几种统计相似方法的适用性比较

针对前人对各种相似性度量的预报检验结果,从公式出发,分析证明了相似离度与海明距离具有相同性质,探讨了相似离度在相似预报中使用的局限性。利用2010年5月1—30日08时东亚区域850 hPa高度场96个站点资料,对几个常用相似量及作者提出的新相似量进行相似选择试验,结果表明：（1）相似离度与海明距离非常接近,选出的相似样本80%以上是相同的;（2）相似离度与相关系数差异最大,选出的相似样本70%以上是不同的;（3）新相似量与相关系数较接近,60%是相同的。相似离度与海明距离反映的是样本间＂距离＂的接近程度,相关系数和新相似量反映的是样本间的形状接近程度。     

基于相似离度的相似预报系统

相似离度法是短期气候预测中常用的预报方法之一,该方法能够同时考虑环流场之间在形态和数值两方面的相似情况,是一种比较全面客观的相似衡量标准.依据相似离度的原理,利用可视化编程工具Visual Basic6.0,开发了分析500 hPa高度场相似离度并结合本地资料进行降水量预报的业务系统.     

热带气旋环境场相似检索方法的对比分析

比较了欧氏距离、相似离度、相似系数、相关系数及最优相似系数等作为气象格点场相似性度量的适用性,结果发现以“距离”为主的算法无法准确地反映环境场中的一些特定系统的位置和强度,相似检索效果较差;而相似离度、相似系数、相关系数及最优相似系数可分别考虑两个场之间的形状和强度、空间分布及变化趋势,能找到较相似的场,可供业务参考。通过将不同指标检索到的相似环境场的演变对热带气旋(Tropical Cyclone,TC)路径的影响量引入到TC路径预报中,检验其业务应用效果,发现单纯移向的预报效果好于路径预报,路径预报中相似离度的效果稍好于其他方法,而移向预报中最优系数法最好。另通过相似环境场检索,能找到由相似环境场所对应的相似历史TC,并依据不同度量性指标得到一个历史相似TC集,为台风业务、科研提供参考。     

基于相似离度的相似预报系统

相似高度法是短期气候预测中常用的预报方法之一，该方法能够同时考虑环流场之间在形态和数值两方面的相似情况，是一种比较全面客观的相似衡量标准。依据相似离度的原理，利用可视化编程工具Visual Basic 6.0，开发了分析500hPa高度场相似离度并结合本地资料进行降水量预报的业务系统。     

相似离度法在逐日降水概率预报中的应用

考虑环流的演变特征，设计一种环流演变相似离度预报方法，利用1991－2001年的EMCWF24－144h的格点资料，分别提取3个物理意义清晰、又具有立体性和多元性的相似因子，依据最小离度相似原理，进行相似离度过滤，从历史样本中选出与预报形势演变场最相似的样本，对照济南市及其周边五县（区）各站的降水情况，预测出各站未来1－6d的逐日降水概率。     

相似预报技术在数值预报产品中的释用

利用ＥＣＭＷＦ三层数值预报产品,综合相似系数和距离系数两种相似预报方法,建立了既能反映环流间形相似又能反映值相似的相似离度天气预报系统。     

全国各省市气象科技期刊文摘⑦

1相似离度在山东省冰雹预报逐级指导技术中的应用 　　《山东气象》 2000年第 4期 张丰启 　　威海市气象局 264200　　摘要 应用 1986～ 1995年 4～ 6月逐日 00UTC、 12UTC高空常规气象资料和山东省各县 4～ 6月的冰雹灾害资料，分析了山东省 4～ 6月冰雹天气的环流背景特征。根据低涡型冰雹和非低涡型冰雹的动力、热力差异，制作了低涡型与非低涡型冰雹的预报指标。利用相似离度描述两个物理量场的相似程度，并制作了山东省分县冰雹预报逐级指导的相似预报方法。试验证明方法实用性强，应用效果较好。整个预报过程实现了全客观化和全自…     

相似离度在入型判别和定时、定点、定量预报中的应用

应用1986－1997年的常规探空资料，用相似离度制作了威海市冰雹强对流天气定时、定点、定量的概率预报方法。根据合成的威海市冰雹的四种环流型的数值信息，用相似离度实现了预报场的入型判别，应用HLAFS某时刻预报产品和多级相似方法实现威海市冰雹的多时次，定时、定点，定量、客观自动化概率预报。     

用500hPa环流相似作兴安盟夏季降水量预报

计算兴安盟夏季降水量与前期 5 0 0 h Pa月平均高度相关系数场 ,分析其相关关键区 ,筛选出一批相关系数值较高的关键区域作为预报因子 ,根据预报年因子与样本年因子的接近程度 ,作相似离度计算 ,以相似离度度量 ,进行选相似作预报。从而得出夏季雨量预报。在 2 0 0 1年夏季短期气候预测中应用 ,效果非常好     

