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1.
将中国气象科学研究院（CAMS）混合双参数云微物理方案用于中尺度天气模式WRF,开展了对2013年超强台风天兔（1319）的模拟,通过与台风最佳路径、强度及热带降雨测量卫星（TRMM）资料对比,分析CAMS云微物理方案在模拟台风中的适用性及云微物理过程对模拟台风天兔的影响机制。设计了3组敏感性试验:修改雪粒子质量和落速系数（EXP1）,采用海洋性云滴参数（EXP2）,同时修改雪粒子质量和落速系数并采用海洋性云滴参数（EXP3）。结果表明:EXP1和EXP3由于霰碰并雪速率的增加及减小的雪下落通量,导致雪含量显著降低,同时也减少了整体冰相物的含量;EXP2和EXP3模拟的台风眼区对流有效位能快速减小,再现了前期台风的快速增强过程,路径偏差也最小;各试验模拟的小时降水率总体偏强,EXP3的降水空间分布与实况更接近,明显降低雪粒子含量,并一定程度上改善模拟的台风路径、强度及降水分布等。该结果不但可为改进适用于台风的云微物理参数化方案提供思路,也可加深云微物理过程对台风影响的认识。  相似文献   

2.
The Chinese Academy of Meteorological Sciences (CAMS) two-moment bulk microphysics scheme was adopted in this study to investigate the representation of cloud and precipitation processes under different environmental conditions.The scheme predicts the mixing ratio of water vapor as well as the mixing ratios and number concentrations of cloud droplets,rain,ice,snow,and graupel.A new parameterization approach to simulate heterogeneous droplet activation was developed in this scheme.Furthermore,the improved CAMS scheme was coupled with the Weather Research and Forecasting model (WRF v3.1),which made it possible to simulate the microphysics of clouds and precipitation as well as the cloud-aerosol interactions in selected atmospheric condition.The rain event occurring on 27-28 December 2008 in eastern China was simulated using the CAMS scheme and three sophisticated microphysics schemes in the WRF model.Results showed that the simulated 36-h accumulated precipitations were generally agreed with observation data,and the CAMS scheme performed well in the southern area of the nested domain.The radar reflectivity,the averaged precipitation intensity,and the hydrometeor mixing ratios simulated by the CAMS scheme were generally consistent with those from other microphysics schemes.The hydrometeor number concentrations simulated by the CAMS scheme were also close to the experiential values in stratus clouds.The model results suggest that the CAMS scheme performs reasonably well in describing the microphysics of clouds and precipitation in the mesoscale WRF model.  相似文献   

3.
A large number of in-situ measurements of cloud-precipitation microphysical properties have been made since 1960, including measurements of particle size distribution, particle concentration, and liquid water content of clouds and rain. These measurements have contributed to considerable progress in understanding microphysical processes in clouds and precipitation and significant improvements in parameterizations of cloud microphysics in numerical models. This work reviews key findings regarding cloud-precipitation microphysics over China. The total number concentrations of various particles vary significantly, with certain characteristic spatial scales. The size distributions of cloud droplets in stratiform clouds can generally be fit with gamma distributions, but the fit parameters cover a wide range. Raindrop size distributions(RSDs)associated with stratiform clouds can be fit with either exponential or gamma distributions, while RSDs associated with convective or mixed stratiform-cumuliform clouds are best fit with gamma distributions.Concentrations of ice nuclei(IN) over China are higher than those observed over other regions, and increase exponentially as temperature decreases. The particle size distributions of ice crystals, snow crystals, and hailstones sampled at a variety of locations can be reliably approximated by using exponential distributions,while aerosol particle size distributions are best described as the sum of a modified gamma distribution and a Junge power-law distribution. These results are helpful for evaluating and improving the fidelity of physical processes and hydrometeor fields simulated by microphysical parameterizations. The comprehensive summary and analysis of previous work presented here also provide useful guidelines for the design of future observational programs.  相似文献   

