Weather forecasting is crucial for agriculture,transportation,and industry.Deep Learning(DL)has greatly improved the prediction accuracy.Among them,Graph Neural Networks(GNNs)excel at processing weather data by establ...Weather forecasting is crucial for agriculture,transportation,and industry.Deep Learning(DL)has greatly improved the prediction accuracy.Among them,Graph Neural Networks(GNNs)excel at processing weather data by establishing connections between regions.This allows them to understand complex patterns that traditional methods might miss.As a result,achieving more accurate predictions becomes possible.The paper reviews the role of GNNs in short-to medium-range weather forecasting.The methods are classified into three categories based on dataset differences.The paper also further identifies five promising research frontiers.These areas aim to boost forecasting precision and enhance computational efficiency.They offer valuable insights for future weather forecasting systems.展开更多
The raindrop size distribution(DSD) is a significant characteristic of precipitation physics,which plays a crucial role in improving the accuracy of radar quantitative precipitation estimation and prediction.There is ...The raindrop size distribution(DSD) is a significant characteristic of precipitation physics,which plays a crucial role in improving the accuracy of radar quantitative precipitation estimation and prediction.There is an effect of atmospheric circulation and weather sy stems in South China,with frequent precipitation and differences in regional features,resulting in a limited understanding of the DSD characteristics and their impact mechanisms in the region. In this study,six ground-based two-dimensional video di sdrometers(2DVDs) were used to analyze the DSD of inland and coastal in South China during the five-year(2016-2020) monsoon seasons(April to September),ERA5 reanalysis data and MODIS cloud property products were also used to investigate the dynamics and microphysical characteristics of monsoon precipitation.Compared to inland rainfall,coastal rainfall has a higher conentration of small,medium,and diameter of less than 4.7 mm large raindrops.Considering the contributions to precipitation,the inland and coastal rainfall are dominated by convective rain,accounting for 74.8% and 84.7% of the total rainfall,respectively.The coastal rainfall has a higher the mass-weiglited mean diameter(D_(m)) value than the inland rainfall D_(m) for both the stratiform and convective rainfall.The logarithmic mean of the generalized intercept parameter(log_(10)N_(w)) in inland stratiform rain is greater than that in coastal areas,while convective rain is relatively small.Due to the impact of precipitation types and climate conditions,The Z-R relationship between inland and coastal rainfall also shows obvious differences.Compared to inland areas,there is more frequent convective activity,relatively moist near-surface conditions,and lower cloud droplet number concentrations,which contribute to larger D_(m) of raindrops in coastal areas.This study deepens the understanding of changes in South China's coastal and inland DSD and provides support for improving numerical weather forecasting in the region.展开更多
Cloud type profoundly affects precipitation,but few studies have explored its impact on precipitation scale height.The authors calculated the ratio of the volume of each cloud type to the total cloud volume and partit...Cloud type profoundly affects precipitation,but few studies have explored its impact on precipitation scale height.The authors calculated the ratio of the volume of each cloud type to the total cloud volume and partitioned the tropical region based on the dominant cloud types.Based on this,tropical regions were categorized into altocumulus control regions,stratocumulus control regions,deep convective cloud control regions,and transition regions.These regions exhibit unique characteristics:high precipitation scale heights and low surface precipitation rates in altocumulus control regions;low precipitation scale heights and low surface precipitation rates in stratocumulus control regions;and moderate precipitation scale heights with high surface precipitation rates in deep convective cloud regions.These features arise from differences in cloud characteristics,precipitation probability,and intensity,influenced by varying water vapor structures.In terms of physical mechanisms,altocumulus,stratocumulus,and deep convective cloud regions are characterized by total dryness,upper-level dryness with lower-level wetness,and total wetness,respectively.Upper-layer dryness leads to low cloud and precipitation structures,reducing the precipitation scale height,while lower-layer dryness increases it.Different humidity conditions in the upper and lower layers lead to variations in cloud type and volume distribution,ultimately affecting precipitation scale heights.This finding aids the mechanistic study of cloud precipitation physics in the tropics,providing valuable insights for developing numerical models and parameterizations.展开更多
