共查询到20条相似文献，搜索用时 187 毫秒
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本文从统计物理学角度分析了气象学基本问题。指出气象学中的大气微团等元量可与统计物理中的基本研究对象粒子相对应。因而统计物理中的概念、方法和规律可以移植到气象学中来。文中定义了大气分布函数和大气的H函数,还研究了大气能量分布律和大气熵。文中综述了熵极值原理在气象上的应用并提出大气熵守恒猜想。最后指出如这一猜想被证实,则可以使中短期的数值天气预告的准确率明显提高。 相似文献
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国内外生态气象现状及其发展趋势 总被引：3，自引：0，他引：3
首先探讨了生态学、气象学与生态气象学的发展历程,并给出了目前常见的几种生态气象学的定义;其次,对国内外生态气象学的现状进行了简单分析,主要介绍了国际上开展的与生态系统有关的许多观测计划和研究试验,以及国内不同部门开展的陆地生态系统观测状况,并分析了我国气象部门生态气象业务服务现状及存在的问题;再次,分析了生态气象学未来的发展趋势。 相似文献
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国内外生态气象现状及其发展趋势 总被引：2，自引：0，他引：2
首先探讨了生态学、气象学与生态气象学的发展历程,并给出了目前常见的几种生态气象学的定义;其次,对国内外生态气象学的现状进行了简单分析,主要介绍了国际上开展的与生态系统有关的许多观测计划和研究试验,以及国内不同部门开展的陆地生态系统观测状况,并分析了我国气象部门生态气象业务服务现状及存在的问题;再次,分析了生态气象学未来的发展趋势. 相似文献
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相对分布函数和气象熵 总被引：9，自引：1，他引：9
针对某变量在一个物质系统中的分布状况,本文提出了相对分布函数的概念。文中论证了它与概率密度分布函数的等价性、列举了一些相对分布函数实例。由于熵与概率分布的已知关系和后者与相对分布函数等价,作者给出了计算气象要素场的熵值的方法。文中认为开展熵气象学研究可以为气象学找出新的出路。 相似文献
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大气边界层气象学研究综述 总被引：5，自引：2，他引：5
文中回顾了大气边界层气象学的发展历史，总结了目前大气边界层气象学的主要进展，并指出国内外在未来大气边界层气象学研究方面面临的一些主要科学问题，以及对未来大气边界层气象学的发展方向提出若干建议，同时还指出了大气边界层气象学在思想上和方法上应该注意的一些相关问题。 相似文献
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下垫面的非均匀性影响地气通量观测的准确性和代表性,青藏高原复杂下垫面通量印痕分布的研究对地气相互作用的观测、模拟及其天气气候影响均具有重要意义。印痕分析是研究通量观测信息空间代表性的重要方法,通量印痕模型FFP(Flux Footprint Prediction)为计算通量印痕提供了一种行之有效的方法。基于西藏珠穆朗玛大气过程与环境变化国家野外科学观测研究站、阿里荒漠环境综合观测研究站、西藏纳木错高寒湖泊与环境国家野外科学观测研究站、慕士塔格西风带环境综合观测研究站和藏东南高山环境综合观测研究站5个台站2013年观测数据,利用FFP模型对通量印痕进行了模型参数敏感性分析,探讨了不同站点通量印痕分布的时空特点、具体影响因素,进而对观测台站架设提供指导。研究结果表明,通量印痕的主要影响因素为观测高度、风速、风向,下垫面类型为常绿针叶林的林芝站对观测高度、行星边界层高度较其他台站敏感。在青藏高原,使用三维超声风速仪观测数据得到的通量印痕的空间尺度为250～500 m。5个台站中珠峰站白天稳定层结时次最少,占白天数据点的15.69%,阿里站夜间不稳定层结时次最少,占夜间数据点的13.32%。在... 相似文献
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罗伯特·菲茨罗伊(Robert FitzRoy,1805—1865)是英国著名的气象学家。作为天气预报业务的创始人,首次创造了"天气预报"这一气象专用术语,于1863年撰写的《The weather book(天气学手册)》深入浅出地介绍了其在气象学研究方面的多年研究成果,是一本可以让大众阅读的气象学实用指南。文中简要介绍了菲茨罗伊的人生经历,并以菲茨罗伊的代表作《天气学手册》为重点,梳理了菲茨罗伊在气象学方面的研究成果,重点介绍了菲茨罗伊在气象仪器、全球气候特征、天气预报等方面的认识,并围绕菲茨罗伊的科学研究成果浅谈了其对气象学的主要贡献。 相似文献
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非均匀下垫面湍流通量观测的印痕分析 总被引：5，自引：1，他引：4
利用2005年在北京昌平区小汤山开展的非均匀下垫面观测实验的观测数据,分别处理了涡旋相关法和大孔径闪烁仪LAS测得的感热通量,并运用印痕模型对数据进行“源区”分析。分析结果表明:在复杂地表上,涡旋相关的测量值由于混杂了其他下垫面的通量信息,不能真实地反映其观测区域的湍流特征,存在着观测误差。而LAS观测出现的低估问题则与掺混高度和“源区”有关。通过用印痕方法进行数据订正后,以上问题均得到很好的改善,订正结果与LAS观测通量的线性关系良好,两者的相关系数达到0.9。实验结果验证了印痕模型在非均匀下垫面的适用性。 相似文献
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介绍了环境气象生活指数的概念,指出环境气象生活指数的开发主要是运用气象学、天气学、统计学、经济学等理论和业务技术方法,采用现场观测、实验研究、理论分析等手段,依赖基本气象业务系统,探讨气象条件对人们的生活、国民经济各个部门的作用和影响机理。建立南宁生活指数预报系统的主要技术方法,包括引用他人已经建立的预报模型、参照中国气象局文件建立预报模型、统计分析建立预报模型、经验预报模型也在文中进行了详细介绍。文章指出南宁生活指数预报系统要求的最低环境为586/133,16M内存,120M硬件空间;建立在W indow s 9X/NT/2K/XP操作系统上,开发工具为V isua l B as ic60;系统主要包括三个模块为数据录入模块、预报结论修改模块、参数设置模块;系统的预报流程和使用步骤也进行了介绍。文章还通过对部分指数的预报准确率分析评估了系统预报效果,评估表明系统预报总体效果良好。最后文章讨论了进一步完善系统的设想。 相似文献
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A Three-Dimensional Backward Lagrangian Footprint Model For A Wide Range Of Boundary-Layer Stratifications 总被引：5，自引：3，他引：5
We present a three-dimensional Lagrangian footprint model with the ability to predict the area of influence (footprint) of a measurement within a wide range of boundary-layer stratifications and receptor heights. The model approach uses stochastic backward trajectories of particles and satisfies the well-mixed condition in inhomogeneous turbulence for continuous transitions from stable to convective stratification. We introduce a spin-up procedure of the model and a statistical treatment of particle touchdowns which leads to a significant reduction of CPU time compared to conventional footprint modelling approaches. A comparison with other footprint models (of the analytical and Lagrangian type) suggests that the present backward Lagrangian model provides valid footprint predictions under any stratification and, moreover, for applications that reach across different similarity scaling domains (e.g., surface layer to mixed layer, for use in connection with aircraft measurements or with observations on high towers). 相似文献
