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非静力模式中几种垂直网格计算特性的对比研究 总被引：8，自引：0，他引：8
从非静力滞弹性方程组出发，将惯性重力波的水平波长分几百公里、几十公里和几公里三种情况，从频率、群速和各速的垂直尺度范围等方面对现有的几种垂直网格进行比较讨论。结果表明：在非静力模式中，CP网格和LZ网格适合于各种不同水平尺度惯性重力波的模拟；L网格和LY网格适合于水平尺度为几十公里以上的惯性重力波的模拟；LTS网格和CPTS网格比较适合于水平尺度的几十公里以下的惯性重力波的模拟。 相似文献
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为了研究垂直变量配置对静力适应过程的影响,本文从描写静力适应过程的方程组出发,分别在将所有变量置于整层上的非跳点N网格;将垂直速度和温度放置在整层,水平速度、气压和密度等变量放置在半层的Charney Phillips跳点网格(CP网格);将水平速度、气压和温度放置在整层,将垂直速度和密度放置在半层的Lorenz跳点网格(L网格);将密度变量放置在整层的Charney Phillips跳点网格(CP_N网格);将密度放置在整层的Lorenz跳点网格(L_N网格)上进行离散,垂直格距分1 km、0.5 km、0.2 km和0.01 km,研究了在这5种网格上产生的频率和垂直群速的相对误差。结果表明:(1)L_N网格和CP网格是完全等效的两种网格。(2)不论垂直格距为多少,CP网格和L网格的误差都是最小,N网格次之,CP_N网格的误差最大。(3)随着垂直格距的减少,在这几种网格上产生的误差都在减小。对于CP网格、L网格和N网格,在水平长波和垂直短波处产生的误差较大。而CP_N网格对水平波长变化不敏感,垂直波长越短,误差越大。(4)当垂直格距为0.01 km时,这几种网格都对水平波长的变化不敏感了,仅对垂直波长敏感。(5)CP网格、L_N网格和L网格在描写静力适应过程和斜压地转适应过程都是误差最小的垂直变量配置方案,因此在非静力完全可压缩深层大气数值预报模式中应优先选择这3种方案。 相似文献
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在线性斜压原始方程组的基础上，从频率和群速方面讨论了由水平网格 (C、Z网格) 和垂直网格 (L、CP、LZ、LY网格) 组合而成的几种三维网格 (C/L、C/CP、Z/LZ、Z/LY) 的计算频散性并分析了各种网格出现偏差的原因，结果表明三维网格C/CP (水平网格为C网格垂直网格为Charney-Phillips网格) 与Z/LZ（水平网格为Z网格垂直网格为LZ网格）计算频散性能较好。从而为原始方程大气模式选取三维网格提供指导。 相似文献
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由于中尺度模式中采用不同的三维变量配置,必将产生不同的预报和模拟效果.怎样的三维变量分布,才能产生最佳的模拟效果呢?一直没有人从事这方面的研究.为此,在线性非静力滞弹性方程组的基础上,从频率、水平群速和垂直群速方面将中尺度模式中常见的四种三维网格的计算频散性与解析解的情况进行了对比,主要采用图示比较的方法.结果表明:总的来看三维网格C/CP计算频散性能最好,Z/LZ和Z/LY网格次之,C/L网格最差.因此设计非静力斜压模式时,应尽量采用C/CP网格.但C/CP网格对水平波长较短的波,误差相对要大些.如果模拟的波动水平尺度较小时,为减少误差,水平格距要减小.另外C/CP网格主要用在有限差分模式中;要考虑谱模式中的变量配置时,应把C/CP网格和Z/LZ网格或Z/LY网格结合起来使用. 相似文献
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球面上斜压原始方程组保持总有效能量守恒的差分格式 总被引：8，自引：9，他引：8
本文从标准层结近似下球面上的斜压原始方程组出发,针对两类常用的网格系统——C-网格和B-网格,分别设计出可以保持总动能、总有效位能和总有效表面位能之和守恒的差分格式.同时,讨论了定义在交错网格上的差分和平均算子的一些很有用的性质. 相似文献
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Mean Flow–Storm Track Relationship and Rossby Wave Breaking in Two Types of El-Nino简 总被引：1，自引：0，他引：1
The features of large-scale circulation, storm tracks and the dynamical relationship between them were examined by investigating Rossby wave breaking （RWB） processes associated with Eastern Pacific （EP） and Central Pacific （CP） E1-Nifio. During EP E1-Nino, the geopotential height anomaly at 500 hPa （Z500） exhibits a Pacific-North America （PNA） pattern. During CP EI-Nifio, the Z500 anomaly shows a north positive-south negative pattern over the North Pacific. The anomalous distributions of baroclinicity and storm track are consistent with those of upper-level zonal wind for both EP and CP EI-Nino, suggesting impacts of mean flow on storm track variability. Anticyclonic wave breaking （AWB） oczurs less frequently in EP EI-Nino years, while cyclonic wave breaking （CWB） occurs more frequently in CP EI-Nino years over the North Pacific sector. Outside the North Pacific, more CWB events occur over North America during EP Ei-NiNo. When AWB events occur less frequently over the North Pacific during EP EI-Nino, Z500 decreases locally and the zonal wind is strengthened （weakened） to the south （north）. This is because AWB events reflect a monopoie high anomaly at the centroid of breaking events. When CWB events occur more frequently over the North Pacific under CP EI-Nino conditions, and over North America under EP EI-Nino condition, Z500 increases （decreases） to the northeast （southwest）, since CWB events are related to a northeast-southwest dipole Z500 anomaly. The anomalous RWB events act to invigorate and reinforce the circulation anomalies over the North Pacific-North America region linked with the two types of EI-Nino. 相似文献
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Short-range forecast of heavy precipitation and strong wind using the convection-allowing WRF models