The ice-phase microphysical characteristics of a stratiform cloud system over the Qilian Mountains in northwestern China on 15 September 2022 were analyzed via aircraft data.The stratiform cloud system developed under...The ice-phase microphysical characteristics of a stratiform cloud system over the Qilian Mountains in northwestern China on 15 September 2022 were analyzed via aircraft data.The stratiform cloud system developed under southwesterly flows at 500 hPa and was affected locally by topography.Synoptic features and aircraft observations revealed strengthened cloud development on the leeward slope.The ice particle habits and microphysical processes at heights of 6-8 km were investigated.The cloud system was characterized by extremely low supercooled liquid water content at temperatures between−4℃ and−17℃.The ice particle concentrations ranged predominantly from 10 to 30 L^(−1),corresponding to ice water content ranging from 0.01 to 0.05 g m^(−3).Active ice aggregation was observed at temperatures colder than−10°C.The windward side of the cloud system exhibited weaker development and two distinct cloud layers.Intense orographic uplift on the leeward slope enhanced ice particle aggregation.The clouds on the leeside presented lower ice particle concentrations but larger sizes than those on the windward side.The influence of aggregation on the ice particle size distribution was reflected in two main aspects.One aspect was the bimodal spectra at−16℃,with the first peak at 125μm and subpeak at 400-500μm;the other was the broadened size spectra at−13℃ due to significant aggregation of dendrites.展开更多
The extraordinary Super Typhoon(STY)Muifa(2022)made landfall four times and had a significant impact on the coastal regions from south to north of China.Although previous studies have demonstrated the‘pumping effect&...The extraordinary Super Typhoon(STY)Muifa(2022)made landfall four times and had a significant impact on the coastal regions from south to north of China.Although previous studies have demonstrated the‘pumping effect'of typhoons on the enhancement of reactive nitrogen(Nr)wet deposition over the ocean,it is uncertain how Nr deposition is influenced by typhoons thatmake prolonged mechanism due tomultiple landfalls.In this study,theNr wet deposition induced by STYMuifawas investigated fromthe perspective of in-and below-cloud processes based on the Nested Air Quality Prediction Modeling System with an online tracer-tagging module.High volume of Nr wet deposition caused by Muifa migrated from south to north,passing over half of China's coastal cities.Compared to the typhoon generated vicinity,both mean values of the oxidized and reduced nitrogen wet deposition over the Typhoon affected regions were increased about 20.4 and 66.1 times after landfall even with the similar rainfall.Emissions from the four landfall areas of China contributed to the majority of Nr wet deposition with significantly enhanced proportion of in-cloud deposition.The strong pumping effect of typhoon to the Nr deposition along the coastal areas and the risk of ecosystem effects requires further researches and higher demands on the control of nitrogen emissions of National Industrial Park,which usually located in China's coastal cities.展开更多
In recent years,the Cloud Imaging Probe(CIP)and Precipitation Imaging Probe(PIP)produced by Droplet Measurement Technologies(DMT)have been introduced by a number of meteorological research and operation centers in Chi...In recent years,the Cloud Imaging Probe(CIP)and Precipitation Imaging Probe(PIP)produced by Droplet Measurement Technologies(DMT)have been introduced by a number of meteorological research and operation centers in China.The supporting software provided by DMT,i.e.,PADS(Particle Analysis and Display System),cannot output detailed information on each individual particle,which definitely limits the in-depth utilization of cloud and precipitation particle image data in China.In this paper,particle-by-particle information was extracted by decompressing the CIP and PIP original particle image data,based on which a new definition of the dimension for nonspherical particles is proposed by using the area of the convex hull enclosing a particle to obtain the equivalent diameter of a circle with equal area.Based on the data detected during one flight in Inner Mongolia,the particle size distribution obtained using the new particle size definition and that used by the other four existing definitions are compared.The results show that the particle number concentration calculated using different particle size definitions can vary by up to an order of magnitude.The result obtained based on the new particle size definition is closest to that calculated with the area-equivalent diameter definition.展开更多
