共查询到17条相似文献，搜索用时 140 毫秒
1.
本文利用武汉大学的瑞利激光雷达的瑞利散射回波数据(30～65 km)来研究武汉地区上空(305°N，1144°E)〖JP〗重力波的活动规律和统计特性.通过对2003年12月到2005年3月观测的200 h数据反演的密度进行处理分析，得到了重力波的一些个例特征，并提取垂直波长为2 km以上的重力波进行统计分析.结果表明，最可几的垂直波长是3～4 km和17～20 km，重力波振幅的月平均值在冬季有较大值，夏季值较小.与武汉2004年无线电探空仪的密度扰动提取到的重力波做比较，发现与瑞利激光雷达得到的重力波振幅的月平均值有很强的相关性，也是冬季值比较大，夏季值比较小.通过无线电探空仪的风场数据，本文还得到了急流的季节变化规律、最大风剪切年变化规律，发现急流和最大风剪切与激光雷达的重力波统计结果有很强的相关性. 相似文献
2.
本文利用武汉大学的瑞利激光雷达的瑞利散射回波数据(30～65km)来研究武汉地区上空(30.5°N,114.4°E)重力波的活动规律和统计特性.通过对2003年12月到2005年3月观测的200h数据反演的密度进行处理分析,得到了重力波的一些个例特征,并提取垂直波长为2 km以上的重力波进行统计分析.结果表明,最可几的垂直波长是3～4 km和17～20 km,重力波振幅的月平均值在冬季有较大值,夏季值较小.与武汉2004年无线电探空仪的密度扰动提取到的重力波做比较,发现与瑞利激光雷达得到的重力波振幅的月平均值有很强的相关性,也是冬季值比较大,夏季值比较小.通过无线电探空仪的风场数据,本文还得到了急流的季节变化规律、最大风剪切年变化规律,发现急流和最大风剪切与激光雷达的重力波统计结果有很强的相关性. 相似文献
3.
本文利用中国科学院空间科学与应用研究中心的瑞利激光雷达首次观测到了平流层地形重力波活动的现象,并结合美国国家环境预报中心(NCEP)的全球预报系统(GFS)的风场数据分析了该地形重力波的基本参数.与惯性重力波相比较,地形重力波的密度扰动没有下传的相位,在同一高度上,其扰动相位保持不变.北京空间科学与应用研究中心瑞利激光雷达自2012年开始观测实验以来,已经观测到多起地形重力波活动事件.本文以2013年11月11日的观测数据为例,研究北京上空的地形重力波活动,并结合GFS风场数据分析了北京上平流层地形重力波的波长、传播方向、传播速度等参量.通过分析得到在2013年11月11日北京上空存在一列传播方向为北偏西52.4°,水平波长为5.5km,平均垂直波长约为6.0km的地形重力波. 相似文献
4.
为了分析台风这类强对流诱发平流层重力波的过程,本文利用中尺度数值模式WRF-ARW(V3.5)和卫星高光谱红外大气探测器AIRS数据对2011年第9号强热带气旋"梅花"的重力波特征进行了分析.首先,针对模式输出的垂直速度场资料的分析表明,台风在对流层各个方向上几乎都具有诱发重力波的能量,而在平流层内则呈现出只集中于台风中心以东的半圆弧状波动,且重力波到达平流层后其影响的水平范围可达1000km.此外,平流层波动与对流层雨带在形态、位置以及尺度上均具有一定的相似性.其次,对风场的分析结果表明,不同高度上波动形态的差异主要是由于重力波垂直上传的过程中受到了平流层向西传的背景风场以及风切变的调制作用,揭示了重力波逆着背景流垂直上传的特征.随后,基于FFT波谱分析的结果表明,"梅花"诱发的平流层重力波水平波长中心值达到了1000km,周期在15~25h,垂直波长主要在8~12km.最后,利用AIRS观测资料分析了平流层30~40km高度上的大气波动,得到了与数值模拟结果相一致的半圆弧状波动.对比结果也验证了WRF对台风诱发平流层重力波的波动形态、传播方向、不同时刻扰动强度的变化以及影响范围的模拟效果.此外,也揭示了多资料的结合对比有助于更加全面地了解台风诱发平流层重力波的波动特征. 相似文献
5.