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L. M. Reithmaier M. Göckede T. Markkanen A. Knohl G. Churkina C. Rebmann N. Buchmann T. Foken 《Theoretical and Applied Climatology》2006,84(4):219-233
Summary Long-term flux measurement sites are often characterized by a heterogeneous terrain, which disagrees with the fundamental
theoretical assumptions for eddy-covariance measurements. An evaluation procedure to assess the influence of terrain heterogeneity
on the data quality has been developed by G?ckede et al. (2004), which combines existing quality assessment tools for flux
measurements with analytic footprint modeling. In addition to micrometeorological input data, this approach requires information
defining the land use structure and the roughness of the surrounding terrain.
The aim of this study was to improve the footprint based site evaluation approach by using high-resolution land use maps derived
by Landsat ETM+ and ASTER satellite data. The influence of the grid resolution of the maps on the results was examined, and
four different roughness length classification schemes were tested. Due to numerical instabilities of the analytic footprint
routine, as an additional footprint model a Lagrangian stochastic footprint routine (Rannik et al., 2003) was employed. Application
of the approach on two German FLUXNET sites revealed only weak influence of the characteristics of the land use data when
the land use structure was homogeneous. For a more heterogeneous site, use of the more detailed land use maps derived by remote
sensing methods resulted in distinct differences indicating the potential of remote sensing for improving the flux measurement
site evaluation. 相似文献
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A Simple Parameterisation for Flux Footprint Predictions 总被引：9，自引：6，他引：9
Flux footprint functions estimate the location and relative importance of passive scalar sources influencing flux measurements
at a given receptor height. These footprint estimates strongly vary in size, depending on receptor height, atmospheric stability,
and surface roughness. Reliable footprint calculations from, e.g., Lagrangian stochastic models or large-eddy simulations
are computationally expensive and cannot readily be computed for long-term observational programs. To facilitate more accessible
footprint estimates, a scaling procedure is introduced for flux footprint functions over a range of stratifications from convective
to stable, and receptor heights ranging from near the surface to the middle of the boundary layer. It is shown that, when
applying this scaling procedure, footprint estimates collapse to an ensemble of similar curves. A simple parameterisation
for the scaled footprint estimates is presented. This parameterisation accounts for the influence of the roughness length
on the footprint and allows for a quick but precise algebraic footprint estimation. 相似文献
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We compare flux and concentration footprint estimates of athree-dimensional Lagrangian stochastic dispersion modelapplying backward trajectories with the results of ananalytical footprint model by Kormann and Meixner.The comparison is performed for varying stability regimesof the surface layer as well as for different measurementheights. In general, excellent correspondence is found. 相似文献
