共查询到18条相似文献，搜索用时 109 毫秒
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针对城市下垫面条件进行合理的参数设置,将城市影响引入辐射雾模式,并结合NCEP/ CFSv2(Climate Forecaset System Verison2)资料及常规气象观测资料,对2010年2月8日发生在上海宝山的一次辐射雾过程进行数值研究。结果表明:(1) 受城市地表影响,感热输送成为城市地表加热大气的主要方式;城市下垫面的湍流交换作用较强,近地面湍流交换系数最大可达2.0 m2/s;(2) 城市辐射雾的起雾高度比农村高,雾首先在32 m高度上形成,且雾顶可发展到150 m高度;上部雾形成的主要原因是长波辐射冷却引起的水汽凝结;而8 m以下气层雾形成的主要原因是重力沉降导致的含水量的累积。 相似文献
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重庆雾的二维非定常数值模拟 总被引：26，自引：5，他引：21
重庆是著名的“雾都”.本文建立了一个复杂地形下详细考虑长波辐射冷却、地表热量平衡、雾水沉降、水汽凝结和蒸发、湍流交换系数等的二维非定常雾模式,以实测资料为初始场,研究了一次重庆雾的形成和发展过程.对江河、热岛、辐射、地形和山城的影响,模式分别进行了数值试验. 相似文献
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本文利用美国国家大气研究中心(NCAR)和宾夕法尼亚州立大学联合研制的第5代中尺度气象模式系统MM5对珠江三角洲地区夏季出现的一次辐射雾过程进行了数值模拟研究。模拟的结果在辐射雾出现的时间以及辐射雾的高度方面都与实况十分相近。我们对辐射雾的形成机制也进行了分析和数值试验．结果表明．地面的长波辐射冷却促使辐射雾形成．而短波辐射的加热是辐射雾消散的主要原因。另外．增加模式的垂直分辨率以及改变珠江三角洲地区的下垫面类型都可以使模式模拟的辐射雾的结果有明显的改善。 相似文献
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辐射雾中振荡现象的数值研究 总被引：1，自引：0，他引：1
本文利用一维二阶矩闭合边界层土壤藕合模式模拟了夜间边界层中辐射雾的形成、发展和消亡过程。结果表明:湍流场和辐射场的相互作用对辐射雾的形成和发展有重要的影响。雾中液态水含量以及一些特征参量呈现准周期振荡变化，这种振荡和雾中湍涡的涨落有关。模拟结果和观测基本符合。 相似文献
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北京地区一次辐射雾的数值模拟 总被引：6，自引：2，他引：4
利用非静力中尺度模式MM5V3对2006年11月20日北京地区的一次大雾天气过程进行了数值研究。模拟结果与极轨卫星监测图像以及十二通道微波辐射计观测资料的对比表明,模式对此次雾的模拟是比较成功的,尤其是在雾区的分布位置、雾的高度以及雾的维持时间等方面。针对不同的云物理方案、长波辐射项、短波辐射项以及模式的垂直分辨率进行了4组敏感性实验。结果表明,地面的长波辐射冷却促使辐射雾的形成,而短波辐射的加热是辐射雾消散的主要原因。另外,增加模式的垂直分辨率以及选取更加详细的云微物理方案可以使模式模拟的辐射雾的结果有明显的改善。 相似文献
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建立了一个二维时变数值模式,模拟了浅水湖沼—陆面地区平流辐射雾形成、演变和消散的基本过程。结果表明,地面温度迅速下降是成雾前的一个重要特征;浅水湖沼地区充沛的水汽对平流辐射雾的形成极为有利;平流作用可使辐射雾呈爆发性发展;长短波辐射与湍流混合的共同作用是辐射雾生消的主要物理机制;成雾后在雾顶的稍下方有长波辐射冷却率的极大区,最大值为２１×１０－３ｏＣ／ｓ（７６ｏＣ／ｈ）。模拟结果与观测事实基本一致。 相似文献
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本文采用二阶矩湍流闭合方案，分别就非静力和准静力两种条件建立ＰＢＬ数值模式，并模拟了二维山脊流场的结构，计算了二维山体对气流平均场和湍流场的影响。计算结果表明，无论是平均场还是湍流场，采用准静力假设都会造成模拟结果的较大偏差，且对平均场的影响比对湍流场的影响更为显著。两种模式计算结果的差别还随地形坡度和背景风增大而增大。 相似文献
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Zhou Binbin 《Acta Meteorologica Sinica》1988,2(2):223-233
The formation and development of radiation fog are studied by using a one-dimensional model.Theresults are as follows:(1)The fog can change the ambient wind and temperature fields,on the contrary,theambient fields may also influence the fog;(2)The modeling fog forms initially at a certain level above thesurface,which is detailedly explained in the paper;(3)Turbulence delays the formation of fog but promotesits development;(4)Whether fog liquid water content exchange coefficient equals momentum exchangecoefficient has no influence on the numerical results.In addition,wind,temperature,exchange coefficient,and net radiative flux before and after the formation of radiation fog,are also studied. 相似文献
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为了比较不同长、短波辐射参数化方案对江苏省大雾过程的模拟效果,本文利用WRF模式,通过设计不同长、短波辐射参数化方案,对江苏省2015年5月18—21日和12月20—21日2次典型大雾过程进行了数值模拟,讨论了模式中不同长、短波辐射参数化方案对江苏省大雾过程的模拟影响。采用平均绝对误差(MAR)、均方根误差(RMSE)、皮尔逊相关系数(r)及中国气象局颁布的雾区预报规定,评价得到不同条件的最优模拟方案。结果表明:(1)热力条件与水汽条件,模拟最优方案为长波GFDL方案与短波RRTMG方案组合。(2)动力条件,最优辐射参数化方案组合为CAM方案与FLG方案组合。(3)雾区的模拟,效果最好的方案为长波GFDL方案与短波RRTMG方案的组合。 相似文献
