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 2017-03-10
Abstract：本文选择参数化的电离层热层理论模型TIEGCM作为背景模型，基于COSMIC 掩星观测的电子密度廓线数据，应用集合卡尔曼滤波方法建立了全球电离层电子密度同化模型，实现了全球电离层的电子密度同化。同化结果表明，该同化模型能将观测资料有效地同化到背景模式中，获得全球三维电离层电子密度。与背景模式相比，同化得到的电子密度相对于观测值的偏差显著下降。此外，分组同化与同时同化的结果对比显示，平均偏差改善基本一致，同时同化后的标准偏差在峰值高度以上略有减小。
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2017-01-22
Abstract： Wind and temperature data detected by the first meteorological rocket of the Meridian Space Weather Monitoring Project was used tostudy quasi-monochromatic inertia gravity waves over Hainan rocket launch site(19.5°N,109°E).The GW extracted from the stratosphere (troposphere)revealed by rocketsonde is upward(downward) GW,both propagate against the background wind.The intrinsic period, vertical wavelength ，horizontal wavelength ，vertical group velocity ,and horizontal group velocity of Stratospheric(Tropospheric)GWare 20.1 h(22.4 h),9.5 km(4 km), 2900 km(753 km) ,0.0887（0.0298）m/s,and12.7（3.65）m/srespectively. There is a significant difference between and because of the background wind. The ratio and is 305:1(188:1) and 143:1(122:1) for the stratospheric(tropospheric) GW, the former is about 1.62(1.17) times of the latter.
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 2017-01-22
Abstract： This study use the wind data from the observation of China Langfang (39°N，117°E) meteor radar during the 1 April 2012 to 31 March 2013 to investigate the features of the mesospheric and lower thermospheric mean winds within 80-100 km altitude regions. The results show that the mean zonal winds and mean meridional winds both have obviously seasonal variations. During the winter, eastward winds prevail in the MLT ranges, which is strong in mesosphere and decrease versus increasing altitude. In the summer, westward winds dominate in mesosphere, and decrease along with increasing altitude, then turn to the strong eastward in lower thermosphere. The wind evolution in the spring and autumn are the transition characters between the summer and winter. The mean meridional winds are southward in summer and northward with sometimes reversal in winter, in general. The above main seasonal variations of mean winds are captured largely by the simulation of WACCM4 model and HWM93 model. WACCM overestimates the winds, but HWM93 underestimates the winds.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2017-01-22
Abstract： Parameterized ionosphere model TIEGCM is used as background model. Basing on the COSMIC observations, global ionospheric electron density assimilation model is established using ensemble Kalman filter. Result shows, this model can effectively assimilate observations into background model and acquire three dimensional ionospheric electron density. Compared to background, the error between analysis and observations decreases significantly. The root mean square error(RMSE) of NmF2 decreases about 60% for observations assimilated, and 20% for observations not assimilated. The RMSE of hmF2 doesn’t get improvement except for mean error. The results of simultaneous assimilation (SA) and batches assimilation (BA) are compared for this case. The time that the two methods spend in assimilation is about 6 to 7 minutes, which does not differ very much. SA needs nearly 8 GB storage while BA less than 2GB. The statistic of electron density error shows that they nearly acquire the same mean error, but the SA gets relative better improvement in RMSE above 250km.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-13
Abstract：利用全天时钠层荧光激光雷达和GPS电离层探测仪, 在2009年7月22日武汉日全食期间, 开展钠层与电离层的联合观测试验. 观测结果表明, 钠层密度半高全宽在日全食过程中稍有变窄, 而日全食过后增宽, 钠层峰值高度在日全食过程中稍有降低, 日全食过后高度略增, 钠层变化特性表现出快速的日出日落过程. 电离层电子总含量和天空背景光噪声也随日全食期间太阳辐照的变化而呈现出明显下降和上升的波动特征. 所不同的是, 钠层原子的这种半宽度起伏变化要比电离层的变化迟缓得多, 这可能是由于钠层受到日全食辐照扰动后, 会产生一系列复杂的光化学反应及动力输运过程, 再复合成钠原子被激光雷达探测到, 有一个滞后过程, 这也正好与理论模拟的结果相符.
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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