共查询到19条相似文献，搜索用时 156 毫秒
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利用高分辨率大气模式WRF（Weather Research Forecast）耦合了简单的海洋混合层模式,设计了不同海洋初始混合层厚度条件下的数值试验,研究了不同混合层厚度对热带气旋（TC）结构和强度的影响。结果表明,当TC经过海洋混合层厚度较浅海域时,TC对应的海洋底层的冷水更易上翻,最冷中心区出现在TC大风中心右... 相似文献
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复杂地形对对流混合层的影响 总被引：2，自引：1，他引：1
用发展后的混合层模式研究下垫面（地形和地面热力）的不均匀性对混合层结构的影响。数值实验表明,在保持了混合层模式简便和实用等特点的同时,发展后的混合层模式能够很好地反映复杂地形对混合层厚度和风速的影响。 相似文献
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本文主要进行了两部分工作；１．利用一套描述混合对流层平均状况的控制方程模拟混合层要素随时间的演变过程。对混合层高度的模拟，采用能量学方法，通过把在混合层顶的能量损耗五混合层内对流和机械湍流动能的产生联系起来，和到混合层顶热通量的参数化表达式，从而使模式方程产合。考虑了影响混合层演浮力，风切变及下沉等因子，并探索一种适合于数值天气预报模式的边界参数化方案。 相似文献
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利用中尺度模式作辽宁省空气污染气象条件预报 总被引：7，自引：2，他引：7
利用非静力中尺度数值模式（MM5V2），试验预报辽宁省空气污染气象条件。在模式中着重加密近地面的垂直分层，使用中期数值预报模式（T106L19）预报场作为初值背景场和侧边界。采用美国污染潜势预报方法，在模式预报输出市场中，通过对近地面层的混合层高度和混合层平均风速的判定，预测未来空气污染气象条件，并用SO2实测值进行检验。 相似文献
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本文总结了本专题自１９９１年正式开展工作以来，围绕着专题的中心内容所做的研究工作结果。着重点放在有地形数值模式的改进和完善以及数值模拟试验这两个方面在模式的改进和完善方面，又着重介绍模式区域的拓宽，土壤下垫面的引入，海洋混合层模式和海洋表层流模式的建立和应用。在数值模拟试验方面，则主要介绍气压梯度力的新算法－“误差扣除法”及其模拟检验，包络地形试验，地形与大气湿过程对夏季风气候特征影响的试验，沙漠 相似文献
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在原球圈范围的P－σ坐标模式中，加入了O3和海洋混合层的作用，对7月中、低纬流场作数值模拟试验，并进行了对比分析。结果表明，O3和海温混合层对夏季环流的影响是重要的。考虑了O3和海洋混合层作用，其模拟结果更接近实况。指出，在天气、气候预报中，有必要考虑Q3和海温异常的影响。 相似文献
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本文总结了本专题自1991年正式开展工作以来，围绕着专题的中心内容所做的研究工作结果。着重点放在有地形数值模式的改进和完善以及数值模拟试验这两个方面在模式的改进和完善方面，又着重介绍模式区域的拓宽、土壤下垫面的引入、海洋混合层模式和海洋表层流模式的建立和应用。在数值模拟试验方面，则主要介绍气压梯度力的新算法──“误差扣除法”及其模拟检验、包络地形试验、地形与大气湿过程对夏季风气候特征影响的试验、沙漠初始湿度对气候变化的影响试验、下垫面在气候变化中的作用试验以及海温异常的影响试验。没有在本文中介绍的数值试验结果，可参看本文集中作者等的其它论文。 相似文献
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大气混合层高度的模式计算和分析 总被引：3，自引：1，他引：2
设计了一套描述混合对流层平均状况的平板模式．模拟了混合层平均要素随时间的演变过程。采用能量学方法,通过考虑影响混合层演变的浮力、风切变及下沉等因子,对混合层高度随时间变化的过程进行数值模拟计算,并与实际观测资料比较。结果表明．模式可以较好地应用于实际业务预报中,同时改进了模式的计算方法．分析了各种物理参数对混合层高度变化的不同影响和物理成因。 相似文献
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In this paper,mixed layer height and certain mean elements are predicted by using a dry mixed layer model.Their variation with time and some basic properties are discussed.The model is tested with the 1967 Australian Wangara experimental data.Comparison of the calculated results with the observed data is conducted.The aim of this paper is to build a predictive model describing the basic properties of the mixed layer and attempts to formulate a boundary layer parameterization scheme suitable for the numerical weather prediction model. 相似文献
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Based on turbulence theory,a 1.5-order closure turbulence model is established.The model incorporating with theground surface energy budget equation is constructed by means of a vertical one-dimensional(1-D)40-levelgrid-mesh.The numerical results reveal the 24-h evolution of the clear planetary boundary layer comparing with theWangara boundary layer data of days 33—34.The model also takes into account some physical processes of radiativetransfer and baroclinicity,revealing some important characteristics observed in the boundary layer,especially for theevolution of the mixed layer and low-level jet.The calculated results are in good agreement with the observational data.On the other hand,we also run the high-resolution model of the planetary boundary layer in the Mesoscale Model Ver-sion 4(MM4)with the same physical processes and initial conditions.The results show that the high-resolution modelcan not reveal those important characteristics as the 1.5-order closure model did.In general,it is shown that the 1.5-or-der closure turbulence model based on turbulence theory is better in rationality and reality. 相似文献
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Application of sodar sounding to atmospheric dispersion—Mixing depth and concentration at the ground
It is the intent of this paper to illustrate how to apply acoustic radar data on the variation of mixing depth in the study of atmospheric dispersion. The box model, as an example of the routine usage of acoustic sounding, has been modified. A case of the development of the structure of mixed layer, resulting from some synoptic process is discussed and the results show that the ordinary model calculations regarding atmospheric dispersion will mislead the assessment of air quality if no remote techniques, such as the acoustic radar, are associated with. 相似文献
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OBSERVING RESULTS OF THE ATMOSPHERIC MIXED LAYER IN BEIJING AREA AND THE EVALUATION OF THEORETICAL MODELS 
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下载免费PDF全文 In the present study the data of wind and temperature profiles and sensible heat flux observed in Beijing inJuly and December of 1986,together with the results of water tank experiments for comparison,are used to testthe prediction models of the atmospheric mixed layer with zero order and first order assumption,respectively.The results show that the entrainment rates in summer and winter used in the zero order model are 0.15 and0.10,respectively,while its value in the first order model ranges between 0.15 and 0.19 with a lower rateat the initial stage of mixed layer development.Emphasis in the study is also placed on the relationship between the entrainmert rate and the developmentof the mixed layer. 相似文献
