Cloud microphysical processes occur at the smallest end of scales among cloud-related processes and thus must be parameterized not only in large-scale global circulation models(GCMs)but also in various higher-resoluti...Cloud microphysical processes occur at the smallest end of scales among cloud-related processes and thus must be parameterized not only in large-scale global circulation models(GCMs)but also in various higher-resolution limited-area models such as cloud-resolving models(CRMs)and large-eddy simulation(LES)models.Instead of giving a comprehensive review of existing microphysical parameterizations that have been developed over the years,this study concentrates purposely on several topics that we believe are understudied but hold great potential for further advancing bulk microphysics parameterizations:multi-moment bulk microphysics parameterizations and the role of the spectral shape of hydrometeor size distributions;discrete vs“continuous”representation of hydrometeor types;turbulence-microphysics interactions including turbulent entrainment-mixing processes and stochastic condensation;theoretical foundations for the mathematical expressions used to describe hydrometeor size distributions and hydrometeor morphology;and approaches for developing bulk microphysics parameterizations.Also presented are the spectral bin scheme and particle-based scheme(especially,super-droplet method)for representing explicit microphysics.Their advantages and disadvantages are elucidated for constructing cloud models with detailed microphysics that are essential to developing processes understanding and bulk microphysics parameterizations.Particle-resolved direct numerical simulation(DNS)models are described as an emerging technique to investigate turbulence-microphysics interactions at the most fundamental level by tracking individual particles and resolving the smallest turbulent eddies in turbulent clouds.Outstanding challenges and future research directions are explored as well.展开更多
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 LA...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.展开更多
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 ver...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.展开更多
A three-dimensional charge^lischarge numerical model is used, in a semi-idealized mode, to simulate a thunder- storm cell. Characteristics of the granpel microphysics and vertical air motion associated with the lightn...A three-dimensional charge^lischarge numerical model is used, in a semi-idealized mode, to simulate a thunder- storm cell. Characteristics of the granpel microphysics and vertical air motion associated with the lightning initiation are revealed, which could be useful in retrieving charge strength during lightning when no charge^diseharge model is available, The results show that the vertical air motion at the lightning initiation sites （Wini） has a cubic polynomial correlation with the maximum updraft of the storm cell （WceH_m^x）, with the adjusted regression coefficient R2 of ap- proximately 0.97. Meanwhile, the graupel mixing ratio at the lightning initiation sites （qg-ini） has a linear correlation with the maximum graupel mixing ratio of the storm cell （qg-cell-max） and the initiation height （Zini）, with the coeffi- cients being 0.86 and 0.85, respectively. These linear correlations are more significant during the middle and late stages of lightning activity. A zero-charge zone, namely, the area with very low net charge density between the main positive and negative charge layers, appears above the area of qg-oewm and below the upper edge of the granpel re- gion, and is found to be an important area for lightning initiation. Inside the zero-charge zone, large electric intensity forms, and the ratio of qice （ice crystal mixing ratio） to qg （graupel mixing ratio） illustrates an exponential relation- ship to qg-ini. These relationships provide valuable clues to more accurately locating the high-risk area of lightning initiation in thunderstorms when only dual-polarization radar data or outputs from numerical models without char- ging/discharging schemes are available. The results can also help understand the environmental conditions at light- ning initiation sites.展开更多
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 parame...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%.展开更多
A heavy rainfall in the Meiyu front during 4-5 July 2003 is simulated by use of the non-hydrostatic mesoscale model MM5 （V3-6） with different explicit cloud microphysical parameterization schemes. The characteristic...A heavy rainfall in the Meiyu front during 4-5 July 2003 is simulated by use of the non-hydrostatic mesoscale model MM5 （V3-6） with different explicit cloud microphysical parameterization schemes. The characteristics of microphysical process of convective cloud are studied by the model outputs. The simulation study reveals that： （1） The mesoscale model MM5 with explicit cloud microphysical process is capable of simulating the instant heavy rainfall in the Meiyu front, the rainfall simulation could be improved signifi- cantly as the model resolution is increased, and the Goddard scheme is better than the Reisner or Schultz scheme. （2） The convective cloud in the Meiyu front has a comprehensive structure composed of solid, liquid and vapor phases of water, the mass density of water vapor is the largest one in the cloud; the next one is graupel, while those of ice, snow, rain water and the cloud water are almost same. The height at which mass density peaks for different hydrometeors is almost unchangeable during the heavy rainfall period. The mass density variation of rain water, ice, and graupel are consistent with that of ground precipitation, while that of water vapor in the low levels is 1-2 h earlier than the precipitation. （3） The main contribution to the water vapor budget in the atmosphere is the convergence of vapor flux through advection and convection, which provides the main vapor source of the rainfall. Besides the basic process of the auto-conversion of cloud water to rain water, there is an additional cloud microphysical process that is essential to the formation of instant heavy rainfall, the ice-phase crystals are transformed into graupels first and then the increased graupels mix with cloud water and accelerates the conversion of cloud water to rain water. The positive feedback mechanism between latent heat release and convection is the main cause to maintain and develop the heavy precipitation.展开更多
