一次飑线过程的云微物理参数化方案数值试验及其成因分析   总被引：2，自引：1，他引：1  

许广  费建芳  黄小刚  姜勇强  程小平 《气象科学》2017,37(3):283-292

利用WRF模式6种适合高分辨率且包含多种固态水成物粒子的云微物理参数化方案,分别对2012年5月16日江苏北部一次飑线过程进行数值试验,结果表明:LIN方案模拟的飑线回波反射率、强降水TS评分、结构和强度等均要优于其余5种微物理参数化方案。分析不同参数化试验结果中不同水成物粒子占比随时间的变化特征,并针对LIN方案采取敏感性试验和水成物转化微物理过程分析指出,在此次飑线过程中的各水成物粒子中,霰/雹粒子占比最大,是降水过程中最重要的粒子;地面降水直接来源是雨水,雨水主要来源于中层霰/雹粒子的融化,小部分来源于云水的自动转化;中层霰/雹粒子最主要来源是通过雨霰转化过程中的雨水撞冻冰雹微物理过程,其次是霰撞冻云水的微物理过程,而冰相物质雪晶和云冰的碰并、撞冻和自动转化过程微乎其微。  相似文献   

The Scaling Behaviour of a Turbulent Kinetic Energy Closure Model for Stably Stratified Conditions   总被引：2，自引：1，他引：1  

Peter Baas  Stephan R. de Roode  Geert Lenderink 《Boundary-Layer Meteorology》2008,127(1):17-36

We investigate the scaling behaviour of a turbulent kinetic energy (TKE) closure model for stably stratified conditions. The mixing length scale for stable stratification is proportional to the ratio of the square root of the TKE and the local Brunt–Väisälä frequency, which is a commonly applied formulation. We analyze the scaling behaviour of our model in terms of traditional Monin–Obukov Similarity Theory and local scaling. From the model equations, we derive expressions for the stable limit behaviour of the flux–gradient relations and other scaling quantities. It turns out that the scaling behaviour depends on only a few model parameters and that the results obey local scaling theory. The analytical findings are illustrated with model simulations for the second GABLS intercomparison study. We also investigate solutions for the case in which an empirical correction function is used to express the eddy diffusivity for momentum as a function of the Richardson number (i.e. an increasing turbulent Prandtl number with stability). In this case, it seems that for certain parameter combinations the model cannot generate a steady-state solution. At the same time, its scaling behaviour becomes unrealistic. This shows that the inclusion of empirical correction functions may have large and undesired consequences for the model behaviour.  相似文献   

不同模式分辨率和物理过程方案对贵州降水影响的对比试验   总被引：1，自引：0，他引：1  

伍红雨  陈静 《高原气象》2008,27(6)

利用MM5中尺度数值模式,在20,15和10 km模式分辨率下,采用相同的方案对贵州两次大暴雨过程进行数值模拟试验。然后选用KUO、GRELL、KAIN-FRITSCH和BETTS-MILLER(以下简称KU、GR、KF和BM)4种对流参数化方案,分别在MRF和Blackadar 2种边界层参数化方案下,对贵州汛期16个降水个例进行数值模拟试验,对模拟结果进行对比分析并与实况资料进行比较,结果表明:预报的降水落区对参数化方案敏感。随着分辨率的提高,降水分布与实况更接近。MM5模式的这4种积云参数化方案对环流的模拟较好,但模拟降水的效果有差别:对50 mm以下的降水,GR方案的预报效果较好,KF方案则较差;对50 mm以上的降水,BM、KF方案的预报效果一般较好;选择MRF或Blackadar的边界层参数化方案对降水预报效果区别不大。选择BM或KF积云对流参数化方案、混合相显式水汽方案、MRF边界层参数化方案和云辐射方案的组合,取得了优于其他组合的预报结果。  相似文献   

城市下垫面空气动力学参数确定方法综述   总被引：1，自引：0，他引：1       下载免费PDF全文

胡张保  俞炳丰 《气象与环境学报》2008,24(5)

地表粗糙度和零平面位移是2个重要的空气动力学参数,对于城市下垫面,粗糙元的形态非常复杂,空间分布上存在较大的非均匀性,如何确定城市下垫面地表粗糙度和零平面位移目前尚无最佳方案。概述了这2个参数适用于城市非均匀下垫面的参数化方法,包括风温观测方法和粗糙元形态学方法。探讨了各自在应用过程中存在的问题及进一步的研究工作,并且提出,通过数学模型的改进和卫星遥感技术的引入,粗糙元形态学方法会有更好的发展前景：  相似文献   

Assessing eddy heat flux and its parameterization: A wavenumber perspective from a 1/10° ocean simulation     

Alexa Griesel  Sarah T. Gille  Janet Sprintall  Julie L. McClean  Mathew E. Maltrud 《Ocean Modelling》2009,29(4):248-260

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陆面过程模式中积雪过程的参数化及初步试验     

严中伟  季劲钧 《高原气象》1995,14(4):415-424

为了用气候模式研究冰雪圈变化的气候效应，我们在已经发展的土壤－植被－大气模式基础上，考虑积雪改变表水文和反照率的参数化，建立了包含雪盖问题的陆面过程模式。利用中国西北黑河地区的ＨＥＩＦＥ实测气象和辐射资料，检验了模式对大气降雨和降雪的响应，结果表明，该模式描写的各种物理过程合理，一些可观测要素（如地面温度和地表净辐射通量）的演变特征与实况相当一致。  相似文献   