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Martina Tudor 《Meteorology and Atmospheric Physics》2010,108(1-2):57-70
Fog and low stratus forecasting experiments have been carried out with the numerical weather prediction model ALADIN on a case of long lasting fog. The model has been used with different radiation, cloud diagnosing and horizontal diffusion schemes, different representation of orography, increased vertical resolution and with or without prognostic condensates and turbulent kinetic energy (TKE). Some of the numerical set-ups are able to reproduce the fog (low stratus) field as seen in the satellite images as well as the measured 2m temperature and relative humidity diurnal cycles. The results show that cloud diagnosing schemes and overlap assumptions play a more important role than a more sophisticated radiation scheme, or introduction of prognostic cloud water, ice, rain, snow or TKE. More realistic orography representation and a more physical horizontal diffusion scheme significantly improve the modelled low stratus and 2m temperature in the areas with variable orography. 相似文献
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利用地面观测资料、秒级探空资料结合WRF中尺度数值模式,对2016年6月25—26日江苏南部地区一次影响范围广、持续时间长的罕见辐射雾过程进行了数值模拟分析。结果表明:(1)雾区范围和气象要素数值模拟结果与实况基本一致;(2)低层超薄超强逆温为此次夏季雾的形成、发展和维持提供了稳定条件;(3)成雾前江苏南部地区白天出现的降水是夜间浓雾形成的重要水汽来源;(4)夜间地表辐射冷却作用是浓雾形成的重要因素;地面风速稳定低于2 m·s^-1,有利于浓雾的维持;日出后随着短波辐射增强风速增大、稳定层结破坏促使浓雾减弱消散。 相似文献
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MP-3000A 是一种新型大气探测仪器,可以连续得到从地面到10 km 高度上高分辨率的位温、相对湿度、水汽密度及其廓线。选取大雾发生、维持及消散时微波辐射计观测数据,分析发现,大雾从形成到消散过程中水汽密度、相对湿度和位温均有不同变化;大雾发生前近地层大气中的相对湿度、水气密度一般会稳定增加,大雾发生时两者会有爆发性增加的现象。大雾维持阶段在近地层多伴有逆温层,辐射雾逆温层明显;大雾期间雾层高度有稳定型也有波动型,雾层高度下降时大雾会迅速加强。大雾消散时近地层大湿区减小抬升,水汽密度迅速减小。因此研究微波辐射计探测的大气水汽密度、液态水含量和位温,将有助于提高大雾生成与消散的预报、预警。 相似文献
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Edward H. Barker 《Boundary-Layer Meteorology》1977,11(3):267-294
A two-dimensional boundary-layer model is described. The model is designed to predict and study the effects of meteorological changes on the formation and dissipation of fog and stratus. Radiational heat loss along with the transport of static energy, moisture and momentum are treated. Cloud droplet distributions are parameterized using a gamma distribution from which radiative properties and droplet fall velocities are computed. Turbulent exchange coefficients are calculated using the Monin-Obukhov theory of similitude which accounts for variations in atmospheric stability. Although the boundary-layer depth depends only on turbulent intensity during stable atmospheric conditions, its growth during unstable conditions is determined from the capping inversion's intensity and the amount of turbulence generated at the surface.Several experiments are presented which demonstrate the effects of various meteorological parameters on the formation and duration of stratus and fog. Energy-budget analyses show the importance of each of the physical processes being modeled.Although not new, radiative transfer processes are shown to be extremely important in the transfer of heat from the boundary layer and in the process of fog formation. Fog formation location is highly sensitive to the moisture content upstream, whereas changes in wind speed had much less effect in the variance of fog location.Numerical experiments with other processes such as back radiation from the atmosphere, haze and cloud droplet population, are described and shown to have smaller effects. 相似文献