High-resolution data of a torrential rainfall event in Sichuan, China, simulated by the WRF model, were used to analyze the cloud microphysical differences with precipitation intensity. Sixhourly accumulated rainfall ...High-resolution data of a torrential rainfall event in Sichuan, China, simulated by the WRF model, were used to analyze the cloud microphysical differences with precipitation intensity. Sixhourly accumulated rainfall was classified into five bins based on rainfall intensity, and the cloud microphysical characteristics and processes in different bins were studied. The results show that：（1） Hydrometeor content differed distinctly among different bins. Mixing ratios of cloud water, rain water, and graupel enhanced significantly and monotonously with increasing rainfall intensity. With increasing precipitation intensity, the monotonous increase in cloud water number concentration was significant. Meanwhile, number concentrations of rain water and graupel increased at first and then decreased or increased slowly in larger rainfall bins.（2） With precipitation intensity increasing, cloud microphysical conversion processes closely related to the production of rainwater, directly（accretion of cloud water by rain（QCLcr） and melting of graupel（QMLgr）） or indirectly（water vapor condensation and accretion of cloud water by graupel）, increased significantly.（3） As the two main sources of rainwater, QCLcrincreased monotonously with increasing precipitation intensity, while QMLgr increased slowly, even tending to cease increasing in larger rainfall bins.展开更多
The understanding of the cloud processes of snowfall is essential to the artificial enhancement of snow and the numerical simulation of snowfall. The mesoscale model MM5 is used to simulate a moderate snowfall event i...The understanding of the cloud processes of snowfall is essential to the artificial enhancement of snow and the numerical simulation of snowfall. The mesoscale model MM5 is used to simulate a moderate snowfall event in North China that occurred during 20-21 December 2002. Thirteen experiments are performed to test the sensitivity of the simulation to the cloud physics with different cumulus parameterization schemes and different options for the Goddard cloud microphysics parameterization schemes. It is shown that the cumulus parameterization scheme has little to do with the simulation result. The results also show that there are only four classes of water substances, namely the cloud water, cloud ice, snow, and vapor, in the simulation of the moderate snowfall event. The analysis of the cloud microphysics budgets in the explicit experiment shows that the condensation of supersaturated vapor, the depositional growth of cloud ice, the initiation of cloud ice, the accretion of cloud ice by snow, the accretion of cloud water by snow, the deposition growth of snow, and the Bergeron process of cloud ice are the dominant cloud microphysical processes in the simulation. The accretion of cloud water by snow and the deposition growth of the snow are equally important in the development of the snow.展开更多
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 Lium...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.展开更多
Based on Droplet Measurement Technologies data of a pre-stratiform-cloud precipitation event in Ganzhou, Jiangxi Province, on 11 November 2015, and combined with radar data, this paper comprehensively analyzes the mac...Based on Droplet Measurement Technologies data of a pre-stratiform-cloud precipitation event in Ganzhou, Jiangxi Province, on 11 November 2015, and combined with radar data, this paper comprehensively analyzes the macro-and microphysical characteristics of cloud in the upper trough.The results show that：（1） Detection takes place in the early stage of precipitation and the cloud has multiple layers. The cloud type is stratiform（Sc） and the height of the cloud base is 1009 m, 1009–1700 m is the low Sc layer, 1700–3000 m is the no-cloud level, and 3000 to the maximum height detected is another Sc layer.（2） The Sc is inhomogeneous in the horizontal and vertical directions.The particle number concentration and the effective diameter below the 0 °C layer is significantly higher than that above the 0 °C layer, which is in accordance with the ‘seeder–feeder＇ mechanism.Above the 0 °C layer is seeder cloud, where needle, column ice crystals and water droplets coexist,and sublimation and coalescence are the main processes. The morphology of ice crystals changes from needle to column, plate, and polymer as height decreases. Below the 0 °C warm layer is a supply cloud, and the particles develop in the supply cloud with abundant liquid water content. Ice melting and coalescence dominate the warm layer, which makes the effective diameter significantly increase. Down to 4150 m, the ice melts completely into raindrops.展开更多
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...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 that comprised （a） a control experiment （CTL）, （b） NEVPRW from which evaporation of rain water was suppressed, （c） NGP from which graupel was taken, and （d） NMLT from which melting of snow and graupel was removed. We studied the impacts of different cloud microphysical processes on the track, intensity and precipitation of the typhoon, as well as the kinematics, thermodynamics and vertical structural characteristics of hydrometeors in the inner core of the typhoon. Additionally, the budgets of the cloud microphysical processes in the fine domain were calculated to quantify the importance of each microphysical process for every sensitivity experiment. The primary results are as follows： （1） It is found that varying cloud microphysics parameters produce little sensitivity in typhoon track experiments. （2） The experiment of NGP produces the weakest storm, while the experiment of NMLT produces the strongest storm, and the experiment of NEVPRW also produces stronger storms than CTL. （3） Varying parameters of cloud rnicrophysics have obvious impacts on the precipitation, kinematics, and thermodynamics of the typhoon and the vertical structural characteristics of hydrometeors in the typhoon＇s inner core. （4） Most budgets of cloud microphysics in NMLT are larger than in CTL, while they are 20%-60% smaller in NEVPRW than in CTL.展开更多