Efficient activation of molecular oxygen(O_(2))is considered a promising technique for the removal of antibiotics.However,how to effectively regulate electrons distribution to promote O_(2)activation remains a challen...Efficient activation of molecular oxygen(O_(2))is considered a promising technique for the removal of antibiotics.However,how to effectively regulate electrons distribution to promote O_(2)activation remains a challenge at present.In this study,phosphorus and sodium co-doped carbon nitride(PNaCN)were designed to rearrange the electrons distribution to activate O_(2)for the degradation of tetracycline.The generation of·O_(2)~-was innovatively observed via in-situ O_(2)fitting Fourier transform infrared(FTIR)spectroscopy,demonstrating the outstanding O_(2)activation ability of PNa5.Density functional theory(DFT)further confirmed that the rational co-doping led to the rearrangement of local electrons,resulting in electron-rich Na sites and electron-deficient P sites.These sites exhibited greater susceptibility to O_(2)adsorption and charge transfer.Besides,the degradation rate of tetracycline was increased by 2.44 times using co-doped CN.This study provides a new inspiration for enhancing O_(2)activation by inducing electrons rearrangement.展开更多
To evaluate the ability of the Predicted Particle Properties(P3)scheme in the Weather Research and Forecasting(WRF)model,we simulated a stratiform rainfall event over northern China on 22 May 2017.WRF simulations with...To evaluate the ability of the Predicted Particle Properties(P3)scheme in the Weather Research and Forecasting(WRF)model,we simulated a stratiform rainfall event over northern China on 22 May 2017.WRF simulations with two P3 versions,P3-nc and P3-2ice,were evaluated against rain gauge,radar,and aircraft observations.A series of sensitivity experiments were conducted with different collection efficiencies between ice and cloud droplets.The comparison of the precipitation evolution between P3-nc and P3-2ice suggested that both P3 versions overpredicted surface precipitation along the Taihang Mountains but underpredicted precipitation in the localized region on the leeward side.P3-2ice had slightly lower peak precipitation rates and smaller total precipitation amounts than P3-nc,which were closer to the observations.P3-2ice also more realistically reproduced the overall reflectivity structures than P3-nc.A comparison of ice concentrations with observations indicated that P3-nc underestimated aggregation,whereas P3-2ice produced more active aggregation from the self-collection of ice and ice-ice collisions between categories.Efficient aggregation in P3-2ice resulted in lower ice concentrations at heights between 4 and 6 km,which was closer to the observations.In this case,the total precipitation and precipitation pattern were not sensitive to riming.Riming was important in reproducing the location and strength of the embedded convective region through its impact on ice mass flux above the melting level.展开更多
Temperature has a substantial impact on the emission of biogenic volatile organic compounds(BVOCs).Moder-ate warm temperatures,e.g.,30–40°C,could boost plant metabolism,increasing BVOC emissions.Against the back...Temperature has a substantial impact on the emission of biogenic volatile organic compounds(BVOCs).Moder-ate warm temperatures,e.g.,30–40°C,could boost plant metabolism,increasing BVOC emissions.Against the backdrop of global warming,plants emit more BVOCs to cope with thermal stress,leading to elevated concen-trations of tropospheric ozone(O_(3))and secondary organic aerosols(SOA).In recent years,a considerable body of research has explored the interaction between tree species and BVOCs under the influence of various environ-mental factors.Although many studies have examined explored the temperature dependence of BVOC emissions in the past,few studies have conducted a comprehensive and in-depth investigation into the impacts of tempera-ture.This review summarizes the relevant studies on BVOCs in the past decade,including the main biosynthetic pathways,emission observation techniques and emission inventories,as well as how temperature affects isoprene and monoterpene emission rates and the formation of O_(3) and SOA.Our work offers a theoretical foundation and guidance for future efforts to advance the comprehension of BVOC emission characteristics and develop strategies to mitigate secondary pollution.展开更多