一种台风路径相似检索的算法研究

台风路径可视为二维平面上的一段曲线，根据两条台风路径曲线的相似离度可以判断其数值相似和形态相似的程度。由于直接应用台风基本资料进行相似离度计算有一定的难度和局限性，需要研究利用相似离度原理判断两条台风路径曲线相似程度的计算方法。按照设计的算法处理台风基本资料，可以确定两条台风路径曲线上的对应控制点，得到两条曲线对应控制点之间的距离和距离偏差的方向，最终只需在一个方向计算相似离度就能直接分析两条曲线的相似性。对相似台风进行检索的实例表明，该算法是可行的，能够从台风基本资料库中检索出与当前台风路径最相似的台风个例。     

A quantitative method for estimating Pasquill stability class from windspeed and sensible heat flux density

A simple exponential expression, based upon a form of the Kazanski-Monin stability parameter, modified to account explicitly for effects of surface roughness, and semi-empirically derived from both qualitative and quantitative observations, is presented that relates windspeed and sensible heat flux density to Pasquill stability class. The method, though simple in mathematical form, gives results consistent with physical intuition and reproduces, quantitatively, the essential features of previously published nomograms with an added capability for treating all stability classes and any surface roughness from 0.10 to 100 cm. For the stable classes, a new expression for the wind profile stability factor, predicted by similarity theory, is introduced that produces results more consistent than the more common linear form.     

大气边界层的研究——从均匀到非均匀

主要从理论、试验角度对大气边界层的研究进行了简要的回顾,尤其对近年来倍受关注的非均匀地表条件下的边界层研究进行了较详细的介绍,并对大气边界层的研究进行了展望。20世纪50年代,Monin和Obukhov提出的Monin-Obukhov相似理论,为现代大气边界层物理学奠定了基础。之后进行的多次大型综合性外场试验,不仅揭示和发现了大气边界层中的许多现象和规律,也验证和发展了Monin-Obukhov相似理论。80年代以后,非均匀地表条件下的大气边界层研究越来越受到关注,一些新的现象被揭示,新的问题被提出,同时也提出了一些新的概念和研究方法。未来10 a,除大气湍流机理等需长期坚持研究外,还应进一步开展非均匀复杂下垫面边界层研究、城市边界层研究和局地边界层气象预报研究。     

Improvement to the Evaporation Duct Model by Introducing Nonlinear Similarity Functions in Stable Conditions

Modified refractivity (M) profile is an important parameter to describe the atmospheric refraction environment, as well as a key factor in uniquely evaluating electromagnetic propagation effects. In order to improve the model-derived M profile in stable (especially very stable) conditions, three nonlinear similarity functions, namely BH91, CB05, SHEBA07, are introduced in this paper to improve the original Babin_V25 model, and the performances of these modified models are verified based on the hydrometeorological observations from tower platforms, which are finally compared with the original Babin_V25 model and Local_HYQ92 model. Results show that introducing nonlinear similarity functions can significantly improve the model-derived M profile; especially, the newly developed SHEBA07 functions manage to reduce the predicted root mean square (rms) differences of M and M slope (for both 0–5 m and 5–40 m) by 64.5%, 16.6%, and 60.4%, respectively in stable conditions. Unfortunately, this improved method reacts little on the evaporation duct height; in contrast, Local_HYQ92 model is capable of reducing the predicted rms differences of M, M slope (for both 0–5 m and 5–40 m), and evaporation duct height by 76.7%, 40.2%, 83.7%, and 58.0% respectively. Finally, a new recommendation is made to apply Local_HYQ92 and Babin_SHEBA07 in very stable conditions considering that M slope is more important than evaporation duct height and absolute M value in uniquely determining electromagnetic propagation effects.     

稳定层结条件下非线性相似函数对蒸发波导模型的改进

大气修正折射指数(M)廓线是描述大气折射环境的重要参数,也是评估电波传播的关键因子。为了提高稳定特别是强稳定层结条件下模型预测M廓线的效果,引入三种非线性无量纲相似函数BH91、CB05、SHEBA07对原始的Babin_V25模型进行了改进,并利用铁塔平台实测气象水文数据对改进后的模型预测效果进行了评估,同时将其与改进前的Babin_V25模型以及Local_HYQ92模型的效果进行比较。结果表明:引入非线性相似函数能明显改进模型预测M廓线的效果,尤其是最新发展的SHEBA07,改进后的Babin_SHEBA07模型能在稳定层结条件下预测M值、0~5 m及5~40 m内的M梯度均方根误差分别减少64.5%、16.6%和60.4%,但这种方法对蒸发波导高度的预测效果改进不明显;而基于局地相似理论的Local_HYQ92模型则能使稳定层结条件下M值、0~5 m内、5~40 m内的M梯度以及蒸发波导高度d的预测均方根误差分别减少76.7%、40.2%、83.7%和58.0%。考虑到在电磁波传播特性的评估中,M梯度比蒸发波导高度和M值本身更为重要,最终推荐在强稳定层结条件下选用Local_HYQ92模型和Babin...     