Aerosol-cloud-radiation interactions represent one of the largest uncertainties in the current climate assessment. Much of the complexity arises from the non-monotonic responses of clouds, precipitation and radiative ...Aerosol-cloud-radiation interactions represent one of the largest uncertainties in the current climate assessment. Much of the complexity arises from the non-monotonic responses of clouds, precipitation and radiative fluxes to aerosol perturbations under various meteorological conditions. In this study, an aerosol-aware WRF model is used to investigate the microphysical and radiative effects of aerosols in three weather systems during the March 2000 Cloud Intensive Observational Period campaign at the US Southern Great Plains. Three simulated cloud ensembles include a low-pressure deep convective cloud system, a collection of less-precipitating stratus and shallow cumulus, and a cold frontal passage. The WRF simulations are evaluated by several ground-based measurements. The microphysical properties of cloud hydrometeors, such as their mass and number concentrations, generally show monotonic trends as a function of cloud condensation nuclei concentrations. Aerosol radiative effects do not influence the trends of cloud microphysics, except for the stratus and shallow cumulus cases where aerosol semi-direct effects are identified. The precipitation changes by aerosols vary with the cloud types and their evolving stages, with a prominent aerosol invigoration effect and associated enhanced precipitation from the convective sources. The simulated aerosol direct effect suppresses precipitation in all three cases but does not overturn the aerosol indirect effect. Cloud fraction exhibits much smaller sensitivity （typically less than 2%） to aerosol perturbations, and the responses vary with aerosol concentrations and cloud regimes. The surface shortwave radiation shows a monotonic decrease by increasing aerosols, while the magnitude of the decrease depends on the cloud type.展开更多
By using the microphysical data of stratiform cloud in Henan which were observed by PMS airborne cloud particle measure system on March 23 in 2007 and combining with the radar,satellite,sounding data,the macro and mic...By using the microphysical data of stratiform cloud in Henan which were observed by PMS airborne cloud particle measure system on March 23 in 2007 and combining with the radar,satellite,sounding data,the macro and micro physical structure characteristics of cloud were analyzed.The results showed that the average diameter of small cloud drop which was measured by FSSP-100 in the warm layer of cloud was mainly during 5-12 μm,and the average value was 7.33 μm.The biggest diameter of small cloud drop changed during 14-47 μm,and the average value was 27.80 μm.The total number concentration scope of small cloud drop was during 47.73-352.00 drop/cm3,and the average value was 160 drop/cm3.In the cold layer of cloud,the biggest diameter of small cloud particle(included the cloud droplet and the ice crystals)which was measured by FSSP-100 was 24.8 μm.The total number concentration scope of small cloud particle was during 0.899-641.000 drop/cm3,and the average value was 297 drop/cm3.The airborne King heat line liquid water content instrument observed that the super-cooling liquid water existed in the cloud.The super-cooling cloud water content changed during 0.02-0.20 g/m3,and the average value was 0.093 g/m3.The biggest value which was 0.202 g/m3 appeared in 4 368 m height(the temperature was-8.5 ℃).The particle spectrum type in the cloud was mainly the negative exponent type and the single peak type.展开更多
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 mic...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.展开更多
High-resolution numerical simulation data of a rainstorm triggering debris flow in Sichuan Province of China simulated by the Weather Research and Forecasting （WRF） Model were used to study the dominant cloud microp...High-resolution numerical simulation data of a rainstorm triggering debris flow in Sichuan Province of China simulated by the Weather Research and Forecasting （WRF） Model were used to study the dominant cloud microphysical processes of the torrential rainfall.The results showed that：（1） In the strong precipitation period,particle sizes of all hydrometeors increased,and mean-mass diameters of graupel increased the most significantly,as compared with those in the weak precipitation period; （2） The terminal velocity of raindrops was the strongest among all hydrometeors,followed by graupel＇s,which was much smaller than that of raindrops.Differences between various hydrometeors＇ terminal velocities in the strong precipitation period were larger than those in the weak precipitation period,which favored relative motion,collection interaction and transformation between the particles.Absolute terminal velocity values of raindrops and graupel were significantly greater than those of air upward velocity,and the stronger the precipitation was,the greater the differences between them were; （3） The orders of magnitudes of the various hydrometeors＇ sources and sinks in the strong precipitation period were larger than those in the weak precipitation period,causing a difference in the intensity of precipitation.Water vapor,cloud water,raindrops,graupel and their exchange processes played a major role in the production of the torrential rainfall,and there were two main processes via which raindrops were generated：abundant water vapor condensed into cloud water and,on the one hand,accretion of cloud water by rain water formed rain water,while on the other hand,accretion of cloud water by graupel formed graupel,and then the melting of graupel formed rain water.展开更多
