmic form of whole night mean density with 4 order polynomial. The background wind data are achieved by applying a linear polynomial fitting to the NCEP-GFS wind data between 20 to 48 km altitude. Using the data extracted from the complete density perturbations structure and the background wind data, we calculate the parameters of gravity waves observed on November 11, 2013 by the gravity wave dispersion equation. The complete density perturbation structure shows an obvious phenomenon of mountain gravity wave activity. The wave phases at same altitude remain unchanged in the whole night. The perturbation structure shows that vertical wavelength is about 5.5 km but changes with altitude. A group of over-determined equations can be established by substituting the data extracted from the complete density perturbations structure and the background wind data into the gravity wave dispersion equation. And two groups of solutions are obtained by using the least squares method to solve these over-determined equations. The wind profiles in the direction of two sets of solutions have been analyzed. A critical layer (zero wind layer) which will prevent the upward propagation of mounting waves is found in the wind profile in the direction of 37.9°(or 217.9°). Finally, the gravity waves observed on November 11, 2013 propagate in the direction of 52.4° from the north to the west, with a horizontal wavelength of 5.5 km. Compared with inertia waves, there is no downward-propagating or upward-propagating phase in the density perturbation structure. At the same altitude, the phase remains unchanged in the whole night. Such kind of gravity wave perturbation structures have been often observed in winter. Density data obtained by Rayleigh lidar and NCEP-GFS wind data at Beijing are used to analyze a mountain wave parameters observed on November 11, 2013. By analysis, we obtain terrain-generated gravity waves propagating in the direction of 52.4° from the north to the west, with a horizontal wavelength of 5.5 km and average vertical wavelength of 6.0 km. ©, 2015, Science Press. All right reserved.
Peer Review Status:Awaiting Review
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