交叉相关算法在强对流天气临近预报中的应用   总被引：4，自引：0，他引：4  

曾小团  梁巧倩  农孟松  冯业荣  许向春  陈业国 《气象》2010,36(1):31-40

利用"雨燕"临近预报系统的雷达回波外推算法,对三次强对流个例的3 km CAPPI反射率因子、回波顶和垂直累积液态含水量进行0～1小时外推预测,将预测结果和组合阈值比较进行强对流天气预警区域预报试验。资料来源于CINRAD-SB雷达基数据经RPG算法处理得到的雷达产品数据。所用的方法是在扩展后的交叉相关追踪算法基础上实现雷达回波移动预测。试验结果表明:3 km CAPPI反射率因子、回波顶和垂直累积液态含水量雷达产品与实况有较好的吻合,能较好地预报出回波的形状、变化趋势和移动方向,回波的范围、位置和强度中心与实况相似,外推时间越短,预报效果越好。交叉相关追踪算法外推得到的雷达回波结果在0～1 h内是可用的;外推预测结果经过组合阈值的过滤后,得出的强对流天气预警区域预警结果也是可行的,对强对流天气临近预报有一定指示意义。  相似文献   

固体矿产勘查中矿体外推问题探讨          下载免费PDF全文

武晗 《地质找矿论丛》2017,32(3):505-508

固体矿产勘查储量计算过程中,矿体圈连时不可避免地会涉及到矿体外推的地质问题。其中,矿体外推的介质为储量计算剖面图和矿体中段水平投影图,矿体外推方式根据外推介质的不同分为沿走向外推和沿倾向外推。此外,根据有无探矿工程的限制可分为有限外推和无限外推,矿体外推起点为有探矿工程控制的矿体边缘样品工程,矿体外推长度分为"尖灭1/2工程间距、尖推=1/2工程间距、平推=1/4工程间距",外推矿体任何部位厚度必须小于矿体外推起点处矿体厚度。矿体外推与资源/储量分类关系密切,一般情况下外推矿体的资源量类型应为333。  相似文献   

Absolute Sea Level Surface Modeling for the Mediterranean from Satellite Altimeter and Tide Gauge Measurements     

Marijan Grgić  Robert Steven Nerem  Tomislav Bašić 《Marine Geodesy》2017,40(4):239-258

Changes in the height of the ocean can be described through the relative and absolute sea level changes depending on the geodetic reference the sea level records are related to. Satellite altimetry provides absolute sea level (ASL) measurements related to the global geodetic reference, whereas tide gauges provide relative sea level (RSL) measurements related to the adjacent land. This study aims at computing the ASL surfaces for different time epochs from combined satellite altimeter and tide gauge records. A method of sea level data fusion is proposed to enable modeling of the impact of present and future sea level changes on the coast. Sea surface modeling was investigated for ten different gridding methods commonly used for the interpolation of altimeter data over the open ocean and extrapolation over the coastal zones. The performance of gridding methods was assessed based on the comparison of the gridded altimeter data and corrected tide gauge measurements. Finally, the sea level surfaces related to the GRS80 global reference ellipsoid were computed for the Mediterranean Sea over the altimeter period. In addition, the current sea level trends were estimated from both sea level measurements.  相似文献   

串联F-K加相移插值法偏移          下载免费PDF全文

涂国田 《地球物理学报》1992,35(6):762-770

本文介绍的偏移成像方法为递归F-K法、相移插值法及串联偏移技术的有效结合,简称CFPI法.该方法中,波场外推采用相移插值法中递归向下延拓方式,而每一延拓层间的成像则用文中给出的常速F-K加剩余速度F-K偏移,通过与横向速度变化有关的插值来实现,该过程用FFT完成.该方法可采用较大的延拓步长速归向下外推与成像.理论分析及实际计算结果比较表明,该算法效率远高于相移插值法偏移.  相似文献   

GRAPES模式后处理技术改进应用研究     

佟华  胡江林  张玉涛 《气象科技》2020,48(4):511-517

详细梳理了GRAEPS模式后处理系统的计算方案,进行了GRAPES模式后处理中海平面气压计算方案的改进,温度垂直插值方案的改进以及位势高度的垂直插值外插方案的改进等。假定温度廓线随地形高度变化并满足静力平衡条件,对海平面气压及位势高度外插进行改进,改进后海平面气压和低层等压面的位势高度场在青藏高原和南美洲西部等大地形处改进明显,均方根误差和距平相关系数改进较大并通过显著性检验。对温度垂直插值采用的原始插值层进行改进,使得高层等压面温度场的准确性进一步提高,统计检验评分在各区域都有不同程度的提高,尤其是热带地区和东亚地区高层温度场改善明显。这些都为模式产品用户提供了更可靠的数值模式产品。  相似文献   