This study investigates the cloud macro-and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in ...This study investigates the cloud macro-and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in Shandong province on 21 May 2018,based on the observations from the aircraft,the Suomi National Polar-Orbiting Partnership(NPP)satellite,and the high-resolution Himawari-8(H8)satellite.The aircraft observations show that convection was deeper and radar echoes were significantly enhanced with higher tops in response to seeding in the convective region.This is linked with the conversion of supercooled liquid droplets to ice crystals with released latent heat,resulting in strengthened updrafts,enhanced radar echoes,higher cloud tops,and more and larger precipitation particles.In contrast,in the stratiform cloud region,after the Silver Iodide(AgI)seeding,the radar echoes become significantly weaker at heights close to the seeding layer,with the echo tops lowered by 1.4–1.7 km.In addition,a hollow structure appears at the height of 6.2–7.8 km with a depth of about 1.6 km and a diameter of about 5.5 km,and features such as icing seeding tracks appear.These suggest that the transformation between droplets and ice particles was accelerated by the seeding in the stratiform part.The NPP and H8 satellites also show that convective activity was stronger in the convective region after seeding;while in the stratiform region,a cloud seeding track with a width of 1–3 km appears 10 km downstream of the seeding layer 15 minutes after the AgI seeding,which moves along the wind direction as width increases.展开更多
In this study, the micro-and macro-physical properties, thermal structure and precipitation characteristics of cyclone eye walls and their surrounding spiral clouds were analysed with Cloud Sat and TRMM data for five ...In this study, the micro-and macro-physical properties, thermal structure and precipitation characteristics of cyclone eye walls and their surrounding spiral clouds were analysed with Cloud Sat and TRMM data for five tropical cyclones(TCs) in 2013. The results show that the ice-phase clouds of a mature TC are mainly above 5 km. With increasing altitude, the cloud droplet effective radius decreases, and the particle number concentration increases. Ice water content first increases and then decreases with increasing height. In the eye area, in addition to the well-known warm-core area, another warm core is also apparent around the eye at a height of 8 to 15 km. The horizontal distribution of precipitation is characterized by large-scale stratiform precipitation mixed with independent convective precipitation. The height of precipitation is mostly below 7.5 km, and the heavy rain is mainly below 5 km. When the peripheral convective clouds are strong enough, ice particles would be generated, thus providing conditions that are favourable for the formation of precipitation below.展开更多
To investigate the potential effects of aerosols on the microphysical properties of warm clouds, airborne observational data collected from 2009 to 2011 in Tongliao, Inner Mongolia, China, were statistically analyzed ...To investigate the potential effects of aerosols on the microphysical properties of warm clouds, airborne observational data collected from 2009 to 2011 in Tongliao, Inner Mongolia, China, were statistically analyzed in this study. The results demonstrated that the vertical distribution of the aerosol number concentration（N_a） was similar to that of the clean rural continent. The average aerosol effective diameter（D_e） was maintained at approximately 0.4 μm at all levels. The data obtained during cloud penetrations showed that there was a progressive increase in the cloud droplet concentration（N_c） and liquid water content（LWC） from outside to inside the clouds, while the Nawas negatively related to the Ncand LWC at the same height. The fluctuation of the N_a, Ncand LWC during cloud penetration was more obvious under polluted conditions（Type 1） than under clean conditions（Type 2）. Moreover, the wet scavenging of cloud droplets had a significant impact on the accumulation mode of aerosols, especially on particles with diameters less than 0.4 μm. The minimum wet scavenging coefficient within the cloud was close to 0.02 under Type 1 conditions, while it increased to 0.1 under Type 2 conditions,which proved that the cloud wet scavenging effect under Type 1 conditions was stronger than that under Type 2 conditions.Additionally, cloud droplet spectra under Type 1 conditions were narrower, and their horizontal distributions were more homogeneous than those under Type 2 conditions.展开更多
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)schem...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.展开更多
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 becom...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.展开更多
基金supported by the US Department of Energy(DOE)’s Office of Science Atmospheric Systems Research(ASR)Programthe Office of Energy Efficiency and Renewable Energy(EERE)Solar Energy Technologies Office(SETO)award(33504)+3 种基金the Brookhaven National Laboratory(BNL)’s Laboratory Directed Research&Development Program(LDRD)(22-065)The Brookhaven National Laboratory is operated by the Brookhaven Science Associates,LLC(BSA),for the US Department of Energy under Contract No.DESC0012704supported by JSPS KAKENHI Grant No.26286089MEXT KAKENHI Grant No.18H04448。
文摘Cloud microphysical processes occur at the smallest end of scales among cloud-related processes and thus must be parameterized not only in large-scale global circulation models(GCMs)but also in various higher-resolution limited-area models such as cloud-resolving models(CRMs)and large-eddy simulation(LES)models.Instead of giving a comprehensive review of existing microphysical parameterizations that have been developed over the years,this study concentrates purposely on several topics that we believe are understudied but hold great potential for further advancing bulk microphysics parameterizations:multi-moment bulk microphysics parameterizations and the role of the spectral shape of hydrometeor size distributions;discrete vs“continuous”representation of hydrometeor types;turbulence-microphysics interactions including turbulent entrainment-mixing processes and stochastic condensation;theoretical foundations for the mathematical expressions used to describe hydrometeor size distributions and hydrometeor morphology;and approaches for developing bulk microphysics parameterizations.Also presented are the spectral bin scheme and particle-based scheme(especially,super-droplet method)for representing explicit microphysics.Their advantages and disadvantages are elucidated for constructing cloud models with detailed microphysics that are essential to developing processes understanding and bulk microphysics parameterizations.Particle-resolved direct numerical simulation(DNS)models are described as an emerging technique to investigate turbulence-microphysics interactions at the most fundamental level by tracking individual particles and resolving the smallest turbulent eddies in turbulent clouds.Outstanding challenges and future research directions are explored as well.
