Using the Weather Research and Forecasting(WRF)model with two different microphysics schemes,the Predicted Particle Properties(P3)and the Morrison double-moment parameterizations,we simulated a stratiform rainfall eve...Using the Weather Research and Forecasting(WRF)model with two different microphysics schemes,the Predicted Particle Properties(P3)and the Morrison double-moment parameterizations,we simulated a stratiform rainfall event on 20–21 April 2010.The simulation output was compared with precipitation and aircraft observations.The aircraft-observed moderate-rimed dendrites and plates indicated that riming contributed significantly to ice particle growth at the mature precipitation stage.Observations of dendrite aggregation and capped columns suggested that aggregation coexisted with deposition or riming and played an important role in producing many large particles.The domain-averaged values of the 24-h surface precipitation accumulation from the two schemes were quite close to each other.However,differences existed in the temporal and spatial evolutions of the precipitation distribution.An analysis of the surface precipitation temporal evolution indicated faster precipitation in Morrison,while P3 indicated slower rainfall by shifting the precipitation pattern eastward toward what was observed.The differences in precipitation values between the two schemes were related to the cloud water content distribution and fall speeds of rimed particles.P3 simulated the stratiform precipitation event better as it captured the gradual transition in the mass-weighted fall speeds and densities from unrimed to rimed particles.展开更多
In this study we observed the microphysical properties, including the vertical and horizontal distributions of ice particles,liquid water content and ice habit, in different regions of a slightly supercooled stratifor...In this study we observed the microphysical properties, including the vertical and horizontal distributions of ice particles,liquid water content and ice habit, in different regions of a slightly supercooled stratiform cloud. Using aircraft instrument and radar data, the cloud top temperature was recorded as higher than -15℃, behind a cold front, on 9 September 2015 in North China. During the flight sampling, the high ice number concentration area was located in the supercooled part of a shallow convective cloud embedded in a stratiform cloud, where the ambient temperature was around -3℃. In this area,the maximum number concentrations of particles with diameter greater than 100 μm and 500 μm（N_（100） and N_（500）） exceeded 300 L-（-1） and 30 L-（-1）, respectively, and were related to large supercooled water droplets with diameter greater than 24 μm derived from cloud–aerosol spectrometer probe measurements. The ice particles types in this region were predominantly columnar, needle, graupel, and some freezing drops, suggesting that the occurrence of high ice number concentrations was likely related to the Hallett–Mossop mechanism, although many other ice multiplication processes cannot be totally ruled out.The maximum ice number concentration obtained during the first penetration was around two to three orders of magnitude larger than that predicted by the Demott and Fletcher schemes when assuming the cloud top temperature was around-15℃.During the second penetration conducted within the stratiform cloud, N_（100） and N_（500） decreased by a factor of five to ten, and the presence of columnar and needle-like crystals became very rare.展开更多
The microphysical "three-layer" model for stratiform clouds over a midlatitude location in Northwest China is investigated by combining in situ airborne Particle Measuring Systems, Inc. (PMS), radar measurem...The microphysical "three-layer" model for stratiform clouds over a midlatitude location in Northwest China is investigated by combining in situ airborne Particle Measuring Systems, Inc. (PMS), radar measurements, and the NCAR/Penn State Mesoscale Model Version 5 (MM5) simulation with a two-moment microphysics scheme. The coexistence of measured supercooled liquid water and small ice particles produces snow particles below the cloud top in the second layer. Peak number concentration and mean diameter of cloud water and raindrop appear in the third warm layer. A thin dry layer just below the melting layer is also observed. The predicted precipitation is tested by equitable threat score. The melting layer is clearly defined in the radar image and model radar reflectivity output is agreement with the observations. The model results provide features of the microphysical structure for every layer of "three-layer" model at Yan'an station. For both observation and model simulation, the "three-layer" model explains the stratiform precipitation formation completely and comprehensively.展开更多
The rainout-removal of SO2 and the acidification of precipitation from stratiform clouds are simulated using a one-dimensional, time-dependent model, parameterized microphysically in which dissolution and dissociation...The rainout-removal of SO2 and the acidification of precipitation from stratiform clouds are simulated using a one-dimensional, time-dependent model, parameterized microphysically in which dissolution and dissociation of gaseous SO2 and H2O2, and oxidation reaction in aqueous phase are taken into account. The effects of dynamic factors, including updraft flow and turbulent transport, and the concentration of gaseous SO2 and H2O2 being transported into the clouds on pH value of the precipitation, the conversion rate S(Ⅳ)-S(Ⅵ) and the wet deposition rate of SO2 are discussed.展开更多