N. F. Vel’tishchev V. D. Zhupanov Yu. B. Pavlyukov 《Russian Meteorology and Hydrology》2011,36(1):1-10
The results are stated of estimation of short-range forecasting of heavy precipitation (P ≥ 10 mm/12 hours) and strong wind at the height of 10 m (V ≥ 10 m/s) using three nonhydrostatic models from the WRF family: ARW, ARW Glob, and NMM. The forecasts on the basis of all three models were carried out using two grids. The horizontal resolution of external grids varied from 9 to 16.5 km and that of the nested grids, from 3 to 5.5 km. For the ARW and NMM models, the values at side boundaries of external nested grids were taken from the forecasts on the basis of the global GFS NCEP model and for the ARW Glob model, from the global forecasts based on this model. The convection parameterization was turned off at nested grids for all models. The forecasts of heavy precipitation and strong wind at nested grids over the European territory of Russia were estimated from the radar and station measurements in summer 2008. It is obtained that all three models reproduce well enough the mesoscale convective systems and associated areas of heavy precipitation and strong wind but they have common shortcomings: they overestimate the amount and area of heavy precipitation and underestimate the strong wind speed. To a lesser degree, these shortcomings are typical of the ARW model. The possible reasons for systematic errors in the forecasts are discussed. 相似文献
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J. M. Popović Dr. S. Ničković M. B. Gavrilov 《Meteorology and Atmospheric Physics》1996,58(1-4):41-49
Summary Finite-difference analysis of Rossby modes has been performed for two staggered hexagonal grids. The solutions are compared with those obtained in analytical case and for rectangular grids. The result for one of the selected hexagonal grids better fits to the analytical solution then the results for the other considered grids. The obtained results may contribute to better understanding of the appropriateness of hexagonal grids in atmospheric and oceanographic modeling and numerical computations.With 6 Figures 相似文献
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毫米波测云雷达在降雪观测中的应用初步分析 总被引：2，自引：0，他引：2
本文利用毫米波云雷达联合称重式雨量计、气球探空和S波段天气雷达在北京对2015年11月三次降雪进行了观测,以2015年11月22~23日降雪过程为例,主要从降雪系统的宏观结构特征、微物理变化以及毫米波雷达在降雪探测中电磁波衰减情况、雪粒子含水量和地面降雪量估测几方面进行初步分析。结果表明:（1）毫米波云雷达具有高时空分辨率,能对降雪系统进行精细化探测,在降雪系统发展最旺盛的阶段能够通过反射率（Z）、退极化比（LDR）和径向速度（V）初步判断出云中是否含有过冷液滴;（2）降雪回波强度最大值能反映整层云系中含水量最大的区域,当最大值Z大于20 dBZ时,最大值的大小、最大值持续时间、最大值出现的高度与地面降水量成正相关,速度最大值表示云中粒子上升最大速度（速度为正时）或者粒子下落的最小速度（速度为负时）,主要分布在－0.5~2 m s?1,速度最小值表示粒子下落的最大速度,主要在－3~－1 m s?1;（3）随着高度增加反射率的垂直廓线会出现多个峰值,这是由于不同高度层风速分布不均造成的,降雪回波这种特点比降雨回波更明显;（4）对比Ka与S波段雷达反射率可知,两雷达反射率平均差值小于2.5 dBZ,Ka波段反射率略大S波段雷达反射率;（5）降雪量反演与地面降雪量仪数据对比,逐小时降雪量反演精度为20.38%,累计降雪量反演误差为6.58%,24小时累计降雪量绝对误差为1.9 mm,说明云雷达估算累计降雪量具有较高的可行性,能够很准确的反映地面实际降雪情况,当降雪系统发展旺盛时,雪粒子含水量分布在0.05~0.15 g m?3,在降雪初期或者降雪系统消散期,雪粒子含水量一般小于0.04 g m?3,能够很好地反映出整层降雪回波的雪粒子含水量。这些云雷达在降雪观测中的应用和初步分析结果可以更好的地了解降雪系统宏微观结构,为云模式的发展和人工影响天气中增雪潜力评估提供一些参考。 相似文献
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Summary A simple two-dimensional quasi-geostrophic linearized model of the atmosphere is used to investigate the behaviour of the quasi-geostrophic modes for five horizontal rectangular grids. Numerical expressions for frequencies of Rossby waves for all grids are evaluated. It was found that the B and C grids produce only negative frequencies as well as the continuous case. The D grid has negative and zero frequencies. Finally, it was found that the A and E grids produce positive frequencies and eastward moving Rossby waves.With 2 Figures 相似文献