基金supported by the National Natural Science Funds of China(Grant No.41205071)the Ministry of Science and Technology of China for the National Basic Research Program of China(973 Program:Grant No.2011CB309704)the funding support from the U.S.Department of Energy(DOE),Office of Science,Earth System Modeling Program
文摘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.
基金National Natural Science Foundation of China(41575108,41475082,42075012)。
文摘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.
基金Supported by the National Natural Science Foundation of China(41675001 and 41405004)National(Key)Basic Research and Development(973)Program of China(2014CB441406)Basic Research Funds of Chinese Academy of Meteorological Sciences(2016Z002 and 2017Z003)
文摘A three-dimensional charge^lischarge numerical model is used, in a semi-idealized mode, to simulate a thunder- storm cell. Characteristics of the granpel microphysics and vertical air motion associated with the lightning initiation are revealed, which could be useful in retrieving charge strength during lightning when no charge^diseharge model is available, The results show that the vertical air motion at the lightning initiation sites （Wini） has a cubic polynomial correlation with the maximum updraft of the storm cell （WceH_m^x）, with the adjusted regression coefficient R2 of ap- proximately 0.97. Meanwhile, the graupel mixing ratio at the lightning initiation sites （qg-ini） has a linear correlation with the maximum graupel mixing ratio of the storm cell （qg-cell-max） and the initiation height （Zini）, with the coeffi- cients being 0.86 and 0.85, respectively. These linear correlations are more significant during the middle and late stages of lightning activity. A zero-charge zone, namely, the area with very low net charge density between the main positive and negative charge layers, appears above the area of qg-oewm and below the upper edge of the granpel re- gion, and is found to be an important area for lightning initiation. Inside the zero-charge zone, large electric intensity forms, and the ratio of qice （ice crystal mixing ratio） to qg （graupel mixing ratio） illustrates an exponential relation- ship to qg-ini. These relationships provide valuable clues to more accurately locating the high-risk area of lightning initiation in thunderstorms when only dual-polarization radar data or outputs from numerical models without char- ging/discharging schemes are available. The results can also help understand the environmental conditions at light- ning initiation sites.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41275147 and 41875173)the STS Program of Inner Mongolia Meteorological Service, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences and Institute of Atmospheric Physics, Chinese Academy of Sciences (Grant No. 2021CG0047)
文摘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%.
基金Supported by the National Basic Research Program of China under Grant No.2006CB400505the National Natural Science Foundation of China under Grant No.40675040.
文摘A heavy rainfall in the Meiyu front during 4-5 July 2003 is simulated by use of the non-hydrostatic mesoscale model MM5 （V3-6） with different explicit cloud microphysical parameterization schemes. The characteristics of microphysical process of convective cloud are studied by the model outputs. The simulation study reveals that： （1） The mesoscale model MM5 with explicit cloud microphysical process is capable of simulating the instant heavy rainfall in the Meiyu front, the rainfall simulation could be improved signifi- cantly as the model resolution is increased, and the Goddard scheme is better than the Reisner or Schultz scheme. （2） The convective cloud in the Meiyu front has a comprehensive structure composed of solid, liquid and vapor phases of water, the mass density of water vapor is the largest one in the cloud; the next one is graupel, while those of ice, snow, rain water and the cloud water are almost same. The height at which mass density peaks for different hydrometeors is almost unchangeable during the heavy rainfall period. The mass density variation of rain water, ice, and graupel are consistent with that of ground precipitation, while that of water vapor in the low levels is 1-2 h earlier than the precipitation. （3） The main contribution to the water vapor budget in the atmosphere is the convergence of vapor flux through advection and convection, which provides the main vapor source of the rainfall. Besides the basic process of the auto-conversion of cloud water to rain water, there is an additional cloud microphysical process that is essential to the formation of instant heavy rainfall, the ice-phase crystals are transformed into graupels first and then the increased graupels mix with cloud water and accelerates the conversion of cloud water to rain water. The positive feedback mechanism between latent heat release and convection is the main cause to maintain and develop the heavy precipitation.
