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建立了一个三维时变、考虑风切变的烟团轨迹模式,模拟复杂气流系统中污染物散布的特征,对污染物散布的日变化进行了实例模拟。结果表明：模式能较好地反映了气象场日变化对污染物扩散的影响,揭示地面浓度分布规律,模拟结果与一些观测事实合理地一致。 相似文献
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利用城市大气污染数值预报系统CAPPS的第三版(CAPPS3),经过安装、调试和本地化、自动化处理,建立起适合于辽宁的区域空气质量数值预报系统,用于预报辽宁的城市污染指数和等级以及各污染物的日均浓度分布.通过模式预报结果与监测资料的对比,发现辽宁14个主要城市SO2、NO2预报准确率的总体水平明显高于PM10.区域污染物浓度分布位置和大小的预报结果与实际情况相符,污染物小时浓度的演变也与实际风场的变化趋势保持一致,表明CAPPS3模式系统能够及时准确地预报出区域污染的形成和发展过程. 相似文献
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本文运用随机游动模拟方法改进建立一种粒子—烟团模式，成功地模拟了对流边界层条件下污染物扩散，粒子—烟团模式的模拟结果与水槽试验的结果吻合较好。数值模拟试验结果表明粒子—烟团模式能在施放粒子数较少，从而运行时间很短的情况下，得到优于一般随机游动模式的模拟性能。用KNRC的资料对模式的模拟性能作一验证，表明模式也能很好地模拟实际大气中不同稳定度情况下的扩散。 相似文献
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选取2016年12月17—22日青岛一次典型重污染天气,利用大气污染物监测结果、地面气象要素观测资料和欧洲中期天气预报中心（ECMWF）ERA5再分析数据对此次过程中大气污染物及气象场的变化特征进行分析。观测分析表明此次污染过程持续时间长达5 d以上,其中19—21日为重污染天气（PM 2.5 日均质量浓度ρ>150 μg·m-3）。根据气象场和PM2.5质量浓度变化特征,此次污染过程可分为3个阶段：17日02时—19日08时为青岛污染物累积阶段,研究区受西南风控制,PM2.5质量浓度逐渐上升,700 hPa等压面上高空槽的维持及槽前持续的南风、西南风有利于污染物累积,同时近地面相对湿度增加,是此次持续性重污染天气形成的重要条件;19日09时—20日20时为青岛污染维持加剧阶段,相对湿度大、风速很小,污染物扩散条件差,PM2.5质量浓度最高;20日21时—22日08时为青岛污染消散阶段,青岛对流层中下层及地面风速均增大并产生弱降水,有利于污染物扩散稀释和湿清除,PM2.5质量浓度逐渐降低。WRF-Chem数值模式能够较好地模拟出主要气象要素和青岛PM2.5 质量浓度的变化特征,模拟结果表明山东省内污染物排放贡献了青岛PM2.5的49.5%;污染物跨省输送对此次污染事件也有重要贡献,其中来自研究区以南的安徽和江苏的排放对青岛PM2.5的贡献率可达25.5%。 相似文献
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本文运用随机游动模拟方法改进建立一种粒子－－烟团模式，成功地模拟了对流边界层条件下污染物扩散，粒子－－烟团模式的模拟结果与水槽试验的结果吻合较好。数值模拟试验结果表明粒子－－烟团模式能在旋放粒子数较少，从而运行时间很短的情况下，得到优于一般随机游动模式的模拟性能。用ＫＮＲＣ的资料对模拟性能作一验证，表明模式也能很好地模拟实际大气中不同稳定度情况下的扩散。 相似文献
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以济源市“十一五”期间的大气环境质量监测数据为依据,首先对济源市主要大气污染物的年均和季均浓度进行了分析,然后运用综合污染指数法和Spearman秩相关系数法对大气污染程度的变化趋势进行了分析,并把“十一五”末与“十五”末的大气污染物综合污染指数进行了对比。结果表明,“十一五”期间大气环境质量总体上保持基本稳定并有所好转,但也存在一定程度的污染,特别是冬季污染程度明显高于其他季节,二氧化硫仍是首要污染物。最后,提出了进一步改善大气环境质量的对策和建议。 相似文献
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Umberto Rizza Massimo Cassiani Umberto Giostra Cristina Mangia 《Boundary-Layer Meteorology》2000,95(2):319-339
An advanced model aimed at describing the problem of dispersion in theconvective boundary layer is proposed. The pollutant particles are groupedin clusters and modelled as Gaussian puffs. The expansion of each puff ismodelled according to the concept of relative dispersion and expressed interms of the spectral properties of the energy containing eddies of the turbulent field. The centre of mass of each puff is moved along a stochastic trajectory, obtained using a Lagrangian stochastic model and filtering the velocity with a recursive Kalman filter. At any instant, a filtering procedure, depending both on travel time and on puff size, acts to select spectral components involved in the expansion and in the meandering of the puff. Such an approach requires only a moderate number of puff releases, so that the proposed model is faster to run than a standard Lagrangian model. On the other hand, unlike the traditional puff model, it allows us to simulate both expansion and meandering of the puff. Therefore, it is well suited to simulate dispersion when the turbulent structures are larger thanthe plume dimensions, as for example in convective conditions. Being based onspectral formulations in both Eulerian and Lagrangian parts, the model is consistent in all the turbulent parameterizations utilised. Comparisons with a standard Lagrangian particle model as well as with a classical convective experimental dataset show good performance of the proposed model. 相似文献
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SCIPUFF模式的简化及验证 总被引：1，自引：0，他引：1