Cloud is essential in the atmosphere, condensing water vapor and generating strong convective or large-scale persistent precipitation. In this work, the relationships between cloud vertical macro- or microphysical pro...Cloud is essential in the atmosphere, condensing water vapor and generating strong convective or large-scale persistent precipitation. In this work, the relationships between cloud vertical macro- or microphysical properties, radiative heating rate, and precipitation for convective and stratiform clouds in boreal summer over the Tibetan Plateau (TP) are analyzed and compared with its neighboring land and tropical oceans based on CloudSat/CALIPSO satellite measurements and TRMM precipitation data. The precipitation intensity caused by convective clouds is twofold stronger than that by stratiform clouds. The vertical macrophysics of both cloud types show similar features over the TP, with the region weakening the precipitation intensity and compressing the cloud vertical expansion and variation in cloud top height, but having an uplift effect on the average cloud top height. The vertical microphysics of both cloud types under conditions of no rain over the TP are characterized by lower-level ice water, ice particles with a relatively larger range of sizes, and a relatively lower occurrence of denser ice particles. The features are similar to other regions when precipitation enhances, but convective clouds gather denser and larger ice particles than stratiform clouds over the TP. The atmospheric shortwave (longwave) heating (cooling) rate strengthens with increased precipitation for both cloud types. The longwave cooling layer is thicker when the rainfall rate is less than 100 mm d?1, but the net heating layer is typically compressed for the profiles of both cloud types over the TP. This study provides insights into the associations between clouds and precipitation, and an observational basis for improving the simulation of convective and stratiform clouds over the TP in climate models.展开更多
An aircraft precipitation operation and detecting was implemented by Hebei Weather Modification Office over Shijiazhuang City during18:18-19:37 on April 2,2014. The detecting area was near 500 hP a of high-altitude tr...An aircraft precipitation operation and detecting was implemented by Hebei Weather Modification Office over Shijiazhuang City during18:18-19:37 on April 2,2014. The detecting area was near 500 hP a of high-altitude trough and surface inverted trough. Slight shower had appeared in Tianjin( rear of inverted trough) and Shanxi Province( near the inverted trough) at 20:00,while there was not precipitation in Hebei Province which was near the inverted trough. Analysis showed that the water vapor supply was not enough below 550 hP a in south-central Hebei Province,and cloud system development condition was poor. The cold cloud developed better,but there was not warm cloud,causing no precipitation on the ground.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
We introduced the two-parameter stratiform cloud model of Hu and Yan (1986) into the mesoscale model ofAnthes et al. (1987), and reprogramed the latter, then constructed a three-dimensional stratiform cloud system mod...We introduced the two-parameter stratiform cloud model of Hu and Yan (1986) into the mesoscale model ofAnthes et al. (1987), and reprogramed the latter, then constructed a three-dimensional stratiform cloud system modelwhich includes three phases of water and detailed cloud physical processes. For the stability and accuracy of calculationin a larger time step, we accepted a set of hybrid-schemes for all and the time split scheme for some of the cloud physicalprocesses, and proposed a parameterized method which calculates different types of phase change processessimultaneously, and designed the falling schemes of particles following the Lagrangian method.We used a dry model, a cumulus parameterization model, a two-phase explicit scheme model, and the model pres-ented here to simulate two low-level mesoscale vortices, compared and analysed the simulating capability of these mod-els. The results show that in simulation of the circulation structure of meso-vortex, the structure of cloud system, andsurface precipitation, the model presented here is more reasonable and closer to the observations than other models.展开更多
A 2-D slab-symmetric model of mixed convective-stratiform cloud is developed by superimposing convective cloud-size field on the convergence field,in order to simulate and study the mixed clouds consisting of stratifo...A 2-D slab-symmetric model of mixed convective-stratiform cloud is developed by superimposing convective cloud-size field on the convergence field,in order to simulate and study the mixed clouds consisting of stratiform cloud and convective cloud.A deep convective,anelastic and conservative system of equations with basic variables(V,θ,π')is solved by a new method to calculate dynamic field.The water substance in the cloud is divided into 6 categories and the microphysical processes are described in spectrum with two variable parameters and more reasonable particle number/size distributions.To compare with measured radar echo intensity and structure,the model may calculate echo intensity of the model cloud observed by radar.展开更多
This study investigates the characteristics of secondary eyewall formation(SEF)in idealized tropical cyclones embedded in vertical wind shear(VWS)at different heights.The results show that upper-layer VWS at a relativ...This study investigates the characteristics of secondary eyewall formation(SEF)in idealized tropical cyclones embedded in vertical wind shear(VWS)at different heights.The results show that upper-layer VWS at a relatively low shear height is more favorable for SEF than upper-layer VWS at a relatively high shear height and lowerlayer VWS.In the experiments with upper-layer VWS at a relatively low shear height,better-organized stratiform clouds are located in the downwind sector of outer rainbands.The low-level descending inflow associated with the stratiform sector is stronger in these experiments than in the experiments with upper-layer VWS at a relatively high shear height and lower-layer VWS.The enhanced descending inflow can trigger supergradient winds and convergence near the top of the boundary layer,close to three times the radius of the maximum wind,where convection is locally forced.The subsequent convection axisymmetrization leads to SEF.展开更多