4.
1960年以来东亚季风区云-降水微物理的直接观测研究   总被引：1，自引：0，他引：1  
云-降水的直接观测结果是云微物理参数化的重要依据。自1960年以来,处于东亚季风影响下的中国实施了大量对云-降水微物理参数的观测和研究,旨在加深对云-降水微物理过程的认识,从而改进数值模式中云微物理参数化方案和指导人工影响天气作业。云-降水微物理参数包括气溶胶、冰核、云滴、雨滴、冰晶、雪晶、冰雹等粒子浓度和谱分布,以及云滴、雨滴含水量等。中国已有云-降水微物理参数的成果可归纳为:(1)通常云-降水微物理粒子浓度变化较大,但总体变化有一定的范围;(2)采用Γ函数拟合云滴谱更接近实际谱,但不同拟合谱参数差异较大;(3)可用指数函数和Γ函数来拟合层状云降水雨滴谱,Γ函数拟合积云和层积混合云降水雨滴谱精度更高;(4)中国冰核浓度较高,冰核浓度随温度的降低近似成指数变化;(5)冰晶谱、雪晶谱、冰雹谱通常采用指数函数来描述;(6)通常使用荣格(Junge)和Γ函数来分段描述气溶胶粒子谱拟合误差更小。由于云-降水过程及其反馈作用描述不准确是数值模式预报结果不确定性的最大因素,中国正在不断地推进云降水的微物理观测研究,以期进一步加深对东亚季风区云-降水微物理特征的认识,从而为模式中微物理参数化方案的改进提供观测依据和科学指导。基于数值预报模式中云微物理过程参数化发展的需要,总结了中国1960年以来云-降水微物理直接观测的研究成果,可为东亚地区云-降水微物理研究及其模式参数化方案的改进提供观测依据。此外,针对云微物理参化发展的需求,结合过去已有的大量观测提出了几点建议,为今后云-降水物理综合性观测方案的设计提供参考。  相似文献   

5.
The impact of different cloud microphysics parameterization schemes on the intensity and structure of the Super-strong Typhoon Rammasun (1409) in 2014 is investigated using the Weather Research and Forecasting model version 3.4 with eight cloud microphysics parameterization schemes. Results indicate that the uncertainty of cloud microphysics schemes results in typhoon forecast uncertainties, which increase with forecast time. Typhoon forecast uncertainty primarily affects intensity predictions, with significant differences in predicted typhoon intensity using the various cloud microphysics schemes. Typhoon forecast uncertainty also affects the predicted typhoon structure. Greater typhoon intensity is accompanied by smaller vortex width, tighter vortex structure, stronger wind in the middle and lower troposphere, greater height of the strong wind region, smaller thickness of the eyewall and the outward extension of the eyewall, and a warmer warm core at upper levels of the eye. The differences among the various cloud microphysics schemes lead to the different amounts and distributions of water vapor and hydrometeors in clouds. Different hydrometeors have different vertical distributions. In the radial direction, the maxima for the various hydrometeors forecast by a single cloud microphysics scheme are collocated with each other and with the center of maximum precipitation. When the hydrometeor concentration is high and hydrometeors exist at lower altitudes, more precipitation often occurs. Both the vertical and horizontal winds are the strongest at the location of maximum precipitation. Results also indicate that typhoon intensities forecast by cloud microphysics schemes containing graupel processes are noticeably greater than those forecast by schemes without graupel processes. Among the eight cloud microphysics schemes investigated, typhoon intensity forecasts using the WRF Single-Moment 6-class and Thompson schemes are the most accurate.  相似文献   

6.
With the Reisner-2 bulk microphysical parameterization of the fifth-generation Pennsylvania State University–U.S. National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5), this paper investigates the microphysical sensitivities of Typhoon Chanchu. Four different microphysical sensitivity experiments were designed with an objective to evaluate their respective impacts in modulating intensity forecasts and microphysics budgets of the typhoon. The set of sensitivity experiments were conducted ...  相似文献   

7.
Representation of cloud microphysical processes is one of the key aspects of numerical models. An improved double-moment bulk cloud microphysics scheme (named IMY) was created based on the standard Milbrandt-Yau (MY) scheme in the Weather Research and Forecasting (WRF) model for the East Asian monsoon region (EAMR). In the IMY scheme, the shape parameters of raindrops, snow particles, and cloud droplet size distributions are variables instead of fixed constants. Specifically, the shape parameters of raindrop and snow size distributions are diagnosed from their respective shape-slope relationships. The shape parameter for the cloud droplet size distribution depends on the total cloud droplet number concentration. In addition, a series of minor improvements involving detailed cloud processes have also been incorporated. The improved scheme was coupled into the WRF model and tested on two heavy rainfall cases over the EAMR. The IMY scheme is shown to reproduce the overall spatial distribution of rainfall and its temporal evolution, evidenced by comparing the modeled results with surface gauge observations. The simulations also successfully capture the cloud features by using satellite and ground-based radar observations as a reference. The IMY has yielded simulation results on the case studies that were comparable, and in ways superior to MY, indicating that the improved scheme shows promise. Although the simulations demonstrated a positive performance evaluation for the IMY scheme, continued experiments are required to further validate the scheme with different weather events.  相似文献   