利用2011年秋季无线电探空数据,采用矢端曲线法首次分析了新疆库尔勒地区下平流层重力波特征参量,得到36组准单色重力波的结果.结果统计显示：库尔勒秋季下平流层重力波垂直波长、水平波长平均值分别为2.8 km和580 km,固有频率平均值为1.74f.垂直传播方向以上传为主,约占78%,其中下传重力波水平波长较短,固有频率较高.水平传播方向以西北和东南为主,各占1/3,其中上传（下传）重力波水平传播方向以西北（东南）居多,这与热带低纬站点和其他中纬站点观测结果不同.与其他站点比较,库尔勒地区ŵ/f最小,中高纬地区水平波长、垂直波长随纬度增加大致有减小的趋势,库尔勒地区偏离这一趋势,波长偏大. 相似文献
6.
利用子午工程海南激光雷达对我国海南地区上空进行持续观测,通过3年的累积观测数据对我国低纬度地区重力波活动的季节分布特性进行研究,依据重力波线性理论对海南地区上空的大气密度扰动规律、空间功率谱及时间频率谱进行分析,并通过选择波长在1km至8km范围内具有特定波长以及具有波动周期为60 min至25min的特定频率的重力波辅助研究大气密度扰动的季节变化规律,总结得出海南地区重力波活动具有夏季大、春秋季小、而冬季依然频繁的季节性分布规律.结合海南地区特殊的地理位置与当地季节性气候特征分析得出海南地区上空重力波活动季节性变化的可能原因为青藏高原地形及我国南海地区存在的热带强对流与赤道潜流共同作用的结果. 相似文献
7.
利用中国科学院国家空间科学中心廊坊站(40.0°N,116.3°E)钠荧光多普勒激光雷达2011年至2013年共约82 h的钠原子数密度和垂直风观测数据,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特征.分析得到,90~100km处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处达到最大负值-1.47×10~8m~(-3)m·s~(-1),85~90km处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90km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1.40×10~8m~(-3)/h,该值超过了相同高度上模式计算流星烧蚀注入引起的钠原子产生率峰值,说明重力波耗散对钠层结构的形成具有重要影响.与美国SOR和Maui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显著的地域变化特征.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. 相似文献
8.
利用位于中国中纬地区6个OH气辉成像仪2012年1月至2013年12月两年的观测数据,我们研究分析了重力波传播特征.结果表明重力波的水平波长、观测周期和水平相速度分别主要分布于10~35km,4~12min和30~100m·s-1范围.夏季,重力波主要沿极向方向传播.然而,冬季,他们有向赤道方向和平行于赤道方向的传播趋势.同时,我们结合TRMM卫星和ECMWF数据,发现在夏季重力波的北向传播趋势可能主要由观测台站南方的对流活动导致.然而,对流层顶附近的急流可能在冬季重力波的主要传播方向方面做出较大贡献.分析结果也表明,低层-中层大气背景风的滤波效应仅在夏季与中国中纬地区重力波纬向传播方向各向异性吻合较好. 相似文献
9.
对流性重力波对中层大气环境有显著影响.重力波活动及重力波源的地理和季节性变化等信息是理解和模拟重力波效应的基础.卫星高光谱红外大气垂直探测器AIRS的4μm和15μm波段可用于识别30~40km高度范围和41km高度附近的重力波,其11μm通道可同步观测对流层深对流.观测个例表明,海面和陆面上空的平流层扰动影响范围均可达1000km,不同高度的扰动强度分布也存在差异.基于2007年6月至8月的AIRS观测资料,分析了东亚区域的对流层深对流活动和平流层的重力波,得到了深对流和重力波发生频率的水平分布.统计结果表明,东亚区域夏季夜间的深对流活动明显少于白天,但AIRS观测到的平流层重力波发生频率和扰动强度均显著大于白天,揭示了夜间对流层深对流诱发的平流层重力波在强度、范围等方面可能与白天存在显著差异.进一步对比分析表明,AIRS观测的平流层扰动高值区与深对流高值区明显不同.平流层重力波与对流层深对流之间的相关分析表明,在36°N以南的区域,41km高度上AIRS观测的重力波中,深对流云诱发的重力波的比例约为30%~100%.在10°N至36°N区间,90%的深对流均可诱发平流层重力波.分析得到的30~40km高度区间和41km高度附近的重力波水平分布对比表明,后一高度上的扰动强度明显大于前一高度,且前一高度在东南亚区域存在强扰动中心而在后一高度则没有.最后,给出了AIRS观测的几种典型形态的东亚区域平流层波动,表明了该区域平流层环境波动形态的复杂性和多样性. 相似文献
10.
