1480型多普勒天气雷达中尺度气旋识别模块设计   总被引：2，自引：0，他引：2  

陶岚  顾松山  徐芬  夏文梅 《南京气象学院学报》2007,30(3):417-423

借鉴国内外中尺度气旋识别算法的研究成果特别是NSSL(National Severe Storm Laboratory)的中尺度气旋识别算法,结合多普勒天气雷达二次产品软件的特点,提出了改进的中尺度气旋识别算法,以动态链接库的形式,设计完成了中尺度气旋识别模块.对2002年5月27日安徽省北部地区的一次强对流天气过程的雷达资料进行了分析,并与北京敏视达(METSTAR)雷达有限公司Build 10.8软件系统生成的中尺度气旋产品进行了对比分析,结果表明该模块有比较好的识别能力,预警效果较好.  相似文献   

复杂地形城市冬季边界层气溶胶扩散和分布模拟   总被引：1，自引：5，他引：1  

郑飞  张镭  朱江  王慧 《高原气象》2007,26(3):532-540

着眼于城市冬季气溶胶扩散特征问题,针对地形复杂的兰州市及周边地区,开发了WRF模式,使之与包含了大气气溶胶辐射效应和气溶胶粒子扩散的综合大气边界层数值模式嵌套,以模拟城市冬季边界层气溶胶的扩散和分布规律。通过一个个例的模拟结果分析,揭示了兰州冬季气溶胶的扩散分布的如下特征;市区盆地内100 m以下存在东、西两个浓度高值中心,中心值为0.6~3.0 mg.m-3,往上浓度递减,1000 m高度处仅为0.02 mg.m-3。受排放源强、源高、气象场等因素的共同影响,白天盆地内气溶胶浓度随高度和时间的变化强烈,白天浓度随时间最大变化幅度为1.0 mg.m-3。气溶胶输送扩散高度可达到600~800 m,此高度以上浓度值很小。代表性测点上模拟的气溶胶浓度廓线表明,中午浓度达到最高,垂直扩散最强。这些结果与以往的烟雾层高度观测和气溶胶光学厚度观测结果吻合。夜间,盆地内气溶胶浓度随高度和时间的变化减弱,气溶胶输送扩散高度在400~500m,夜间浓度随时间变化平均幅度为0.05 mg.m-3。  相似文献   

增强气候诊断及预测程序通用性的一种方法     

余卫东  董博  陈巧  常军 《河南气象》2007,(2)

针对现有气候统计诊断与预测程序在通用性方面的不足,以线性趋势估计的源程序为例,介绍了在微机平台上,利用Fortran 90的动态数组特性,通过增加参数控制文件增强该程序通用性的思路和方法,并利用V isualBasic语言对改进后的程序进行可视化设计,增强了程序的易用性。  相似文献   

亚洲夏季风系统成员与西太平洋副高的相关特征分析   总被引：9，自引：8，他引：9  

余丹丹  张韧  洪梅  闵锦忠  郭品文 《热带气象学报》2007,23(1):78-84

利用500hPa月平均高度距平场派生出涡度变化、经向风切变、纬向风切变等变量场。从1958～2001年6月500hPa月平均高度距平场及其派生变量场中选取预报因子,并将各个场中的因子分别作EOF分解,得到浓缩了初选因子变量大部分信息的综合预报因子,用以建立同月的广西月降水量的BP神经网络预报模型。进而利用2002～2005年月动力延伸集合预报产品及其派生变量,对广西6月降水量作BP神经网络降尺度释用预报。作为对比试验,以相同的预报量,从1957～2000年5～12月及1958～2001年1～4月500hPa月平均高度距平场中选取预报因子,并作相同处理,建立前期综合因子的广西6月降水量BP神经网络预报模型。独立样本试验结果表明,利用同期综合因子建立的BP神经网络降尺度预报模型的拟合精度优于利用前期综合因子建立的预报模型,但预报效果依赖于月动力延伸集合预报产品。  相似文献   

无线GIS空间数据动态副本管理研究   总被引：2，自引：0，他引：2  

林承达  孟令奎  彭溢 《武汉大学学报(信息科学版)》2007,32(3):263-266

针对GIS海量空间数据更新要求，研究了无线网络环境下空间数据传输和存储的副本动态复制与管理技术。通过分析空间数据移动复制服务策略，设计了基于无线网络的动态副本管理系统（DRMS）来实现空间数据的移动动态复制，并研究副本管理模型和副本更新算法，保证了无线网络传输的稳定性。  相似文献   