8.
Dual-polarization(dual-pol)radar can measure additional parameters that provide more microphysical information of precipitation systems than those provided by conventional Doppler radar.The dual-pol parameters have been successfully utilized to investigate precipitation microphysics and improve radar quantitative precipitation estimation(QPE).The recent progress in dual-pol radar research and applications in China is summarized in four aspects.Firstly,the characteristics of several representative dual-pol radars are reviewed.Various approaches have been developed for radar data quality control,including calibration,attenuation correction,calculation of specific differential phase shift,and identification and removal of non-meteorological echoes.Using dual-pol radar measurements,the microphysical characteristics derived from raindrop size distribution retrieval,hydrometeor classification,and QPE is better understood in China.The limited number of studies in China that have sought to use dual-pol radar data to validate the microphysical parameterization and initialization of numerical models and assimilate dual-pol data into numerical models are summarized.The challenges of applying dual-pol data in numerical models and emerging technologies that may make significant impacts on the field of radar meteorology are discussed.  相似文献   

9.
A two-moment bulk stratiform microphysics scheme, including recently developed physically-based droplet activation/ice nucleation parameterizations has been implemented into the Grid-point Atmospheric Model of IAP LASG (GAMIL) as an effort to enhance the model’s capability to simulate aerosol indirect effects. Unlike the previous one-moment cloud microphysics scheme, the new scheme produces a reasonable representation of cloud particle size and number concentration. This scheme captures the observed spatial variations in cloud droplet number concentrations. Simulated ice crystal number concentrations in cirrus clouds qualitatively agree with in situ observations. The longwave and shortwave cloud forcings are in better agreement with observations. Sensitivity tests show that the column cloud droplet number concentrations calculated from two different droplet activation parameterizations are similar. However, ice crystal number concentration in mixed-phased clouds is sensitive to different heterogeneous ice nucleation formulations. The simulation with high ice crystal number concentration in mixed-phase clouds has less liquid water path and weaker cloud forcing. Furthermore, ice crystal number concentration in cirrus clouds is sensitive to different ice nucleation parameterizations. Sensitivity tests also suggest that the impact of pre-existing ice crystals on homogeneous freezing in old clouds should be taken into account.  相似文献   

10.
The improvement of the accuracy of simulated cloud-related variables, such as the cloud fraction, in global climate models (GCMs) is still a challenging problem in climate modeling. In this study, the influence of cloud microphysics schemes (one-moment versus two-moment schemes) and cloud overlap methods (observation-based versus a fixed vertical decorrelation length) on the simulated cloud fraction was assessed in the BCC_AGCM2.0_CUACE/Aero. Compared with the fixed decorrelation length method, the observation-based approach produced a significantly improved cloud fraction both globally and for four representative regions. The utilization of a two-moment cloud microphysics scheme, on the other hand, notably improved the simulated cloud fraction compared with the one-moment scheme; specifically, the relative bias in the global mean total cloud fraction decreased by 42.9%–84.8%. Furthermore, the total cloud fraction bias decreased by 6.6% in the boreal winter (DJF) and 1.64% in the boreal summer (JJA). Cloud radiative forcing globally and in the four regions improved by 0.3%?1.2% and 0.2%?2.0%, respectively. Thus, our results showed that the interaction between clouds and climate through microphysical and radiation processes is a key contributor to simulation uncertainty.  相似文献   

11.
Typhoon KROSA in 2007 is simulated using GRAPES, a mesoscale numerical model, in which a two-parameter mixed-phase microphysics scheme is implanted. A series of numerical experiments are designed to test the sensitivity of landfalling typhoon structure and precipitation to varying cloud microphysics and latent heat release. It is found that typhoon track is sensitive to different microphysical processes and latent heat release. The cloud structures of simulated cyclones can be quite different with that of varying microphysical processes. Graupel particles play an important role in the formation of local heavy rainfall and the maintenance of spiral rainbands. Analysis reveals that the feedback of latent heat to dynamic fields can significantly change the content and distribution of cloud hydrometeors, thus having an impact on surface precipitation.  相似文献   