改进的Kuo-Type积云对流参数化方案   总被引：1，自引：1，他引：1  

刘金良  汪钟兴 《热带气象学报》1994,10(2):185-192

通过对热力学方程和水汽方程两端作计算的对比，指出Ｋｕｏ－Ｔｙｐｅ参数化方案的一种改进型Ｋｒｉｓｈｎａｍｕｒｔｉ回归方案在长江中下游地区应用的不足之处，同时结合本地区的积层云共存及相互作用的事实，以实用性为目的，提出一种改进的Ｋｕｏ－Ｔｙｐｅ参数化方案。它具有以下特点：积云对流发生的判据具有区域特点；采用Ｋｒｉｓｈｎａｍｕｒｔｉ的具有明确物理意义的对流参数，但不从统计回归中求得，而是直接由“实时资料  相似文献   

Quantifying uncertainty in changes in extreme event frequency in response to doubled CO2 using a large ensemble of GCM simulations   总被引：2，自引：1，他引：2  

David N. Barnett  Simon J. Brown  James M. Murphy  David M. H. Sexton  Mark J. Webb 《Climate Dynamics》2006,26(5):489-511

We discuss equilibrium changes in daily extreme surface air temperature and precipitation events in response to doubled atmospheric CO₂, simulated in an ensemble of 53 versions of HadSM3, consisting of the HadAM3 atmospheric general circulation model (GCM) coupled to a mixed layer ocean. By virtue of its size and design, the ensemble, which samples uncertainty arising from the parameterisation of atmospheric physical processes and the effects of natural variability, provides a first opportunity to quantify the robustness of predictions of changes in extremes obtained from GCM simulations. Changes in extremes are quantified by calculating the frequency of exceedance of a fixed threshold in the 2 × CO₂ simulation relative to the 1 × CO₂ simulation. The ensemble-mean value of this relative frequency provides a best estimate of the expected change while the range of values across the ensemble provides a measure of the associated uncertainty. For example, when the extreme threshold is defined as the 99th percentile of the 1 × CO₂ distribution, the global-mean ensemble-mean relative frequency of extremely warm days is found to be 20 in January, and 28 in July, implying that events occurring on one day per hundred under present day conditions would typically occur on 20–30 days per hundred under 2 × CO₂ conditons. However the ensemble range in the relative frequency is of similar magnitude to the ensemble-mean value, indicating considerable uncertainty in the magnitude of the increase. The relative frequencies in response to doubled CO₂ become smaller as the threshold used to define the extreme event is reduced. For one variable (July maximum daily temperature) we investigate this simulated variation with threshold, showing that it can be quite well reproduced by assuming the response to doubling CO₂ to be characterised simply as a uniform shift of a Gaussian distribution. Nevertheless, doubling CO₂ does lead to changes in the shape of the daily distributions for both temperature and precipitation, but the effect of these changes on the relative frequency of extreme events is generally larger for precipitation. For example, around one-fifth of the globe exhibits ensemble-mean decreases in time-averaged precipitation accompanied by increases in the frequency of extremely wet days. The ensemble range of changes in precipitation extremes (relative to the ensemble mean of the changes) is typically larger than for temperature extremes, indicating greater uncertainty in the precipitation changes. In the global average, extremely wet days are predicted to become twice as common under 2 × CO₂ conditions. We also consider changes in extreme seasons, finding that simulated increases in the frequency of extremely warm or wet seasons under 2 × CO₂ are almost everywhere greater than the corresponding increase in daily extremes. The smaller increases in the frequency of daily extremes is explained by the influence of day-to-day weather variability which inflates the variance of daily distributions compared to their seasonal counterparts.  相似文献   

三维冰雹云催化数值模式   总被引：89，自引：10，他引：79  

洪延超 《气象学报》1998,56(6):641-653

为了研究冰雹形成机制、催化防雹机制和通过数值试验获得冰雹云优化催化技术,在以前工作的基础上,发展了一个３维弹性冰雹云催化数值模式。模式考虑了冰雹云中详细的微物理过程,各种粒子采用双变参数谱,将云中水物质分成水汽、云水、雨水、冰晶、雪、霰、冻滴和雹８类,可以预报粒子的比浓度和比含量,尤其可以计算以霰或冻滴为胚胎的雹块的数量,非常适合研究冰雹的形成机制。此外,建立了催化剂ＡｇＩ的守恒方程,考虑了人工冰核的凝华核化及与云、雨滴接触的冻结核化过程,并用地面降雹动能通量检验催化防雹效果,因此,也可以研究催化防雹机制和对雹云的催化技术。  相似文献   

混合云在GCM气候模拟中的重要性   总被引：1，自引：1，他引：1       下载免费PDF全文

孙治安 Shine.  K 《应用气象学报》1996,7(4):452-459

文章提出了一种简单且适用于大气环流模式（GCM）的冰云辐射参数化。利用该参数化和UGAMP大气环流模式研究了混合云在GCM气候模拟中的重要性。结果表明，云的相态变化及其所产生的反馈作用对模拟的气候状态有显著的影响。在高纬地区，云的相态变化可使地气系统净辐射增加。而在热带则使净辐射减少。  相似文献