A STUDY OF THE INFLUENCE OF MICROPHYSICAL PROCESSES ON TYPHOON NIDA(2016) USING A NEW DOUBLE-MOMENT MICROPHYSICS SCHEME IN THE WEATHER RESEARCH AND FORECASTING MODEL

The basic structure and cloud features of Typhoon Nida(2016) are simulated using a new microphysics scheme(Liuma) within the Weather Research and Forecasting(WRF) model. Typhoon characteristics simulated with the Liuma microphysics scheme are compared with observations and those simulated with a commonly-used microphysics scheme(WSM6). Results show that using different microphysics schemes does not significantly alter the track of the typhoon but does significantly affect the intensity and the cloud structure of the typhoon. Results also show that the vertical distribution of cloud hydrometeors and the horizontal distribution of peripheral rainband are affected by the microphysics scheme. The mixing ratios of rain water and graupel correlate highly with the vertical velocity component and equivalent potential temperature at the typhoon eye-wall region. According to the simulation with WSM 6 scheme,it is likely that the very low typhoon central pressure results from the positive feedback between hydrometeors and typhoon intensity. As the ice-phase hydrometeors are mostly graupel in the Liuma microphysics scheme, further improvement in this aspect is required.

A Modified Double-Moment Bulk Microphysics Scheme Geared toward the East Asian Monsoon Region

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.

NUMERICAL SIMULATION OF CLOUD MICROPHYSICAL CHARACTERISTICS OF LANDFALL TYPHOON KROSA

In this study,the super typhoon KROSA(2007)was simulated using a mesoscale numerical model Global and Regional Assimilation and Prediction System(GRAPES)with a two-moment mixed-phase microphysics scheme.Local rainfall observations,radar and satellite data were also used to analyze the precipitation structure and microphysical features.It was shown that low-level jets and unstable temperature stratification provided this precipitation process with favorable weather condition.Heavy rainfall centers were located in the north and east part of KROSA with the maxima of 6-hourly total rainfall during the simulation more than 100 mm.The quantities of column solid water and column liquid water were generally equivalent,indicating the important role of ice phase in precipitation formation.Results of CloudSat showed that strong convection occurred in the eyewall around the cyclonic center.According to the simulation results,heavy precipitation in the northeast part of the typhoon was mainly triggered by convective clouds,accompanied by the strongest updraft under the melting level.In the southwest part of KROSA,precipitation intensity was rather homogeneous.The ascending center occurred in high-level cold clouds,favoring the formation and growth of ice particles.

The Importance of the Shape Parameter in a Bulk Parameterization Scheme to the Evolution of the Cloud Droplet Spectrum during Condensation

The shape parameter of the Gamma size distribution plays a key role in the evolution of the cloud droplet spectrum in the bulk parameterization schemes. However, due to the inaccurate specification of the shape parameter in the commonly used bulk double-moment schemes, the cloud droplet spectra cannot reasonably be described during the condensation process. Therefore, a newly-developed triple-parameter condensation scheme with the shape parameter diagnosed through the number concentration, cloud water content, and reflectivity factor of cloud droplets can be applied to improve the evolution of the cloud droplet spectrum. The simulation with the new parameterization scheme was compared to those with a high-resolution Lagrangian bin scheme, the double-moment schemes in a parcel model, and the observation in a 1.5D Eulerian model that consists of two cylinders. The new scheme with the shape parameter varying with time and space can accurately simulate the evolution of the cloud droplet spectrum. Furthermore, the volume-mean radius and cloud water content simulated with the new scheme match the Lagrangian analytical solutions well, and the errors are steady, within approximately 0.2%.

Variational Assimilation of Satellite Cloud Water/Ice Path and Microphysics Scheme Sensitivity to the Assimilation of a Rainfall Case

Hydrometeor variables （cloud water and cloud ice mixing ratios） are added into the WRF three-dimensional variational assimilation system as additional control variables to directly analyze hydrometeors by assimilating cloud observations. In addition, the background error covariance matrix of hydrometeors is modeled through a control variable transform, and its characteristics discussed in detail. A suite of experiments using four microphysics schemes （LIN, SBU-YLIN, WDM6 and WSM6） are performed with and without assimilating satellite cloud liquid/ice water path. We find analysis of hydrometeors with cloud assimilation to be significantly improved, and the increment and distribution of hydrometeors are consistent with the characteristics of background error covariance. Diagnostic results suggest that the forecast with cloud assimilation represents a significant improvement, especially the ability to forecast precipitation in the first seven hours. It is also found that the largest improvement occurs in the experiment using the WDM6 scheme, since the assimilated cloud information can sustain for longer in this scheme. The least improvement, meanwhile, appears in the experiment using the SBU-YLIN scheme.