将SCIPUFF（Second-order Closure Integrated PUFF)模式中烟团分解和合并的思想予以保留，而对其与二阶矩有关的扩散参数则予以简化，用Briggs公式给出扩散参数。开发出合并与分解的烟团模式（Splitting-Merging Puff)，简称SMP模式，通过与SCIPUFF模式结果相比较，SMP模式对计算精度影响不大，与Monte-Carlo方法相比较，两者模拟结果较接近，但计算效率至少可以提高一个数量级，SMP模式在预报的准确性和时效性方面都能满足开展空气质量预报的要求。 相似文献
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Xiaoying Cao Gilles Roy William J. Hurley William S. Andrews 《Boundary-Layer Meteorology》2011,139(3):487-500
The Gaussian distribution is a good approximation for transient (instantaneously released) puff concentration distributions
within a short period of time after release. Artificial neural network (ANN) models for puff dispersion coefficients were
developed, based on observations from field experiments covering a wide range of meteorological conditions (in March, May,
August and November). Their average predictions were in very good agreement with measurements, having high correlation coefficients
(r > 0.99). A non-linear multi-variable regression model for dispersion coefficients was also developed, under the assumption
that puff dispersion coefficients increase with time, and follow power laws. Both ANN-based and multi-regression non-linear
models were able to use easily measured atmospheric parameters directly, without the necessity of predefining the Pasquill
stability category. Predictions of ANN-based and multi-regression-based Gaussian puff models were compared with those of Gaussian
puff models using Slade’s dispersion coefficients and COMBIC, a sophisticated model based on Gaussian distributions. Predictions
from our two new models showed better agreement with concentration measurements than the other Gaussian puff models, by having
a much higher fraction within a factor of two of measured values, and lower normalized mean square errors. 相似文献
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利用中尺度气象模式模拟了特殊地形下的气象变化特征,通过CALPUFF模拟了大气环境风险事件的精细化扩散特征。结果表明：西宁市地面风特征与河谷地形走向基本一致,典型风场表现为湟水河谷盛行西北和东南风,北川河谷则多为偏北风。由于青藏高原昼间强烈的山坡辐射增热和致使低空出现逆温层频率高,强度大,不利于污染物在垂直方向的扩散,河谷剖面模拟温度场的结果显示等高度山坡附近比河谷中心的温度大约高1.5℃。CALPUFF烟团轨迹模式能较好地应用于西宁市大气环境风险事件的模拟研究,模拟结果能清楚描绘出污染物沿河谷输送与扩散的初始状况和细致分布,同时在复杂地形和气象条件影响下出现山体对烟团的阻碍效应、烟团因流场在山脊处出现形变以及山谷风环流影响等非定常扩散现象,扩散轨迹符合复杂地形和气象条件影响的特征和规律,模拟结果对准确预估大气环境风险事件在复杂地形和气象条件下城市中的扩散特征、影响范围和程度具有重要意义。 相似文献
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本文描述了基于PIC方法的三维大气扩散粒子分裂(ADPS)模式,并用解析解和1988年的广州地区现场观测资料验证了本模式.模式根据局地均匀和定常假设引入大粒子概念、烟团扩散原理和大粒子分裂技术,并运用了嵌套网格.ADPS模式用于模拟气态污染物在大气中的散布,同时也具备模拟TSP扩散的效能. 相似文献
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M. G. Hadfield 《Boundary-Layer Meteorology》1994,69(4):417-448
We examine vertical and horizontal diffusion of a passive scalar puff from a surface point source in a convective boundary layer (CBL). Numerical results are presented from a large-eddy simulation (LES) with embedded subgrid Lagrangian particle simulation (LPS). There is good agreement in most respects with previous laboratory and numerical studies. Analytical approximations for the concentration, horizontal flux and vertical flux are found to work reasonably well; they are based on the assumption that the concentration follows a Gaussian function in the horizontal and vertical, and that the dimensionless width and height scales of the puff follow simple functions of time. Fluxes and concentration gradients are related through a continuity relationship, without the need for an eddy diffusivity assumption. The instantaneous, point-source fields can be integrated for any source geometry. We compare predictions from the LES/LPS model for a sinusoidal surface flux with previous results from an LES with sinusoidal buoyancy flux and confirm that the buoyancy perturbations diffuse like a passive scalar. We also consider a continuous point source and derive footprint functions for vertical flux measurements above the surface layer. 相似文献