本文利用中尺度数值模式WRF对2003年7月4-5日淮河流域特大暴雨过程进行了数值模拟,并利用高时空分辨率模拟结果资料,提取了暴雨中心区大气重力波频率、周期、水平波长、垂直波长、水平相速和群速等特征参数,分析了暴雨过程中重力波参数随时间的演变特征.结果表明,对此次暴雨强降水过程影响较大的重力波主要是发展的中 α 尺度波和中 β 尺度波,暴雨后期随着重力波的频散,周期和水平波长有减小趋势,频率有增大趋势.非降水区的重力波参数特征和降水中心区有明显不同,大气中小振幅的中 α 尺度和中 β 尺度重力波是否发展和暴雨强降水的发生关系密切. 相似文献
11.
利用我们建立的三维分层线性理论计算模式和中尺度数值模式ARPS, 分别研究了三维分层流动过双山脉地形产生的三维线性和非线性山脉重力波和大气船舶的结构特征及其形成机制.线性理论计算结果表明三维三层流动过双山脉地形时,两个山脉各自强迫出一个发散模态的山脉背风波,在第二个山脉背风面,三维三层流动过双山脉地形可以强迫出两个发散模态的拦截背风波,大大加强了对大气环流的拖曳作用.非线性数值模拟结果表明,流动过山所产生的非线性山脉重力波和大气船舶完全不同于三维分层线性理论计算模式所产生的山脉重力波和大气船舶的结构和特征,由于分层流体之间的非线性相互作用,三维三层流动过双山脉地形时,可在第二个山脉背风面激发4个发散模态的拦截背风波. 三维三层流动过双山脉地形所强迫的山脉重力波和大气船舶,具有同三维三层流动过孤立山脉所产生的山脉重力波和大气船舶完全不同的结构和特征,三维流动过双山脉地形对两个山脉之间的距离表现出极大的敏感性.对于相距较远的两个山脉,流动过双山脉所强迫的山脉重力波表现为4个发散模态的拦截背风波,波动的能量相对于相距较近的两个山脉能传播到更高的高度. 相似文献
12.
The ALOMAR SOUSY Radar operated at 53.5 MHz has been used in a five-beam configuration to study dynamical processes at gravity wave periods in the summer polar mesosphere. A case study of a gravity wave with a period of about 9 min is presented and analysed in some detail. The three-dimensional wave number vector is determined from the phase information of the 9-min velocity oscillations obtained in all beam directions and all range gates. The horizontal wavelengths in the north and east direction are estimated to be about 60 and 50 km, respectively. The echo power variations, simultaneously observed at different beam pointing positions, are investigated using cross-correlation analysis. The results show that these wave-associated variations lead to horizontal and vertical deformation of the echoing layers. The horizontal wavelength in the north-south direction, derived from the echo power modification, is in good agreement with the one obtained from the velocity analysis. 相似文献
13.
R. Werner K. Stebel G.H. Hansen U. Blum U.-P. Hoppe M. Gausa K.-H. Fricke 《Journal of Atmospheric and Solar》2007,69(17-18):2249
During the last two decades, important advances have been made in the investigation of gravity waves. However, more efforts are needed to study certain aspects of gravity waves. In the real atmosphere, gravity waves occur with different properties at different altitudes and, most often, simultaneously. In this case, when there is more than one dominant wave, the determination of gravity wave characteristics, such as the vertical wavelength and the phase velocity, is difficult. The interpretation of temperature perturbation plots versus the altitude and time as well as the application of the Fourier spectral analysis can produce errors.Exact knowledge of the wave characteristics is important both for determination of other characteristics, for example, the horizontal wave components, and for study of wave climatology. The wavelet analysis of vertical temperature profiles allows one to examine the wave's location in space. Up to now, gravity waves have been studied mainly by continuous wavelet transformation to determine dominant waves. We apply wavelet analysis to a time series of temperature profiles, observed by the ALOMAR ozone lidar at Andoya, Norway, and by the U. Bonn lidar system at ESRANGE, Sweden, both for determination of the dominant waves and for specifying the vertical wavelengths and the vertical component of the phase velocities. For this purpose, the wavelet amplitude spectra and the wavelet phase spectra are filtered and Hovmöller diagrams for dominant wavelengths are constructed. The advantage of this type of diagrams is that they give clear evidence for the localization of the dominant waves in space and time and for the development of their phase fronts. 相似文献
14.