12.
We performed a modeling study of the cloud processes in a heavy snowfall event occurring in North China on 20–22 December 2004. The nonhydrostatic Mesoscale Model (MM5) was used to carry out experiments with the Reisner-2 explicit microphysical parameterizations in four nested domains to test the sensitivity of simulated heavy snowfall to different snow intercept parameters. Results show that while the different intercept parameters do not significantly affect the accumulated snowfall amounts at the surface in either total amount or location, some microphysical characteristics of the modeled heavy snowfall event are impacted. The budget of cloud microphysics is analyzed to determine the dominant cloud processes. In the control experiment (CTL) with the snow intercept (N os) specified as a function of temperature, the primary simulated hydrometeor is snow, and its mixing ratio is an order of magnitude larger than that of the other cloud species. Relative to CTL, the experiment with a fixed intercept (CON3E6) produced lower snow mixing ratios, more cloud water and graupel mixing ratios. Among the two experiments, while snowfall is slightly smaller in CON3E6, other processes like the rate of graupel fall, condensation and evaporation of cloud water, deposition and sublimation of graupel are all larger in CON3E6 than in CTL. Among CTL, CON3E6, and two more experiments (CON2E7: with a smaller fixed intercept; and NOSQS: N os a function of snow mass mixing ratio), the budget shows that CON3E6 produces the smallest deposition and sublimation of snow, the largest deposition of cloud ice, and the largest conversion from cloud ice to snow.  相似文献   

13.
A set of microphysics equations is scaled based on the convective length and velocity scales.Comparisons are made among the dynamical transport and various microphysical processes.From the scaling analysis,it becomes apparent which parameterized microphysical processes present off-scaled influences in the integration of the set of microphysics equations. The variabilities of the parameterized microphysical processes are also studied using the approach of a controlled parameter space.Given macroscopic dynamic and thermodynamic conditions in different regions of convective storms,it is possible to analyze and compare vertical profiles of these processes.Bulk diabatic heating profiles for a cumulus convective updraft and downdraft are also derived from this analysis. From the two different angles,the scale analysis and the controlled-parameter space approach can both provide an insight into and an understanding of microphysics parameterizations.  相似文献   

14.
The novel model system LM-SPECS is presented combining a spectral bin microphysics scheme and the three-dimensional Lokalmodell (LM, today called COSMO) of the German Weather Service (“Deutscher Wetterdienst”). The model is designed to investigate in detail the interaction of atmospheric aerosol particles, clouds and precipitation. The microphysics scheme includes a combined spectrum of wetted aerosols, cloud droplets and rain drops. As a first application of the model, sensitivity studies on an artificial deep convective cloud were done. The results produced by LM-SPECS are satisfying. The studies show, e.g., that a diminished initial particle number leads to larger cloud droplets and thus to a higher efficiency of coalescence. This results in a larger amount of precipitation. Furthermore, studies on mixed phase clouds show the influence of varying ice nuclei, such as bacteria, kaolinite and soot, on cloud properties. Here, a more effective freezing leads to an increased number of ice particles with smaller radii. The results point to the importance of a detailed knowledge of the underlying microphysical processes in order to understand the formation of clouds and precipitation more accurately. Though to date the model was applied to artificial cases only, the use of the mesoscale weather model allows for more complex realistic cases which are subject to further studies.  相似文献   

15.
In this paper, the evolution of the microphysical characteristics in different regions(eyewall, inner core, and outer rainbands) and different quadrants [downshear left(DL), downshear right(DR), upshear left(UL), and upshear right(UR)]during the final landfall of Typhoon Ewiniar(2018) is analyzed using two-dimensional video disdrometer and S-band polarimetric radar data collected in Guangdong, China. Due to the different types of underlying surfaces, the periods before landfall(mainly dominated ...  相似文献   

16.
数值模式能否准确地对降水过程进行预报,很大程度上取决于云微物理参数化方案能否准确地对云内的物理过程进行描述。目前显式云微物理参数化方案中对粒子的下落速度、不同直径粒子的浓度分布两方面的微物理特征,分别使用质量加权下落末速度和粒子谱进行描述。因此,参数化方案中不同的描述方式直接影响数值模式对降水过程的模拟结果。本文使用耦合了一种新的体积水法双参数云微物理参数化方案的WRF模式（Weather Research and Forecasting Model）3.5.1版本对发生在2013年5月8日的一次华南强降水过程进行模拟,分别对Ferrier和Locatelli两种质量加权下落末速度计算方法,以及常数参数和根据东亚地区实际观测结果改进的谱形参数两种粒子谱形参数设置的模拟结果进行分析,并对他们的四组参数组合预报结果进行评估。结果表明:（1）质量加权末速度的改变对降水强度有一定影响;（2）粒子谱形参数对模拟降水的强度和发展都有明显的影响,且谱形参数对本次降水模拟的影响强于下落末速度的影响;（3）Ferrier质量加权末速度和改进的谱形参数的组合试验组对降水的预报效果,相对其他三组试验有较明显的优势。  相似文献   