基于单一圆轨道的锥束投影的精确重建的可能性     

尤江生 《CT理论与应用研究》1997,6(4):41-45

本文介绍了一种可以对来自于单一圆轨道的锥束投影数据进行精确重建的分析方法。特别是，通过利用光谱外推技术获得相应的重建算法。这一工作总结了Ｔｕｙ充分条件和Ｓｍｉｔｈ充要条件，并且该分析方法对解决数据不完整的问题是有意义。  相似文献   

3D wavefield extrapolation with optimal separable approximation     

Zhang Zhifu Meng Xiaohong Liu Hong Chen Jingbo Li YouMing 《应用地球物理》2006,3(4):218-225

An accurate and wide-angle one-way propagator for wavefield extrapolation is an important topic for research on wave-equation prestack depth migration in the presence of large and rapid velocity variations. Based on the optimal separable approximation presented in this paper, the mixed domain algorithm with forward and inverse Fourier transforms is used to construct the 3D one-way wavefield extrapolation operator. This operator separates variables in the wavenumber and spatial domains. The phase shift operation is implemented in the wavenumber domain while the time delay for lateral velocity variation is corrected in the spatial domain. The impulse responses of the one-way wave operator show that the numeric computation is consistent with the theoretical value for each velocity, revealing that the operator constructed with the optimal separable approximation can be applied to lateral velocity variations for the case of small steps. Imaging results of the SEG/EAGE model and field data indicate that the new method can be used to image complex structure.  相似文献   

A modified imaging principle for true-amplitude wave-equation migration     

D. Kiyashchenko  R.-E. Plessix  B. Kashtan  V. Troyan 《Geophysical Journal International》2007,168(3):1093-1104

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A semi-implicit semi-Lagrangian global nonhydrostatic model and the polar discretization scheme   总被引：2，自引：0，他引：2  

YANG XueSheng  CHEN JiaBin  HU JiangLin  CHEN DeHui  SHEN XueShun  ZHANG HongLiang State Key Laboratory of Severe Weather  Chinese Academy of Meteorological Sciences  Beijing  China  State Key Laboratory of Numerical Modeling for Atmospheric Sciences  Geophysical Fluid Dynamics  Institute of Atmospheric Physics  Beijing  China 《中国科学D辑(英文版)》2007,50(12):1885-1891

The Global/Regional Assimilation and PrEdiction System(GRAPES) is a newly developed global non-hydrostatic numerical prediction model,which will become the next generation medium-range opera-tional model at China Meteorological Administration(CMA).The dynamic framework of GRAPES is featuring with fully compressible equations,nonhydrostatic or hydrostatic optionally,two-level time semi-Lagrangian and semi-implicit time integration,Charney-Phillips vertical staggering,and complex three-dimensional pre-conditioned Helmholtz solver,etc.Concerning the singularity of horizontal momentum equations at the poles,the polar discretization schemes are described,which include adoption of Arakawa C horizontal grid with ν at poles,incorporation of polar filtering to maintain the computational stability,the correction to Helmholtz equation near the poles,as well as the treatment of semi-Lagrangian interpolation to improve the departure point accuracy,etc.The balanced flow tests validate the rationality of the treatment of semi-Lagrangian departure point calculation and the polar discretization during long time integration.Held and Suarez tests show that the conservation proper-ties of GRAPES model are quite good.  相似文献   

二阶精度半隐式半拉格朗日轨迹计算和时间积分方案在GRAPES区域模式中的应用     

张旭  黄伟  陈葆德 《气象学报》2015,73(3):557-565

将两时间层稳定外插方案(Stable Extrapolation Two-Time-Level Scheme,SETTLS)引入GRAPES区域模式,并将其用于上游点和非线性项的时间外插计算。对线性项采用二阶精度的非中央权重时间平均,并取等温参考大气的温度大于实际大气平均温度,以保证半隐式积分方案的稳定性。原GRAPES时间积分方案对线性项做一阶非中央权重时间平均,对参考大气的选择并无限制,而为保证稳定性,须取较大的非中央权重系数,但非中央权重系数会对低波数波动产生较强的衰减作用。理想试验结果表明,相比原GRAPES半隐式半拉格朗日(SISL)时间积分方案,新SISL时间积分方案计算稳定且对波动的衰减作用较弱。  相似文献