基金supported by the National Key Research and Development Program of China (Grant No. 2018YFC1507900)the National Natural Science Foundation of China (Grant Nos. 41575131, 41530427 and 41875172)
文摘Using the Weather Research and Forecasting(WRF)model with two different microphysics schemes,the Predicted Particle Properties(P3)and the Morrison double-moment parameterizations,we simulated a stratiform rainfall event on 20–21 April 2010.The simulation output was compared with precipitation and aircraft observations.The aircraft-observed moderate-rimed dendrites and plates indicated that riming contributed significantly to ice particle growth at the mature precipitation stage.Observations of dendrite aggregation and capped columns suggested that aggregation coexisted with deposition or riming and played an important role in producing many large particles.The domain-averaged values of the 24-h surface precipitation accumulation from the two schemes were quite close to each other.However,differences existed in the temporal and spatial evolutions of the precipitation distribution.An analysis of the surface precipitation temporal evolution indicated faster precipitation in Morrison,while P3 indicated slower rainfall by shifting the precipitation pattern eastward toward what was observed.The differences in precipitation values between the two schemes were related to the cloud water content distribution and fall speeds of rimed particles.P3 simulated the stratiform precipitation event better as it captured the gradual transition in the mass-weighted fall speeds and densities from unrimed to rimed particles.
基金jointly supported by the National Natural Science Foundation of China(Grant Nos.41475028 and 41405128)the“Strategic Priority Research Program”of the Chinese Academy of Sciences(Grant No.XDA05100304)
文摘In this study we observed the microphysical properties, including the vertical and horizontal distributions of ice particles,liquid water content and ice habit, in different regions of a slightly supercooled stratiform cloud. Using aircraft instrument and radar data, the cloud top temperature was recorded as higher than -15℃, behind a cold front, on 9 September 2015 in North China. During the flight sampling, the high ice number concentration area was located in the supercooled part of a shallow convective cloud embedded in a stratiform cloud, where the ambient temperature was around -3℃. In this area,the maximum number concentrations of particles with diameter greater than 100 μm and 500 μm（N_（100） and N_（500）） exceeded 300 L-（-1） and 30 L-（-1）, respectively, and were related to large supercooled water droplets with diameter greater than 24 μm derived from cloud–aerosol spectrometer probe measurements. The ice particles types in this region were predominantly columnar, needle, graupel, and some freezing drops, suggesting that the occurrence of high ice number concentrations was likely related to the Hallett–Mossop mechanism, although many other ice multiplication processes cannot be totally ruled out.The maximum ice number concentration obtained during the first penetration was around two to three orders of magnitude larger than that predicted by the Demott and Fletcher schemes when assuming the cloud top temperature was around-15℃.During the second penetration conducted within the stratiform cloud, N_（100） and N_（500） decreased by a factor of five to ten, and the presence of columnar and needle-like crystals became very rare.
基金supported by the National Natural Science Foundation of China (Grant No. 40805056)the National Key Technologies R&D Program of China (Grant No. 2006BAC12B00)
文摘The microphysical "three-layer" model for stratiform clouds over a midlatitude location in Northwest China is investigated by combining in situ airborne Particle Measuring Systems, Inc. (PMS), radar measurements, and the NCAR/Penn State Mesoscale Model Version 5 (MM5) simulation with a two-moment microphysics scheme. The coexistence of measured supercooled liquid water and small ice particles produces snow particles below the cloud top in the second layer. Peak number concentration and mean diameter of cloud water and raindrop appear in the third warm layer. A thin dry layer just below the melting layer is also observed. The predicted precipitation is tested by equitable threat score. The melting layer is clearly defined in the radar image and model radar reflectivity output is agreement with the observations. The model results provide features of the microphysical structure for every layer of "three-layer" model at Yan'an station. For both observation and model simulation, the "three-layer" model explains the stratiform precipitation formation completely and comprehensively.
基金This work was supported by fund from the National Scientific Foundation of China
文摘The rainout-removal of SO2 and the acidification of precipitation from stratiform clouds are simulated using a one-dimensional, time-dependent model, parameterized microphysically in which dissolution and dissociation of gaseous SO2 and H2O2, and oxidation reaction in aqueous phase are taken into account. The effects of dynamic factors, including updraft flow and turbulent transport, and the concentration of gaseous SO2 and H2O2 being transported into the clouds on pH value of the precipitation, the conversion rate S(Ⅳ)-S(Ⅵ) and the wet deposition rate of SO2 are discussed.