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利用2006年5～6月和2007年5～6月中国科学院HEST大气科学实验在珠峰绒布寺河谷野外观测期间获得的观测资料,分析了珠峰地区河谷近地层风向、风速、温度、湿度和CO2的日变化特征,讨论了珠峰北坡冰川风和山谷风的特点以及高原地表辐射、地表反照率和近地层湍流通量的变化特征.结果表明:在复杂地形和特殊下垫面影响下,珠峰绒布河谷地区近地面层各个气象要素和湍流通量日变化特征显著,并且明显存在冰川风和山谷风复合的局地环流,冰川风对该地区地气间物质能量交换起着重要作用. 相似文献
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Turbulent flux observations and modelling over a shallow lake and a wet grassland in the Nam Co basin,Tibetan Plateau 总被引：2，自引：1，他引：1
The Tibetan Plateau plays an important role in the global water cycle and is strongly influenced by climate change. While energy and matter fluxes have been more intensely studied over land surfaces, a large proportion of lakes have either been neglected or parameterised with simple bulk approaches. Therefore, turbulent fluxes were measured over wet grassland and a shallow lake with a single eddy-covariance complex at the shoreline in the Nam Co basin in summer 2009. Footprint analysis was used to split observations according to the underlying surface, and two sophisticated surface models were utilised to derive gap-free time series. Results were then compared with observations and simulations from a nearby eddy-covariance station over dry grassland, yielding pronounced differences. Observations and footprint integrated simulations compared well, even for situations with flux contributions including grassland and lake. The accessibility problem for EC measurements on lakes can be overcome by combining standard meteorological measurements at the shoreline with model simulations, only requiring representative estimates of lake surface temperature. 相似文献
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影响测风塔代表性的因素很多,为了合理地确定测风塔观测结果能够代表的区域范围,需要通过适当的方法综合考虑这些因素。湍流通量代表性研究中常用的印痕函数是风速、稳定度、下垫面粗糙度等的函数,可以定量地刻画单点观测结果的代表性。利用印痕函数方法对中国风能资源观测网中来自不同下垫面的44个测风塔2010年的观测结果进行了测风塔资料的代表性分析。首先,根据两层(10、70 m)的风速和温度计算稳定度参数Lp并确定中性层结,粗糙度的计算选取了中性层结条件下满足对数风廓线的资料。然后,利用中性层结下70 m高度主导风向和风向频率较大方位的资料分析了两种印痕函数方法(Schuepp和Hsieh方法)的适用性及代表性范围与粗糙度的关系。两种方法得到的印痕函数对应距离(即代表性范围)比较接近。但是,在复杂山地Schuepp方法已不适用。当粗糙度小于10 m时,粗糙度与印痕函数对应距离的关系可用对数-线性函数描述。根据经验推荐了利用印痕函数积分90%对应的距离以及下垫面显著变化位置来确定测风塔代表范围。但是,印痕函数积分阈值仍需要通过示踪实验或数值模拟检验。 相似文献
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非均匀网格的过渡湍流理论及其在大气边界层数值模拟中的应用 总被引：1，自引：1，他引：1
本文将Stull提出的均匀网格下的过渡湍流理论推广到非均匀网格情形，推广的非均匀网格的过渡湍流理论满足Stull提出的对过渡矩阵系数的要求并具有清晰的物理意义。然后，将非均匀网格的过渡湍流理论应用于一维大气边界层数值模式中，对Wangara资料进行了模拟，并与均匀网格情形进行了对比。计算表明，非均匀网格的过渡湍流模式能很好地模拟Wangara大气边界层平均量与湍流量的变化；本文非均匀网格的过渡湍流理论的推广是可行的，它可能会在大气边界层数值模拟及其他方面（如：中尺度模式）得到应用。 相似文献
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Important questions concerning the turbulent exchange of atmospheric pollutants between the air and natural surfaces urgently require answers, but sensors for many important species are not yet sufficiently well developed for use with standard micrometeorological methods. There is need, therefore, to develop methods by which deficient sensors can be used in micrometeorological applications. There is also need to extend micrometeorological methods to circumstances which do not satisfy the conventional perfect-site constraints. Here, methods based upon the assumption of cospectral similarity are explored. Initial tests indicate that it is possible to estimate daytime turbulent fluxes with sensors giving response times considerably greater than the values normally quoted for eddy correlation (e.g., 5 s instead of 1 s), and to compute first-order corrections for the error resulting from the lack of detection of high-frequency turbulence. It is suggested that a similar method might be used to derive flux data in terrain more complex than can be handled by conventional micrometeorology. The techniques outlined here should be applied only with caution, but appear adequate to permit the use of deficient sensors in some circumstances, and good sensors over some micrometeorologically deficient terrain. 相似文献