胶西北金成矿区He、Ar同位素组成及成矿流体来源研究     

王金辉 《岩石矿物学杂志》2020,39(2):172-182

胶东半岛西北地区是我国重要的金成矿区,主要受三山岛断裂、焦家断裂、招平断裂带控制。为探讨3条主要成矿带成矿流体的来源与区别,对成矿带内典型矿床载金黄铁矿中流体包裹体进行了He、Ar同位素测试。结合前人数据表明三山岛成矿带3He/4He均值为1.95 Ra,焦家成矿带^3He/^4He均值为1.74 Ra,招平成矿带^3He/^4He均值为1.54 Ra,从西往东逐渐降低,说明地幔流体参与成矿自西往东逐渐降低。黄铁矿流体包裹体中放射性成因Ar所占比例范围三山岛成矿带1.17%~87.12%,平均33.04%,焦家成矿带15.57%~90.00%,平均55.75%,招平成矿带7.94%~92.69%,平均44.23%,说明在成矿过程中,地壳成矿流体参与成矿作用焦家成矿带最高,招平成矿带次之,三山岛成矿带最低。结合H、O稳定同位素研究,认为成矿流体主要来源于地壳,并有地幔流体加入,具地壳流体和地幔流体混合特征,上升过程中可能还有少量大气降水的参与。  相似文献   

High-velocity stars from decay of small stellar systems     

L. G. Kiseleva    J. Colin    B. Dauphole  & P. Eggleton 《Monthly notices of the Royal Astronomical Society》1998,301(3):759-766

In this paper we present numerical results on the decay of small stellar systems under different initial conditions (multiplicity 3 ≤  N  ≤ 10, and various mass spectra, initial velocities and initial configurations). The numerical treatment uses the CHAIN1 code (Mikkola &38; Aarseth). Particular attention is paid to the distribution of high-velocity escapers: we define these as stars with velocity above 30 km s⁻¹. These numerical experiments confirm that small N -body systems are dynamically unstable and produce cascades of escapers in the process of their decay. It is shown that the fraction of stars that escape from small dense stellar systems with an escape velocity greater than 30 km s⁻¹ is ∼1 per cent for all systems treated here. This relatively small fraction must be considered in relation to the rate of star formation in the Galaxy in small groups: this could explain some moderately high-velocity stars observed in the Galactic disc and possibly some young stars with relatively high metallicity in the thick disc.  相似文献   

Stream overflow and dwarf nova eruptions     

M. R. Schreiber  & F. V. Hessman 《Monthly notices of the Royal Astronomical Society》1998,301(3):626-630

We consider the effects of accretion stream overflow on the viscous dynamics of accretion discs in dwarf novae. If the stream from the secondary star is geometrically thick enough, some fraction of its material can flow over and under the disc. The mass and specific angular momentum of the stream are then deposited not only at the point of collision with the outer disc, but also at those radii in the inner disc with geometric heights that are large enough to intercept the residual stream, or near the radius where the disc has the same specific angular momentum as the stream. The overflowing stream can alter the behaviour of heating fronts and cooling fronts in the disc. If the mass fraction of the overflowing stream is of order tens of per cent, the deposition of mass in the inner parts of the disc is sufficient to change the character of the eruption light curves significantly.  相似文献   

The destructive effects of binary encounters on red giants in the Galactic Centre     

Melvyn B. Davies  Richard Blackwell  Vernon C. Bailey  & Steinn Sigurdsson 《Monthly notices of the Royal Astronomical Society》1998,301(3):745-753

We consider the destructive effects of encounters between binaries and red giant stars in the Galactic Centre. Such encounters may explain the observed depletion of luminous red giants within the central 0.2 pc of the galaxy. We consider encounters involving 2- and 8-M⊙ red giants, and thus span the range of stellar masses contributing to the most luminous red giants observed in the Galactic Centre. To explore the phase space of encounters thoroughly, we simulate 18 × 10³ encounters using a modified four-body code in which the red giant core and components of the binary are treated as point masses, and where the envelope configuration is assumed to remain static throughout the encounter. We then rerun a small number of encounters with a smoothed particle hydrodynamics (SPH) code to confirm the reliability of conclusions drawn from the four-body runs. We see two possible pathways to red giant destruction. A large fraction of encounters lead to the formation of common-envelope systems, where two compact objects (drawn from the red giant core and the components of the original binary) form a binary within a common gaseous envelope, whilst the third body is ejected. The destruction of the red giant will then follow when the envelope is ejected as the binary hardens. In a smaller number of encounters, the intruding binary passes through the star and ejects the red giant core from the envelope. The red giant envelope will then disperse on short time-scales. We compute the time-scales for both of these processes to occur in the Galactic Centre for a variety of binary populations.  相似文献   

The tilt of the Fundamental Plane of early-type galaxies: wavelength dependence     

M. Scodeggio    G. Gavazzi    E. Belsole    D. Pierini  & A. Boselli 《Monthly notices of the Royal Astronomical Society》1998,301(4):1001-1018

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