基金supported by the Key Research Program of the Chinese Academy of Sciences[grant number KZZD-e W-05-01]the National Basic Research Program of China[973 Program,grant number 2014CB441402]
文摘High-resolution data of a torrential rainfall event in Sichuan, China, simulated by the WRF model, were used to analyze the cloud microphysical differences with precipitation intensity. Sixhourly accumulated rainfall was classified into five bins based on rainfall intensity, and the cloud microphysical characteristics and processes in different bins were studied. The results show that：（1） Hydrometeor content differed distinctly among different bins. Mixing ratios of cloud water, rain water, and graupel enhanced significantly and monotonously with increasing rainfall intensity. With increasing precipitation intensity, the monotonous increase in cloud water number concentration was significant. Meanwhile, number concentrations of rain water and graupel increased at first and then decreased or increased slowly in larger rainfall bins.（2） With precipitation intensity increasing, cloud microphysical conversion processes closely related to the production of rainwater, directly（accretion of cloud water by rain（QCLcr） and melting of graupel（QMLgr）） or indirectly（water vapor condensation and accretion of cloud water by graupel）, increased significantly.（3） As the two main sources of rainwater, QCLcrincreased monotonously with increasing precipitation intensity, while QMLgr increased slowly, even tending to cease increasing in larger rainfall bins.
基金The authors benefited from discussions with Professors C.-H.Sui and Xu Huanbin.The comments of the three anonymous reviewers are acknowledged.This research was supported by the National Natural Science Foundation of China.(Grant Nos.40375036 and 40105006).
文摘The understanding of the cloud processes of snowfall is essential to the artificial enhancement of snow and the numerical simulation of snowfall. The mesoscale model MM5 is used to simulate a moderate snowfall event in North China that occurred during 20-21 December 2002. Thirteen experiments are performed to test the sensitivity of the simulation to the cloud physics with different cumulus parameterization schemes and different options for the Goddard cloud microphysics parameterization schemes. It is shown that the cumulus parameterization scheme has little to do with the simulation result. The results also show that there are only four classes of water substances, namely the cloud water, cloud ice, snow, and vapor, in the simulation of the moderate snowfall event. The analysis of the cloud microphysics budgets in the explicit experiment shows that the condensation of supersaturated vapor, the depositional growth of cloud ice, the initiation of cloud ice, the accretion of cloud ice by snow, the accretion of cloud water by snow, the deposition growth of snow, and the Bergeron process of cloud ice are the dominant cloud microphysical processes in the simulation. The accretion of cloud water by snow and the deposition growth of the snow are equally important in the development of the snow.
基金Ministry of Science and Technology of China(2017YFC1501406)National Key Research and Development Plan Program of China(2017YFA0604500)CMA Youth Founding Program(Q201706&NWPC-QNJJ-201702)
文摘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.
基金supported by the National Natural Science Foundation of China[grant number 41530427],[grant number41590871]
文摘Based on Droplet Measurement Technologies data of a pre-stratiform-cloud precipitation event in Ganzhou, Jiangxi Province, on 11 November 2015, and combined with radar data, this paper comprehensively analyzes the macro-and microphysical characteristics of cloud in the upper trough.The results show that：（1） Detection takes place in the early stage of precipitation and the cloud has multiple layers. The cloud type is stratiform（Sc） and the height of the cloud base is 1009 m, 1009–1700 m is the low Sc layer, 1700–3000 m is the no-cloud level, and 3000 to the maximum height detected is another Sc layer.（2） The Sc is inhomogeneous in the horizontal and vertical directions.The particle number concentration and the effective diameter below the 0 °C layer is significantly higher than that above the 0 °C layer, which is in accordance with the ‘seeder–feeder＇ mechanism.Above the 0 °C layer is seeder cloud, where needle, column ice crystals and water droplets coexist,and sublimation and coalescence are the main processes. The morphology of ice crystals changes from needle to column, plate, and polymer as height decreases. Below the 0 °C warm layer is a supply cloud, and the particles develop in the supply cloud with abundant liquid water content. Ice melting and coalescence dominate the warm layer, which makes the effective diameter significantly increase. Down to 4150 m, the ice melts completely into raindrops.
基金National Science Foundation of China (40775066)Shanghai Typhoon Research Foundation (2008ST07)
文摘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 that comprised （a） a control experiment （CTL）, （b） NEVPRW from which evaporation of rain water was suppressed, （c） NGP from which graupel was taken, and （d） NMLT from which melting of snow and graupel was removed. We studied the impacts of different cloud microphysical processes on the track, intensity and precipitation of the typhoon, as well as the kinematics, thermodynamics and vertical structural characteristics of hydrometeors in the inner core of the typhoon. Additionally, the budgets of the cloud microphysical processes in the fine domain were calculated to quantify the importance of each microphysical process for every sensitivity experiment. The primary results are as follows： （1） It is found that varying cloud microphysics parameters produce little sensitivity in typhoon track experiments. （2） The experiment of NGP produces the weakest storm, while the experiment of NMLT produces the strongest storm, and the experiment of NEVPRW also produces stronger storms than CTL. （3） Varying parameters of cloud rnicrophysics have obvious impacts on the precipitation, kinematics, and thermodynamics of the typhoon and the vertical structural characteristics of hydrometeors in the typhoon＇s inner core. （4） Most budgets of cloud microphysics in NMLT are larger than in CTL, while they are 20%-60% smaller in NEVPRW than in CTL.