Impact of Different Cloud Microphysics Parameterization Schemes on Typhoon Intensity and Structure

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 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 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.

LASG Global AGCM with a Two-moment Cloud Microphysics Scheme:Energy Balance and Cloud Radiative Forcing Characteristics

Cloud dominates influence factors of atmospheric radiation, while aerosol–cloud interactions are of vital importance in its spatiotemporal distribution. In this study, a two-moment(mass and number) cloud microphysics scheme, which significantly improved the treatment of the coupled processes of aerosols and clouds, was incorporated into version 1.1 of the IAP/LASG global Finite-volume Atmospheric Model(FAMIL1.1). For illustrative purposes, the characteristics of the energy balance and cloud radiative forcing(CRF) in an AMIP-type simulation with prescribed aerosols were compared with those in observational/reanalysis data. Even within the constraints of the prescribed aerosol mass, the model simulated global mean energy balance at the top of the atmosphere(TOA) and at the Earth’s surface, as well as their seasonal variation, are in good agreement with the observational data. The maximum deviation terms lie in the surface downwelling longwave radiation and surface latent heat flux, which are 3.5 W m-2(1%) and 3 W m-2(3.5%), individually. The spatial correlations of the annual TOA net radiation flux and the net CRF between simulation and observation were around 0.97 and 0.90, respectively. A major weakness is that FAMIL1.1 predicts more liquid water content and less ice water content over most oceans. Detailed comparisons are presented for a number of regions, with a focus on the Asian monsoon region(AMR). The results indicate that FAMIL1.1 well reproduces the summer–winter contrast for both the geographical distribution of the longwave CRF and shortwave CRF over the AMR. Finally, the model bias and possible solutions, as well as further works to develop FAMIL1.1 are discussed.

Evaluating the Impacts of Cloud Microphysical and Overlap Parameters on Simulated Clouds in Global Climate Models

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.

Two-moment Bulk Stratiform Cloud Microphysics in the Grid-point Atmospheric Model of IAP LASG (GAMIL)

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 rep- resentation 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. ~rthermore, 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.

Applying the WRF Double-Moment Six-Class Microphysics Scheme in the GRAPES_Meso Model： A Case Study

This study incorporated the Weather Research and Forecasting（WRF） model double-moment 6-class（WDM6） microphysics scheme into the mesoscale version of the Global/Regional Assimilation and Pr Ediction System（GRAPES_Meso）. A rainfall event that occurred during 3–5 June 2015 around Beijing was simulated by using the WDM6, the WRF single-moment 6-class scheme（WSM6）, and the NCEP 5-class scheme, respectively. The results show that both the distribution and magnitude of the rainfall simulated with WDM6 were more consistent with the observation. Compared with WDM6, WSM6 simulated larger cloud liquid water content, which provided more water vapor for graupel growth, leading to increased precipitation in the cold-rain processes. For areas with the warmrain processes, the sensitivity experiments using WDM6 showed that an increase in cloud condensation nuclei（CCN）number concentration led to enhanced CCN activation ratio and larger cloud droplet number concentration（Nc） but decreased cloud droplet effective diameter. The formation of more small-size cloud droplets resulted in a decrease in raindrop number concentration（Nr）, inhibiting the warm-rain processes, thus gradually decreasing the amount of precipitation. For areas mainly with the cold-rain processes, the overall amount of precipitation increased; however, it gradually decreased when the CCN number concentration reached a certain magnitude. Hence, the effect of CCN number concentration on precipitation exhibits significant differences in different rainfall areas of the same precipitation event.