17.
陈赛男  郭学良  付丹红 《大气科学》2019,43(6):1344-1364
云物理过程是云和降水形成的重要环节。本文针对2011年6月23日发生在北京地区的一次大暴雨过程进行了云降水与天气特征分析,并开展了WRF模式中10种不同云微物理方案对此次暴雨强度、落区和发生时间的敏感性数值模拟试验。研究结果表明,此次大暴雨是由多单体组织、合并形成深厚的中尺度对流系统,并具有明显的短时局地特征和有利的高低空、高低纬度大中尺度天气环流形势及强烈的水汽输送条件。暴雨强度、落区和发生时间的数值模拟结果对云物理方案非常敏感。不同云物理方案对累积降水量≥50 mm和≥100 mm的暴雨模拟的ETS评分显示,只有Thompson方案对此暴雨量级的评分均为正,其他方案的ETS评分均不理想,特别是对累积降水量≥100 mm的大暴雨模拟。在小时暴雨强度和发生时间方面,Thompson方案模拟效果也较好,其次是Lin方案和WSM6方案;对区域累积最大降水量和落区的模拟方面,Thompson方案和Morrison方案模拟的最大累积降水量更接近观测值,但在落区方面,一些具有完整云物理过程的单参数方案（Lin方案、WSM6方案）模拟效果较好,但模拟的最大降水量偏小。针对暖雨的双参数方案WDM6对区域平均降水模拟较好,但对暴雨极端降水模拟较差。对造成差异的原因分析表明,不同云物理方案的差异主要体现在雪和霰的参数化方面,由于采用的粒子谱分布、密度和末速度不同,导致云中粒子间的碰并和形成过程不同,大部分云物理方案模拟的霰含量高,雪含量低。这种云微物理过程的差异会导致云动力过程的反馈作用出现明显不同,但这种反馈作用的差异主要体现在降水粒子对上升气流的拖曳作用不同。尽管云中相变潜热过程对云动力过程具有很重要的影响,但不同云物理方案在相变潜热过程和温度廓线分布方面造成的差异并不明显。因此,云物理方案中考虑合理的粒子谱分布、形态和密度变化,有利于提高暴雨的模拟效果。  相似文献   

18.
ABSTRACT Numerical simulations with the Advanced Regional Prediction System （ARPS） model were performed to investigate the impact of microphysical drop size distribution （DSD） on tornadogenesis in a subtropical supercell thunderstorm over Anhui Province, eastern China. Sensitivity experiments with different intercept parameters of rain, hail and snow DSDs in a Lin-type microphysics scheme were conducted. Results showed that rain and hail DSDs have a significant impact on the simulated storm both microphysically and dynamically. DSDs characterized by larger （smaller） intercepts have a smaller （larger） particle size and a lower （higher） mass-weighted mean fall velocity, and produce relatively stronger （weaker） and wider （narrower） cold pools through enhanced （reduced） rain evaporation and hail melting processes, which are then less favorable （favorable） for tornadogenesis. However, tornadogenesis will also be suppressed by the weakened mid-level mesocyclone when the cold pool is too weak. When compared to a U.S. Great Plain case, the two microphysical processes are more sensitive to DSD variations in the present case with a higher melting level and deeper warm layer. This suggests that DSD-related cloud microphysics has a stronger influence on tornadogenesis in supercells over the subtropics than the U.S. Great Plains.  相似文献   

19.
The scientific foundation of artificial weather modification is meso- and small-scale dynamics and cloud–precipitation microphysics. Artificial weather modification requires the realistic coupling of weather patterns, dynamical processes, and microphysical processes. Now that numerical models with weather dynamical characteristics have been widely applied to artificial weather modification, several key points that should not be neglected when developing numerical models for artificial weather modification are proposed in this paper, including the dynamical equations, model resolution, cloud–precipitation microphysical processes, numerical computation method, and initial and boundary conditions. Based on several examples, approaches are offered to deal with the problems that exist in these areas.  相似文献   

20.
显式云物理方案的研究进展   总被引：4，自引：1，他引：4  
史月琴  楼小凤 《气象科技》2006,34(5):513-520
回顾了近年来显式云物理方案的研究进展。显式云方案主要有体积水方法和详细微物理方法(分档法)。体积水方法有单参数和双参数两种谱描述方法,根据模式预报变量和物理过程的不同,可以分为暖云方案、简单冰相方案和复杂冰相方案。详细的微物理方法由于预报变量繁多、计算量巨大而一般多应用于研究工作。不同的模式,有不同的显式云方案,并不是粒子分类越复杂模拟效果就越好,需要根据研究的重点、计算资源的许可选择使用不同的物理方案。物理过程参数化需要建立在理论和实验研究的基础上,因此应加强这方面的理论和实验研究,使物理参数化具有更坚实的物理基础。  相似文献   

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