基金support provided by NASA ROSES14-ACMAPNSF (Award No. 1700727)+1 种基金supported by the US DOE ASR programsupport of the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA
文摘Aerosol-cloud-radiation interactions represent one of the largest uncertainties in the current climate assessment. Much of the complexity arises from the non-monotonic responses of clouds, precipitation and radiative fluxes to aerosol perturbations under various meteorological conditions. In this study, an aerosol-aware WRF model is used to investigate the microphysical and radiative effects of aerosols in three weather systems during the March 2000 Cloud Intensive Observational Period campaign at the US Southern Great Plains. Three simulated cloud ensembles include a low-pressure deep convective cloud system, a collection of less-precipitating stratus and shallow cumulus, and a cold frontal passage. The WRF simulations are evaluated by several ground-based measurements. The microphysical properties of cloud hydrometeors, such as their mass and number concentrations, generally show monotonic trends as a function of cloud condensation nuclei concentrations. Aerosol radiative effects do not influence the trends of cloud microphysics, except for the stratus and shallow cumulus cases where aerosol semi-direct effects are identified. The precipitation changes by aerosols vary with the cloud types and their evolving stages, with a prominent aerosol invigoration effect and associated enhanced precipitation from the convective sources. The simulated aerosol direct effect suppresses precipitation in all three cases but does not overturn the aerosol indirect effect. Cloud fraction exhibits much smaller sensitivity （typically less than 2%） to aerosol perturbations, and the responses vary with aerosol concentrations and cloud regimes. The surface shortwave radiation shows a monotonic decrease by increasing aerosols, while the magnitude of the decrease depends on the cloud type.
基金Supported by Henan Meteorological Science and Technology Research Project(Z200407)
文摘By using the microphysical data of stratiform cloud in Henan which were observed by PMS airborne cloud particle measure system on March 23 in 2007 and combining with the radar,satellite,sounding data,the macro and micro physical structure characteristics of cloud were analyzed.The results showed that the average diameter of small cloud drop which was measured by FSSP-100 in the warm layer of cloud was mainly during 5-12 μm,and the average value was 7.33 μm.The biggest diameter of small cloud drop changed during 14-47 μm,and the average value was 27.80 μm.The total number concentration scope of small cloud drop was during 47.73-352.00 drop/cm3,and the average value was 160 drop/cm3.In the cold layer of cloud,the biggest diameter of small cloud particle(included the cloud droplet and the ice crystals)which was measured by FSSP-100 was 24.8 μm.The total number concentration scope of small cloud particle was during 0.899-641.000 drop/cm3,and the average value was 297 drop/cm3.The airborne King heat line liquid water content instrument observed that the super-cooling liquid water existed in the cloud.The super-cooling cloud water content changed during 0.02-0.20 g/m3,and the average value was 0.093 g/m3.The biggest value which was 0.202 g/m3 appeared in 4 368 m height(the temperature was-8.5 ℃).The particle spectrum type in the cloud was mainly the negative exponent type and the single peak type.
基金supported by the National Key R&D Program of China(2017YFA0603502)(Key)National Natural Science Foundation of China(91644211)S&T Development Fund of CAMS(2021KJ004).
文摘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.
基金supported by the Key Research Program of the Chinese Academy of Sciences (Grant No. KZZD-EW-05-01)the National Basic Research Program of China (973 Program) (Grant No. 2014CB441402)
文摘High-resolution numerical simulation data of a rainstorm triggering debris flow in Sichuan Province of China simulated by the Weather Research and Forecasting （WRF） Model were used to study the dominant cloud microphysical processes of the torrential rainfall.The results showed that：（1） In the strong precipitation period,particle sizes of all hydrometeors increased,and mean-mass diameters of graupel increased the most significantly,as compared with those in the weak precipitation period; （2） The terminal velocity of raindrops was the strongest among all hydrometeors,followed by graupel＇s,which was much smaller than that of raindrops.Differences between various hydrometeors＇ terminal velocities in the strong precipitation period were larger than those in the weak precipitation period,which favored relative motion,collection interaction and transformation between the particles.Absolute terminal velocity values of raindrops and graupel were significantly greater than those of air upward velocity,and the stronger the precipitation was,the greater the differences between them were; （3） The orders of magnitudes of the various hydrometeors＇ sources and sinks in the strong precipitation period were larger than those in the weak precipitation period,causing a difference in the intensity of precipitation.Water vapor,cloud water,raindrops,graupel and their exchange processes played a major role in the production of the torrential rainfall,and there were two main processes via which raindrops were generated：abundant water vapor condensed into cloud water and,on the one hand,accretion of cloud water by rain water formed rain water,while on the other hand,accretion of cloud water by graupel formed graupel,and then the melting of graupel formed rain water.