不同云微物理方案对飞机结冰气象条件预测评估分析

飞行安全在复杂气象条件下易受结冰影响而受到威胁。能够结合地形特征并准确预测结冰气象条件是保障飞行安全的重要因素。本文利用中尺度天气预报模型模式,以4种不同的云微物理方案组合对美国华盛顿山地区的两次结冰事件进行了数值模拟。结果表明:预测的液态水含量和温度与现有文献匹配较好,而Morrison方案组合在误差分析中表现最佳。此外,讨论了水平分辨率和云微物理方案对液态水含量和云中液滴平均有效直径预测的敏感性。由于地形所引起的垂直运动是产生云水的主要动因,较高的水平分辨率能够做出更为准确的预测。最后利用IC指数对结冰强度进行了分析,表明结冰严重程度具有明显的时空多变特性,以及对云微物理方案的敏感性。本文工作有望加强对云微物理方案的理解和认识,并为选择适合的云微物理方案进行结冰天气预测提供了依据。

一次江淮暴雨高分辨率数值预报中云微物理方案敏感性分析

基于全可压非静力中尺度预报模式WRF,选取Lin、WSM3、WSM5、WSM6、Goddard五种云微物理方案和Kain-Fritsch积云对流参数化方案,对2017年6月10日的江淮暴雨过程开展高分辨率数值预报试验,重点研究了云微物理方案对强降水预报的敏感性。结果表明:Lin方案模拟的局地暴雨区降水量随时间的演变与实况较为吻合,但降雨量偏小,WSM5、WSM6和Goddard方案模拟的降水量级与实况更为吻合;不同云微物理方案对此次江淮暴雨的预报能力具有明显差异,小雨量区域的模拟效果基本一致,暴雨和大暴雨对云微物理方案更加敏感;云中水成物的三维结构特征差异明显,其水成物含量也显著不同。WSM5方案模拟的雨水和云水含量较高,其降水量和落区质量较好;不同微物理方案产生差异明显的垂直速度,导致云量、云高有所差异,进而影响降水预报的性能,说明选用更为敏感的云微物理方案对降水预报质量的改善具有重要作用。

Influences of Graupel Microphysics on CMA-GFS Simulation of Summer Regional Precipitation

The horizontal resolution of global numerical weather prediction models is continuously developing. However, due to the imperfect precipitation simulation/forecast of these models, the demand for considering riming particles in cloud microphysical schemes in these models is increasing. This study employed the latest versions of global atmospheric reanalysis data (ERA5), the satellite retrieval data of the Global Precipitation Observation Program (GPM),and station precipitation observations to explore the impacts of adding graupel to the cloud microphysical scheme in the China Meteorological Administration-Global Forecast System (CMA-GFS) on summer regional precipitation simulations in four Chinese climate zones. The results verify that the new graupel scheme can enable CMA-GFS to decently predict global graupel distribution, especially in tropical and midlatitude regions. The addition of graupel in the cloud microphysics increases the precipitation simulation in North China, while that in Southwest China is weakened and dispersed. Moreover, graupel scheme increases the precipitation simulations of almost all magnitudes.The increase in light rain is obvious, and the absolute value of heavy rain is strengthened. This may be because graupel quickly melts into rain after falling out of the zero-temperature layer due to its large mass and fast falling speed, increasing surface precipitation. In summary, the addition of graupel in the cloud microphysical scheme can improve CMA-GFS’s underestimation of strong precipitation.

冰晶核化对雷暴云微物理过程和起电影响的数值模拟研究

本文在已有的二维对流云模式中采用了一种与气溶胶有关的冰晶核化方案替代原有的冰晶核化经验公式,并选取个例,分别就两种方案进行了模拟对比试验。模拟结果表明:(1)新方案所得冰晶比含水量主要分布在-0.1^-7.6°C温区之间,高于原方案所得的-50.1^-24.2°C温区;在整个雷暴云的发展过程中新方案冰晶的分布高度、温度区间以及最大浓度值均大于原方案。(2)在新方案中,温度相对较高的过冷区产生大量冰晶,其争食云中水汽抑制了云滴、雨滴的增长。此外,与原方案相比,霰增长受雨滴大幅减小的影响进一步得到限制,导致生成的霰小于原方案,且空间分布具有较大区别。(3)两方案在雷暴云初期形成的电荷结构不同;在发展旺盛与消散阶段新方案中电荷空间分布区域和电荷量均大于原方案,此外,在不同时刻主正电荷区和主负电荷区的中心高度存在差异。本文对云微物理过程及起电的分析为后继探讨气溶胶与雷暴云起放电过程、电荷结构之间的相互关系提供了有利条件。

