小波分析在重力界面反演中的应用   总被引：1，自引：0，他引：1  

张会战  方剑  张子占 《武汉大学学报(信息科学版)》2006,31(3):233-236

基于Parker-Oldenburg反演方法，分析了低通滤波器B（K）的不同阈值对位场分离的影响。分别采用小波变换和低通滤波对青藏高原地区布格重力异常进行了位场分解和莫霍面反演，并将反演结果与地震资料作比较。结果表明，在重力位场分解中小波多尺度分解可以代替低通滤波器B（K），避免了闻值的选取。  相似文献   

焦作市4—9月短期降水精细化预报系统   总被引：2，自引：0，他引：2  

司福意  刘跃红  黄克磊  罗楠  李艳红  苗卫东 《气象》2006,32(8):77-80

在降水时空变化研究的基础上，完成辖区降水区划；用计算机识别T213风场中槽线、切变线等影响系统，并按其相对于预报站方位，确定对其影响强度指数，组合预报因子，建立判别方程，制作分县0～12小时、12～24小时降水分级预报。经检验，系统对降水落区有较强预报能力。  相似文献   

年代际气候变化研究进展   总被引：5，自引：9，他引：5  

宋巧云  魏凤英 《气象科技》2006,34(1):1-6

概述了全球尺度、我国大范围区域及长江中下游梅雨的年代际气候变化的一些研究进展,重点介绍了近期我国气象工作者有关这方面研究的一些成果。指出:①全球尺度的大气、海洋及气温变化不仅存在明显的年际变化,而且年代际变化也十分显著;②受全球气候年代际变化的影响,中国气候也存在多时间尺度的变化特征,但气候的年代际变化特征与全球气候年代际变化有不同之处;③长江中下游梅雨气候变异不仅与海-气相互作用密切相关,而且海洋的年代际变化也是梅雨异常变化的重要气候背景;④年代际尺度变化在全球变暖改变区域气候特征的过程中的贡献、年代际气候变化的形成及作用机制,特别是长江中下游梅雨的年代际变化的成因和机制都是仍需继续加强研究的问题。  相似文献   

捷联惯导系统四元数转换误差分析     

毛克诚  孙付平 《测绘学院学报》2006,(4)

捷联惯性导航系统中,根据四元数与直余弦矩阵的关系可以得到3种转换矩阵。充分分析了这3种转换方案所产生的误差。并在恒定角速率下对3种不同转换矩阵中漂移误差、不对称误差和刻度误差进行评估,最后通过仿真验证了分析结果。  相似文献   

A Large-Eddy Simulation and Lagrangian Stochastic Study of Heavy Particle Dispersion in the Convective Boundary Layer   总被引：4，自引：1，他引：4  

Xuhui Cai  Rui Zhang  Yan LI 《Boundary-Layer Meteorology》2006,120(3):413-435

Large-eddy simulation and Lagrangian stochastic dispersion models were used to study heavy particle dispersion in the convective boundary layer (CBL). The effects of various geostrophic winds, particle diameters, and subgrid-scale (SGS) turbulence were investigated. Results showed an obvious depression in the vertical dispersion of heavy particles in the CBL and major vertical stratification in the distribution of particle concentrations, relative to the passive dispersion. Stronger geostrophic winds tended to increase the dispersion of heavy particles in the lower CBL. The SGS turbulence, particularly near the surface, markedly influenced the dispersion of heavy particles in the CBL. For reference, simulations using passive particles were also conducted; these simulation results agreed well with results from previous convective tank experiments and numerical simulations.  相似文献   

Turbulence Scale Dependence of the Richardson Constant in Lagrangian Stochastic Models     

A. Maurizi  G. Pagnini  F. Tampieri 《Boundary-Layer Meteorology》2006,118(1):55-68

We investigate the relative dispersion properties of the well-mixed class of Lagrangian stochastic models. Dimensional analysis shows that, given a model in the class, its properties depend solely on a non-dimensional parameter, which measures the relative weight of Lagrangian-to-Eulerian scales. This parameter is formulated in terms of Kolmogorov constants, and model properties are then studied by modifying its value in a range that contains the experimental variability. Large variations are found for the quantity, g* = 2gC₀^{− 1}, where g is the Richardson constant.  相似文献   