基金supported by the National Key Research and Development Project(Grant No.2019YFA0606803,2016YFA0601704)the National Natural Science Foundation of China(Grant No.41925022)+1 种基金the Innovation and Development Project of China Meteorological Administration(CXFZ2022J036)the Science and Technology Development Fund of Hubei Meteorological Bureau(Grant No.2017Y06,2017Y07,2016Y06,2019Y10).
文摘This study investigates the cloud macro-and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in Shandong province on 21 May 2018,based on the observations from the aircraft,the Suomi National Polar-Orbiting Partnership(NPP)satellite,and the high-resolution Himawari-8(H8)satellite.The aircraft observations show that convection was deeper and radar echoes were significantly enhanced with higher tops in response to seeding in the convective region.This is linked with the conversion of supercooled liquid droplets to ice crystals with released latent heat,resulting in strengthened updrafts,enhanced radar echoes,higher cloud tops,and more and larger precipitation particles.In contrast,in the stratiform cloud region,after the Silver Iodide(AgI)seeding,the radar echoes become significantly weaker at heights close to the seeding layer,with the echo tops lowered by 1.4–1.7 km.In addition,a hollow structure appears at the height of 6.2–7.8 km with a depth of about 1.6 km and a diameter of about 5.5 km,and features such as icing seeding tracks appear.These suggest that the transformation between droplets and ice particles was accelerated by the seeding in the stratiform part.The NPP and H8 satellites also show that convective activity was stronger in the convective region after seeding;while in the stratiform region,a cloud seeding track with a width of 1–3 km appears 10 km downstream of the seeding layer 15 minutes after the AgI seeding,which moves along the wind direction as width increases.
基金Young Scientists Fund of National Natural Science Foundation of China Grant(41505013,41575017)Natural Science Foundation of Shandong Province(BS2015HZ019)
文摘In this study, the micro-and macro-physical properties, thermal structure and precipitation characteristics of cyclone eye walls and their surrounding spiral clouds were analysed with Cloud Sat and TRMM data for five tropical cyclones(TCs) in 2013. The results show that the ice-phase clouds of a mature TC are mainly above 5 km. With increasing altitude, the cloud droplet effective radius decreases, and the particle number concentration increases. Ice water content first increases and then decreases with increasing height. In the eye area, in addition to the well-known warm-core area, another warm core is also apparent around the eye at a height of 8 to 15 km. The horizontal distribution of precipitation is characterized by large-scale stratiform precipitation mixed with independent convective precipitation. The height of precipitation is mostly below 7.5 km, and the heavy rain is mainly below 5 km. When the peripheral convective clouds are strong enough, ice particles would be generated, thus providing conditions that are favourable for the formation of precipitation below.
基金jointly supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA05100304)the Chinese Natural Science Foundation (Grant No. 41005073)
文摘To investigate the potential effects of aerosols on the microphysical properties of warm clouds, airborne observational data collected from 2009 to 2011 in Tongliao, Inner Mongolia, China, were statistically analyzed in this study. The results demonstrated that the vertical distribution of the aerosol number concentration（N_a） was similar to that of the clean rural continent. The average aerosol effective diameter（D_e） was maintained at approximately 0.4 μm at all levels. The data obtained during cloud penetrations showed that there was a progressive increase in the cloud droplet concentration（N_c） and liquid water content（LWC） from outside to inside the clouds, while the Nawas negatively related to the Ncand LWC at the same height. The fluctuation of the N_a, Ncand LWC during cloud penetration was more obvious under polluted conditions（Type 1） than under clean conditions（Type 2）. Moreover, the wet scavenging of cloud droplets had a significant impact on the accumulation mode of aerosols, especially on particles with diameters less than 0.4 μm. The minimum wet scavenging coefficient within the cloud was close to 0.02 under Type 1 conditions, while it increased to 0.1 under Type 2 conditions,which proved that the cloud wet scavenging effect under Type 1 conditions was stronger than that under Type 2 conditions.Additionally, cloud droplet spectra under Type 1 conditions were narrower, and their horizontal distributions were more homogeneous than those under Type 2 conditions.
基金the National Natural Science Foundation of China(Grant No.42075083)National Key Research and Development Program of China(Grant No.2019YFC1510400)+1 种基金Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030004)the Second Tibetan Plateau Scientific Expe-dition and Research(STEP)program(2019QZKK010402)。
文摘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.
基金Acknowledgments. Thanks to Dr. Alexander MacDonald of NOAA/FSL for his support throughout this study, and to Professors William Cotton. Roger Pielke. Wayne Schubert of Colorado State University, and to Dr. Fanyou Kong of University of Oklahoma and Mr. Hu
文摘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.