O. N. Savina P. A. Bespalov V. O. Rapoport N. A. Ryzhov 《Geomagnetism and Aeronomy》2006,46(2):247-253
The nonlinear equation of the first order of the Riccati type has been obtained for the wave impedance of acoustic gravity waves in the nonisothermal atmosphere. The vertically nonuniform horizontal wind and the effect of viscosity on the horizontal components of the velocity field have been taken into account in the calculations. The boundary-value problem for the Riccati equation is defined by the boundary emission condition at high altitudes. Upon finding the wave impedance along with the generalized polarization relationship, all remaining disturbances of the atmospheric parameters related to acoustic gravity waves are found with the help of a simple integration. The results of using a developed formalism are illustrated by the numerical computation of acoustic gravity wave fields in the atmosphere with real vertical profiles of temperature and horizontal field velocity. 相似文献
15.
I. C. Simpson 《地震工程与结构动力学》1978,6(3):247-263
A two-dimensional soil-structure interaction analysis is carried out for transient Rayleigh surface waves that are incident on a structure. The structure is modelled by a three-degree of freedom rigid basemat to which is attached a flexible superstructure, modelled by a single mass-spring system. The structural responses to a given Rayleigh wave train are compared with those that would have been obtained if the free-field acceleration-time history had been applied as a normally incident body wave. The results clearly exhibit the [frequency filtering] effects of the rigid basemat on the incident Rayleigh waves. It is shown that, if seismic excitation of a structure is, in fact, due to Rayleigh surface waves, then an analysis assuming normally incident body waves can considerably over-estimate structural response, both at basemat level for horizontal and vertical motions and for vertical oscillations of the superstructure. However, in the examples considered here, relatively large rocking effects were induced by the Rayleigh waves, thus giving maximum horizontal accelerations in the superstructure that were of comparable magnitude for Rayleigh and normally incident body waves. 相似文献
16.
A theory of enhanced saturation of the gravity wave spectrum due to increases in atmospheric stability 总被引：1，自引：0，他引：1
In this paper we consider a vertical wavenumber spectrum of vertically propagating gravity waves impinging on a rapid increase in atmospheric stability. If the high-wavenumber range is saturated below the increase, as is usually observed, then the compression of vertical scales as the waves enter a region of higher stability results in that range becoming supersaturated, that is, the spectral amplitude becomes larger than the saturation limit. The supersaturated wave energy must then dissipate in a vertical distance of the order of a wavelength, resulting in an enhanced turbulent energy dissipation rate. If the wave spectrum is azimuthally anisotropic, the dissipation also results in an enhanced vertical divergence of the vertical flux of horizontal momentum and enhanced wave drag in the same region. Estimates of the enhanced dissipation rates and radar reflectivities appear to be consistent with the enhancements observed near the high-latitude summer mesopause. Estimates of the enhanced mean flow acceleration appear to be consistent with the wave drag that is needed near the tropopause and the high-latitude summer mesopause in large-scale models of the atmosphere. Thus, this process may play a significant role in determining the global effects of gravity waves on the large-scale circulation. 相似文献
17.
《Journal of Atmospheric and Solar》2008,70(7):991-1011
Using the technique developed by Gardner and Voelz [1987. Lidar studies of the nighttime sodium layer over Urbana, Illinois, 2. Gravity waves. Journal of Geophysical Research 92, 4673–4693] and a new method proposed by us, two groups of gravity wave parameters are extracted from 11 years sodium lidar measurements made at a southern low-latitude location. The wave occurrence frequencies, wave parameter distributions, and wave parameter relationships are given and compared with other lidar observations. The different lidar derived results can be attributed to different atmospheric parameters. The characteristics of these two groups of gravity waves are also compared, as well as that predicted by diffusive filtering theory, and we find the gravity wave relationships derived from our method are in better agreement with diffusive filtering theory predictions. 相似文献