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P. Cereceda P. Osses H. Larrain M. Farías M. Lagos R. Pinto R. S. Schemenauer 《Atmospheric Research》2002,64(1-4)
A project in northern Chile was undertaken to determine the origin and behaviour of fog in the coastal and inland locations of the Tarapacá Region. In the Pampa del Tamarugal, 50 km from the sea, conditions exist for the formation of radiation fog. Advective fog has been studied on the coast and orographic fog was observed at a few coastal sites near mountain ranges with elevations above 1000 m. Fog water collected by two standard fog collectors (SFC) for 3 1/2 years showed an average flux of 8.5 l m−2 day−1 on the coast and 1.1 l m−2 day−1 inland 12 km from the coastline. On only a few days in 10 months was water collected at the inland site of Pampa del Tamarugal. GOES satellite images are shown to illustrate the pattern of formation of the stratocumuli cloud over the sea, its approach to the coastline, the entrance of fog by corridors through the coastal range and the presence of radiation fog inland. The results are important for the understanding of fog formation and dissipation along the coastal mountain range and for the recognition of potential sites for the installation of fog water collectors, which can be used as a water source in the Atacama Desert. The results also provide vital information for use in the preservation of the unique ecosystems of the most arid desert of the world. 相似文献
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A satellite-based climatology of fog and low-level stratus in Germany and adjacent areas 总被引：1，自引：0，他引：1
Jrg Bendix 《Atmospheric Research》2002,64(1-4)
A 10-year fog climatology of Germany and adjacent areas, based on NOAA-Advanced Very High-Resolution Radiometer (AVHRR) data, is presented. Maximum fog frequency is obtained for the Lake Constance area; minimum fog occurrence, accounting for basins and river valleys, is located in the Lower Rhine area. This is a transition zone between coastal advection fog and the more continental radiation fog of the lower mountain range. Fog persistence is estimated by a comparison of night and day maps. Using the bispectral approach of Nakajima and Nakajima [J. Atmos. Sci. 52, (1995) 4043], the potential of weather satellite data for climatologies of fog's optical and microphysical properties is examined. Maps of fog optical depth, effective radius and liquid water path (LWP) are computed from well-illuminated noon images and the resulting data set is statistically evaluated. Typical features of advection fog are obtained for the coastal areas of the North and Baltic Seas, while the fog of the pre-Alpine basins reveals characteristics of continental radiation fog. The results are in general accordance with field observations of various sources. 相似文献