基金jointly supported by the National Natural Science Foundation of China (Grant Nos. 91437219, 91637312 and 91637101)the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (Grant No. QYZDY-SSWDQC018)The CloudSat/CALIPSO data were obtained from the CloudSat Data Processing Center (http://www.cloudsat.cira. colostate.edu/order-data) funded by NASA’s CloudSat project
文摘Cloud is essential in the atmosphere, condensing water vapor and generating strong convective or large-scale persistent precipitation. In this work, the relationships between cloud vertical macro- or microphysical properties, radiative heating rate, and precipitation for convective and stratiform clouds in boreal summer over the Tibetan Plateau (TP) are analyzed and compared with its neighboring land and tropical oceans based on CloudSat/CALIPSO satellite measurements and TRMM precipitation data. The precipitation intensity caused by convective clouds is twofold stronger than that by stratiform clouds. The vertical macrophysics of both cloud types show similar features over the TP, with the region weakening the precipitation intensity and compressing the cloud vertical expansion and variation in cloud top height, but having an uplift effect on the average cloud top height. The vertical microphysics of both cloud types under conditions of no rain over the TP are characterized by lower-level ice water, ice particles with a relatively larger range of sizes, and a relatively lower occurrence of denser ice particles. The features are similar to other regions when precipitation enhances, but convective clouds gather denser and larger ice particles than stratiform clouds over the TP. The atmospheric shortwave (longwave) heating (cooling) rate strengthens with increased precipitation for both cloud types. The longwave cooling layer is thicker when the rainfall rate is less than 100 mm d?1, but the net heating layer is typically compressed for the profiles of both cloud types over the TP. This study provides insights into the associations between clouds and precipitation, and an observational basis for improving the simulation of convective and stratiform clouds over the TP in climate models.
基金Supported by National Natural Science Fund(41475121)Science and Technology Plan Item of Hebei Province(17227001D)
文摘An aircraft precipitation operation and detecting was implemented by Hebei Weather Modification Office over Shijiazhuang City during18:18-19:37 on April 2,2014. The detecting area was near 500 hP a of high-altitude trough and surface inverted trough. Slight shower had appeared in Tianjin( rear of inverted trough) and Shanxi Province( near the inverted trough) at 20:00,while there was not precipitation in Hebei Province which was near the inverted trough. Analysis showed that the water vapor supply was not enough below 550 hP a in south-central Hebei Province,and cloud system development condition was poor. The cold cloud developed better,but there was not warm cloud,causing no precipitation on the ground.
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.
文摘We introduced the two-parameter stratiform cloud model of Hu and Yan (1986) into the mesoscale model ofAnthes et al. (1987), and reprogramed the latter, then constructed a three-dimensional stratiform cloud system modelwhich includes three phases of water and detailed cloud physical processes. For the stability and accuracy of calculationin a larger time step, we accepted a set of hybrid-schemes for all and the time split scheme for some of the cloud physicalprocesses, and proposed a parameterized method which calculates different types of phase change processessimultaneously, and designed the falling schemes of particles following the Lagrangian method.We used a dry model, a cumulus parameterization model, a two-phase explicit scheme model, and the model pres-ented here to simulate two low-level mesoscale vortices, compared and analysed the simulating capability of these mod-els. The results show that in simulation of the circulation structure of meso-vortex, the structure of cloud system, andsurface precipitation, the model presented here is more reasonable and closer to the observations than other models.
文摘A 2-D slab-symmetric model of mixed convective-stratiform cloud is developed by superimposing convective cloud-size field on the convergence field,in order to simulate and study the mixed clouds consisting of stratiform cloud and convective cloud.A deep convective,anelastic and conservative system of equations with basic variables(V,θ,π')is solved by a new method to calculate dynamic field.The water substance in the cloud is divided into 6 categories and the microphysical processes are described in spectrum with two variable parameters and more reasonable particle number/size distributions.To compare with measured radar echo intensity and structure,the model may calculate echo intensity of the model cloud observed by radar.
基金jointly supported by the National Natural Science Foundation of China[Grant Nos.U2342202 and 42175005]the Qing Lan Project[Grant No.R2023Q06]。
文摘This study investigates the characteristics of secondary eyewall formation(SEF)in idealized tropical cyclones embedded in vertical wind shear(VWS)at different heights.The results show that upper-layer VWS at a relatively low shear height is more favorable for SEF than upper-layer VWS at a relatively high shear height and lowerlayer VWS.In the experiments with upper-layer VWS at a relatively low shear height,better-organized stratiform clouds are located in the downwind sector of outer rainbands.The low-level descending inflow associated with the stratiform sector is stronger in these experiments than in the experiments with upper-layer VWS at a relatively high shear height and lower-layer VWS.The enhanced descending inflow can trigger supergradient winds and convergence near the top of the boundary layer,close to three times the radius of the maximum wind,where convection is locally forced.The subsequent convection axisymmetrization leads to SEF.