MM5中新显式云物理方案的建立和数值模拟

在MM5动力框架内,在其中Reisner2方案基础上采用双变参数方案,增加了云水、雨水、雪和霰的数浓度预报方程。云中凝结核CCN的数浓度采用超几何函数表示;云水向雨水的自动转换过程考虑了云滴谱的特征和发展变化对该过程的影响,而不是采用原方案给定阈值的方法描述该过程;对连续碰并方程不再将粒子落速差作为常量提出积分号外,而是直接作为粒子直径函数在积分号内求解,这样处理可以回避使用粒子群的平均落速带来的误差;增加了霰和雪、霰和冰晶的碰并微物理过程。粒子引入Г分布谱函数,对微物理过程采用了与之相适应的计算公式。通过增加新预报量的计算和输出程序,在MM5的显式方案中新增加了一个可选方案,并称之为新方案。模拟了一次层状云降水过程,在区域二分别采用了新方案和Reisner2方案以作对比。新旧方案降水模拟结果的对比表明新方案在降水范围和强度的预报效果有所改进。模拟结果给出了层状云的合理微观结构和它的一些特征,增强了MM5研究微观云物理的能力;通过单站微物理过程分析,揭示了降水过程的可能形成机制。说明新方案可以为层状云的宏微观结构特征、降水物理过程和人工影响天气研究提供一定依据。

三相云显式降水方案和高原东部“96.1”暴雪成因的中尺度数值模拟

对“96.1”高原暴雪天气过程进行的天气学成因分析指出 ,欧洲阻高崩溃 ,里海—咸海横槽转竖 ,槽后向南入侵青藏高原的干冷偏北气流与槽前来自孟加拉湾和中印半岛向北不断推进的强劲西南暖湿气流 ,在青藏高原东北部交汇而形成、发展并持续的切变线 ,是产生高原暴雪的中尺度天气系统。 通过将冰相云微物理过程参数化和三相云显式降水方案引入MM4而发展的中尺度模式模拟系统 ,在采用常规观测资料的条件下 ,基本上成功地模拟出了“96.1”高原暴雪中尺度切变线的生成、发展和演变结构。结果表明 ,发展和改进的该中尺度模式模拟系统可用于青藏高原复杂地形和下垫面上中尺度系统发生、发展及结构演变的数值模拟研究。 模拟的流场及诸物理场时空演变揭示 :流场辐合线与暴雪切变线时空演变一致表明 ,流场对高原中尺度系统的表征有本质上的重要性 ;散度场和涡度场相互耦合是暴雪切变线发生、发展的重要动力机制 ;垂直上升运动的加强和持续是水汽凝结和冻结成雪的必要条件 ;湿对流不稳定为暴雪提供了热力不稳定条件 ;辐合带、涡度带、上升运动区和深厚湿舌的迭置是产生暴雪的强耦合结构。模拟的暴雪带和降水量与观测分析大体一致 ,表明三相云显式降水方案基本上是合理的。

云凝结核浓度对WRF模式模拟飑线降水的影响:不同云微物理参数化方案的对比研究

采用WRF模式模拟一次影响中国广东省的飑线过程,分别选取Morrison、Thompson07、Thompson09和WDM6云微物理方案实施了四组试验,每组试验包括不同云凝结核(CCN)浓度的三次模拟,称为"低浓度"、"中浓度"和"高浓度",将模拟区域划分为深对流、浅对流和层云区域,对比分析四组试验中CCN浓度变化对模拟的总降水量、不同区域降水率和不同区域面积的影响,进一步分析了云微物理过程、动力环流强度等受CCN浓度变化的影响。发现:(1)由于不同云微物理过程与CCN浓度有着直接或间接的联系、不同云微物理过程之间存在复杂的关联、云微物理过程与动力环流之间发生非线性耦合,采用不同的云微物理方案导致模拟的CCN—降雨影响既有相似、也有差异;(2)模拟的CCN—降水影响在采用Thompson09和Thompson07方案时更显著,采用WDM6方案时最小;(3)四组模拟试验均出现CCN浓度增加延迟降水产生、初期降水减弱的情况,在模拟后期降水量也随着CCN浓度增加而减小,而飑线成熟阶段CCN—降水影响更加复杂。