“05．6”广西持续性大暴雨成因分析   总被引：17，自引：0，他引：17  

黎惠金 《广西气象》2006,27(3):22-25

利用常规资料、T213初始场及6h预报场、卫星云图等资料，用中尺度分析方法，并配合诊断分析，对广西“05.6”持续性大暴雨成因进行了初步探讨。结果表明：这次过程是在稳定的大尺度环流形势和有利的物理量场条件下发生，是大、中尺度天气系统相互作用的结果，具有典型的中尺度性质，表现出强降雨的不均匀性、突发性和局地性，是中尺度天气系统活动的结果。  相似文献   

THE RELATIONSHIP BETWEEN SCS SUMMER MONSOON INTENSITY AND OCEANIC THERMODYNAMIC VARIABLES AT DIFFERENT TIME SCALE     

谷德军  纪忠萍  王东晓  梁建茵  方一川 《热带气象学报(英文版)》2007,13(1):85-88

The oscillation characteristics of 1948 - 2003 South China Sea (SCS) summer monsoon intensity (SCSSMI) is analyzed by wavelet transform and the relationship between SCSSMI filtered by Lanczos filter at different time scale and oceanic thermal conditions is studied. The results show that SCSSMI exhibits dominant interannual (about 4 a), decadal (about 9 a) and interdecadal (about 38 a) oscillation periods. The interannual variation is the strongest and the interdecadal variation the weakest. The region of significant correlation between SCS summer monsoon intensity and oceanic thermodynamic variables at different time scale is greatly different. Significant correlation area of interannual variation of SCSSMI is concentrated in near equatorial region. Corresponding correlation displays quasi-biannual variability. If positive anomalies of SST and the depth of thermocline happen in eastern equatorial Indian Ocean and western equatorial Pacific, and negative anomalies of SST and the depth of thermocline happen in western equatorial Indian Ocean and eastern equatorial Pacific in previous autumn and winter, the interannual variation of SCSSMI will enhance. If the condition is contrary, interannual variation of SCSSMI will weaken. The interannual variation of SCSSMI will influence SST. The region surrounding SCS and east of Australia shows significantly negative correlation in autumn, and significantly positive correlation exhibits in west equatorial Indian Ocean, eastern equatorial Pacific and equatorial Atlantic in winter. The decadal variation of SCSSMI is modulated by PDO. Interdecadal variation of SCSSMI is relevant to the global warming and PDO.  相似文献   

Towards urbanisation of the non-hydrostatic numerical weather prediction model Lokalmodell (LM)     

Lina Neunhäuserer  Barbara Fay  Matthias Raschendorfer 《Boundary-Layer Meteorology》2007,124(1):81-97

Numerical weather prediction models are increasingly employed for providing meteorological data for urban air quality applications. Model resolution, physiographic parameters and surface-layer parameterisations need to be adapted to the requirements of the urban boundary layer. The Lokalmodell of the German Weather Service was triple-nested down to a horizontal grid resolution of 1.1 km, urbanised physiographic parameters were implemented, and an additional anthropogenic heat source was introduced. Results of a sensitivity study for a spring dust episode in Helsinki show a clear urbanisation effect of these measures on temperature, humidity and the partitioning of surface fluxes, leading to an increased Bowen ratio and heat storage and an urban heat island effect.  相似文献   

Landscape governance: The “politics of scale” and the “natural” conditions of places     

Christoph Görg 《Geoforum》2007,38(5):954-966

Governance has become an iridescent concept in recent years. The term is widely used in almost all social-science disciplines as well as in the political process. The intention of this paper is not so much to clarify these sometimes vague meanings but to highlight some characteristics of environmental governance connected with the restructuring of the spatial dimensions of politics. It starts from the assumption that the quest for multi-level decision making is particularly pressing for environmental governance. However, multi-level governance raises concern about the constitution of various spatial levels and their relationships with each other, as discussed under the term of “politics of scale”. Moreover, it is argued that for environmental governance the spatial reference is strongly connected with another challenge, which concerns the question of how to deal with the biophysical conditions of particular places. The term landscape governance is introduced to tackle this question without referring to an ontologically given space. Thus, landscape governance deals with the interconnections between socially constructed spaces (the politics of scale) and “natural” conditions of places. For this task, the concept of societal relationships with nature is introduced and applied to the term “landscape” as a bridging concept between social and natural sciences. The paper illustrates the approach of landscape governance with examples of problem-oriented interdisciplinary research at the UFZ-Centre for Environmental research in Leipzig, Germany.  相似文献