Classification of the stratified atmospheric boundary layers at Molve (Croatia) based on the similarity theory

Summary The stability parameter μ is suggested as the one which is determinable with satisfying accuracy for routine application by means of commonly accessible meteorological data at the Molve location (Croatia). The similarity functions applied for vertical wind speed simulation in the planetary boundary layer (PBL) at Molve were useful for the determination of local stability classes. Universal similarity functions were applied for unstable and neutral stability, whereas local similarity functions were established for stable stratification. Wind speed simulations were performed using two types of wind models. The Monin-Obukhov similarity theory was included in both types. However, it turned out that for the operative determination of the stability of the 35 m deep lowest layer, the stability parameter μ was locally a better stability parameter than the Monin-Obukhov parameter z/L. That was possibly because 35 m deep lowest layer sometimes (depending upon stability) includes a large proportion of the Ekman layer and parameter μ is originally designed for the deeper part of PBL than z/L that is originally designed for the surface layer. At Molve, the input data for local wind models as well as for the stability parameter μ were wind speed at 35 m and temperature at 2 and 35 m above the ground.     

使用遗传算法优化雷达测量降水Z-R关系

将遗传算法应用到雷达测量降水的Z-R关系参数优化问题中,通过引入改进的误差函数加入总降水量误差控制,对1998年6月28日~7月2日阜阳地区的两次降水过程进行了参数优化试验,并和常规的最小二乘法、最优化方法及M-P参数法进行了对比,试验结果表明:新方法在总降水量估测方面具有更高的准确性和更好的动态适应性。     

PARAMETERISING SUB-GRID SCALE VERTICAL TRANSPORT IN ATMOSPHERIC MODELS UNDER STATICALLY STABLE CONDITIONS

Five different formulations of the stability functions used forvertical turbulent transfer in atmospheric models are compared in a 1-Dmodel of the nocturnal boundary layer. One of them has a critical valueof the Richardson number around 0.2 and leads to the traditional log-linear profile, while other more empirical formulations maintain sometransfer at values of Ri around 1.0. Although no new observationalevidence is presented, it is suggested that the latter formulations aremore appropriate for use in atmospheric models because the unresolvedvariability inside a model grid box induces some turbulent transfer evenat super-critical values of the mean Ri. The study shows that themagnitude of the stability functions is principally important in theeffective range of Ri values found in the stable boundary layer and thattheir slopes near the origin are less important. This permits the use inatmospheric models of a simple explicit function of Ri containing asingle parameter, with results similar to those obtained with earlier morecomplex formulations. The results of the simulation with the 1-D model are used toexamine the errors introduced by the relatively thick surface layers of most atmospheric models, in which, for the stable case, the traditionalassumption of constancy of the fluxes with height is often clearlyviolated. When a height variation of the fluxes is introduced in surface-layer formulations, the error in the magnitude of the surface fluxes isdecreased with some of the formulations but not all of them. This lackof sensitivity is explained by a compensation mechanism in which theassumed decrease of the fluxes with height implies a correspondingdecrease of the Obukhov length which acts in the oppositedirection, reducing, and sometimes eliminating, the adverse effect of theunrealistic specification of the fluxes. It may be argued that thiscompensation mechanism also explains the wide range of validity of theMoini-Obukhov similarity theory.     

Retrieval of Atmospheric and Oceanic Parameters and the Relevant Numerical Calculation

It is well known that retrieval of parameters is usually ill-posed and highly nonlinear, so parameter retrieval problems are very difficult. There are still many important theoretical issues under research, although great success has been achieved in data assimilation in meteorology and oceanography. This paper reviews the recent research on parameter retrieval, especially that of the authors. First, some concepts and issues of parameter retrieval are introduced and the state-of-the-art parameter retrieval technology in meteorology and oceanography is reviewed briefly, and then atmospheric and oceanic parameters are retrieved using the variational data assimilation method combined with the regularization techniques in four examples： retrieval of the vertical eddy diffusion coefficient; of the turbulivity of the atmospheric boundary layer; of wind from Doppler radar data, and of the physical process parameters. Model parameter retrieval with global and local observations is also introduced.     

检验全球数值预报模式的相似度等指标

本文依照泛函形式并考虑了球面经纬网格的特点,定义了用于全球数值模式效果检验的指标:距离、距平相似度和倾向相似度,给出了相应的计算方法,并以全球WRF模式为例,检验了该模式的中期预报效果。所得结论如下:指标距离、距平相似度和倾向相似度物理意义明确,易于理论分析,考虑了球面经纬网格的特点,检验准确度高,具有普适性,能方便应用于球面经纬网格输出的数值模式检验。指标距离、距平相似度的检验结果分别与传统检验指标均方根误差、距平相关系数相一致,该指标还可直接用于向量场(如风场)的整体检验。本文的全球WRF模式所做的检验表明,对本文个例,该模式的全球500 hPa中期天气形势预报在第7 d及之内皆可用,5 d及之内预报效果更佳。