超强台风“威马逊”(2014)云微物理特征的模拟与对比分析

采用中尺度数值模式WRFv3.5对2014年超强台风"威马逊"进行数值模拟。利用雷达、卫星、自动站逐时降水资料,对比单参数WSM6云方案和双参数WDM6云方案在模拟台风路径、强度、降水分布及水成物含量上的差异,分析雨滴粒子的谱型特征及微物理源、汇项对云中雨水含量的影响。与上海台风研究所的最佳路径数据对比显示,两方案均较好地模拟出了台风"威马逊"的移动路径,WDM6方案的整体路径误差更小;模拟的强度差异则较为显著,WDM6方案的海平面最低气压值偏高,强度偏弱。两方案模拟的累积降雨分布虽与自动站实测资料基本一致,但WDM6方案模拟的强降水概率偏高,弱降水概率偏低。两方案模拟的对流区雪、霰、雨水含量均大于TRMM卫星反演结果,且WDM6方案的对流云较多,总体雨水含量偏高;两方案均模拟出了雷达回波分布的整体特征,但眼区尺度偏大,WDM6方案在融化层以下缺少眼墙之外的弱回波区且大于39 dBz的强回波区偏多,同样显示了雨水含量(或尺度)偏大。由于WDM6方案为暖雨(云、雨水)双参数模式,对云滴活化、云雨转换及云、雨谱型有一定的改进,其能较合理地模拟出雨滴谱随台风发展的演变特征;模拟显示,云、雨滴的收集碰并及固态粒子的融化是雨水的主要源项,WDM6方案增加了云雨水自动转化率及雨水碰并云水率,导致该方案的空中雨水含量偏高,且随高度的降低快速减小;此外,由于WDM6方案使用简单的寇拉公式进行云滴活化,初始云凝结核数的变化即可造成雪、霰、云雨水含量的改变,故建议在具体大气气溶胶条件下,对方案中的云滴生成参数化过程做相应的调整。

2013年“菲特”台风暴雨数值模拟中微物理方案的对比试验

利用TRMM（热带测雨雷达）搭载的TMI（微波成像仪）反演廓线资料,分析＂菲特＂台风登陆前、后云团内部水凝物的分布种类,依此选择WRF区域中尺度模式下符合条件的6个云微物理过程参数化方案（Lin,WSM6,Godgce,WDM6,Morrison以及Thompson方案）,模拟2013年10月6～8日的台风过程.从降水落区、强度,水凝物及风场垂直分布,台风路径及强度等方面对预报性能进行对比,结果表明,选用的6个云微物理方案都较好地模拟了浙江暴雨的范围和强度.结合Ts评分,降水量级越大,模拟效果对云微物理方案选择越敏感,其中,Lin方案效果最佳,尤其对极端降水的模拟,其次为WSM6、WDM6及Thompson方案,Morrison和Godgce方案相对较差.结合水凝物平均值廓线分布发现,除WDM6方案外,其他方案对暖雨过程的模拟基本一致,而对冰相过程的模拟6个方案差别较大;同时,各方案对风分量的模拟结果较水凝物廓线差别小,说明对于动力因素模拟不敏感.另外,6个方案对于台风强度的模拟整体偏弱,相较之下,Lin方案较好地模拟了强度变化趋势.

华北层状云系人工增雨个例数值研究

利用耦合了CAMS详尽云方案和非静力中尺度数值模式MM5V3的CAMS中尺度云分辨模式对2008年3月20—21日环北京地区的一次层状云系降水进行模拟和人工催化数值试验。模拟自然降水分布与实测结果一致,分析微物理特征并在所得分析的基础上进行催化试验。研究在不同催化剂量、高度进行试验对降水的影响。结果表明:在过冷水含量高且冰晶含量低的区域引入人工冰晶可使地面降水增加。引入人工冰晶后催化区域水汽明显减少,云水也有减少,冰晶粒子和雪粒子增加,而且水汽减少的量明显大于过冷云水的减少量。同时催化后550 hPa附近的下沉气流中心变为上升气流,动力、热力效应明显。雪碰并冰晶增长、冰晶转化成雪增长是催化高度附近雪晶增加的主要过程,而催化高度以下,雪碰并过冷云滴增长是雪晶增加的主要过程;雪晶碰并过冷雨滴增长是霰粒子增加的主要过程;雨滴碰并云滴增长是雨滴增长的主要过程。