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采用850毫巴和地面的大尺度天气状况和物理特性作为外参数,将大气边界层下层的地表层进行特殊处理,考虑了层结的作用,其上分成等距15层,考虑地转民随高度线性变化。上下层耦合,建立一个定常平衡初值模型,并将所得的初值作为第一级近似,再利用地面、300、600、900、1500米五个高度测风资料进行动力调整,试图建立一个更加接近实际状态的边界层初值。 文中利用所建立的模型,对大气边界层的一些物理参数的作用进行了分析,并对动力调整过程以及垂直分层的选取等作了讨论。 最后例举华北地区1966年8月23日08时边界层的各层次风场和垂直运动,清楚地显示出边界层内的细致结构。 相似文献
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Joseph P. pandolfo 《Boundary-Layer Meteorology》1971,1(3):277-289
The basic numerical air-sea boundary-layer model described in Pandolfo (1969a, b) was varied to produce a set of models with differing atmospheric boundary-layer formulas, four of which are discussed here. Model I is the basic model itself, with stability and sea-state dependent eddy viscosity, conductivity and diffusivity which may, in certain ranges ofRi, be unequal. This model is applied on a relatively fine grid. Model II, applied on the same grid, uses formulas which yield equal eddy conductivity, diffusivity, and viscosity. The calculated eddy coefficients depend only on the height and wind shear. Model III uses the same exchange coefficient formulas as Model II. However, the surface-layer eddy flux in Model III is calculated by assuming that logarithmic profiles of the transported variables are present in this layer. Model IV is the same as Model III in these respects, but employs a relatively coarse vertical grid. This model, therefore, includes boundary layer formulas most like those conventionally used in large scale atmospheric models (e.g. Miyakoda, 1969).The four models were integrated numerically with identical inputs of initial, boundary, and auxiliary data prepared from observations made over the eastern half of the BOMEX observational area during June 21–25, 1969.Models I and IV are, in general, in better agreement with each other than either is with Model II. This is true for the model-generated upper and lower boundary fluxes of mean momentum and latent heat; and for the internal boundary layer production of mean kinetic energy by the cross-isobaric flow component. Model I agrees, on balance, about as well with Model IV as does Model III. The solutions for Models I, III, and IV are also, in general, more consistent with observed data, viz. 5-day average temperature profiles in the layer from the surface to 1000 meters, and 5-day averages of sea surface temperature and of surface-layer atmospheric humidity. Solutions for Model I are in better overall agreement with the observed data, and with the average observed surface-layer wind.The results show that, under the limitations implicit in these preliminary experiments, accurate simulations of observed data are possible with boundary-layer formulas of the type used in Model IV, and even more accurate simulation with the modest refinements represented by Model I. Piecemeal imposition of such refinements could, however, lead to models, like Model II, with significantly different energetic properties and less simulative accuracy. Specifically, the results support the speculation (Miyakodaet al., 1969) that the shallowness of the simulated Trades noted in some large-scale models is due to deficiencies in the boundary-layer eddy stress formulations used. 相似文献
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In this paper, a second-order model is proposed for the study of the evolution of the nocturnal boundary layer (NBL). The model is tested against the Wangara data on atmospheric boundary layer. The computer results show ihat the model can simulate some important characters observed in the NBL, and that a kind of sudden change may occur in the developing process of NBL. 相似文献
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An efficient, pianetary boundary layer (PBL) model is developed and validated with empirical data for applications in general circulation models (GCMs). The purpose of this PBL model is to establish the turbulent surface fluxes as a function of the principal external PBL parameters in a numerically efficient way. It consists of a surface layer and a mixed layer matched together with the conditions of constant momentum and heat flux at the interface. An algebraic solution to the mean momentum equations describes the mixed-layer velocity profile and thus determines the surface wind vector. The velocity profile is globally valid by incorporating the effect of variable Coriolis force without becoming singular at the equator. Turbulent diffusion depends on atmospheric stability and is modeled in the surface layer by a drag law and with first-order closure in the mixed layer. Radiative cooling in the stably stratified PBL is considered in a simple manner. The coupled system is solved by an iterative method. In order to preserve the computational efficiency of the large-scale model, the PBL model is implemented into the GISS GCM by means of look-up tables with the bulk PBL Richardson number, PBL depth, neutral drag coefficient, and latitude as independent variables.A validation of the PBL model with observed data in the form of Rossby number similarity theory shows that the internal feedback mechanisms are represented correctly. The model, however, underpredicted the sensible heat-flux. A subsequent correction in the turbulence parameterization yields better agreement with the empirical data. The behavior of the principal internal PBL quantities is presented for a range of thermal stabilities and latitudes. 相似文献