Previous satellite observations have identified the appearance of“cloud trough”(or“cloud trench”),with cloud tops visually collapsed following airborne cloud seeding operation,demonstrating the effect of weather m...Previous satellite observations have identified the appearance of“cloud trough”(or“cloud trench”),with cloud tops visually collapsed following airborne cloud seeding operation,demonstrating the effect of weather modification.However,refined observations of troughed clouds and associated microphysical processes are still notably scarce,especially those obtained via in-situ aircraft measurements.In this study,variations in cloud microphysics associated with and without troughed clouds along an airborne stratiform cloud seeding path over central China on 15 December 2019 are analyzed and compared based on aircraft measurements,ground-based radar observations,and FY-4A satellite imagery.The results are as follows.(1)The troughed clouds were mainly formed to the northeast of the flight path and were observed only in some parts of the seeded stratiform clouds.The seeding tracks became visible starting from 60 min after seeding and persisted for approximately 3 h,covering a maximum width of 30–40 km in FY-4A imagery.Radar echo enhancements can be observed by a ground-based radar at some parts of the seeding tracks.(2)The troughed clouds were observed only when the ambient air temperature(T)was≤-7℃,a condition favoring high nucleation efficiency of silver iodide(Ag I)aerosols,whereas no cloud troughs formed at higher temperatures.(3)The troughed clouds with strong radar echoes(i.e.,large precipitation)corresponded to regions with high values(>0.1 g m^(-3))of supercooled water content after cloud seeding,which facilitated the growth of precipitation particles.(4)Within the troughed clouds,the cloud optical thickness and cloud top height decreased,while the effective radii of cloud particles increased by nearly 10μm.These results provide valuable guidance for optimizing cold cloud seeding conditions in artificial rainfall enhancement.Meanwhile,the presence of high supercooled water content,particularly the threshold of supercooled water content,is a critical factor for strong precipitation,which necessitates further studies.展开更多
Raindrop size distribution(DSD)is crucial in the study of precipitation microphysics,but the parameters that characterize the DSD is not easy to be derived accurately.Wind profile radar(WPR)provides rich data with hig...Raindrop size distribution(DSD)is crucial in the study of precipitation microphysics,but the parameters that characterize the DSD is not easy to be derived accurately.Wind profile radar(WPR)provides rich data with high spatiotemporal resolution and low attenuation,and the previous studies using WPR power spectral distribution to extract DSD parameters demonstrate certain limitations.In this study,a WPR-based Gamma DSD parameter estimation network(WPR-DSDnet)combined with a neural network(NN)and a long short-term memory(LSTM)network is designed,and then a WPR-DSDnet-based model is trained to retrieve the Gamma DSD parameters including normalized intercept parameter(N_(w))and mass-weighted average diameter(D_(m))by means of the high-resolution WPR reflectivity factor and velocity spectral width as the inputs,and the spatiotemporal matching disdrometer data collected from 2017 to 2021 in Beijing as labels.Two precipitation cases are used to validate the performance of the model,and the results demonstrate that the model can retrieve the Gamma DSD parameters effectively,in which the ratio between the estimated and measured values of both lg N_(w)and D_(m)exceeds 99%.The estimation accuracy of lg N_(w)is slightly better than that of D_(m)due to smaller relative deviation of lg N_(w)although the absolute deviation between the estimated and true values of lg N_(w)is larger than that of D_(m),which are probably caused by the larger distribution range of lg N_(w).The vertical distributions of lg N_(w)closely aligns with variations in precipitation intensity,which hints it is a useful indicator for precipitation intensity change.On the other hand,the distribution of D_(m)is closely associated with the degree of convection,which is valuable for precipitation recognition and classification.The two parameters extracted by the deep learning-based model can facilitate further in-depth analysis on precipitation characteristics and mechanisms with WPR data.展开更多
Cloud water plays an important role in the global atmospheric water cycle and weather modification,but cloud is one of the most uncertain parameters in the study of weather and climate.The cloud water products from di...Cloud water plays an important role in the global atmospheric water cycle and weather modification,but cloud is one of the most uncertain parameters in the study of weather and climate.The cloud water products from different data sources may have considerable discrepancies.In this study,the total cloud liquid water(termed as cloud liquid water path,LWP)obtained from satellite observations[Advanced Himawari Imager(AHI)and Advanced Microwave Scanning Radiometer(AMSR)]and three sets of modern reanalysis data(ERA5,JRA-55,and MERRA-2)are compared and analyzed.Moreover,characteristics of vertical distributions of cloud liquid water content(LWC)in different regions over East Asia are analyzed by using the profile data from the reanalyses.The main findings are as follows:(1)in extensive warm marine clouds,AHI and AMSR have a good agreement(with the correlation coefficient larger than 0.7)but with an overestimation from AHI;(2)under warm cloud conditions,the LWP in ERA5shows a significant positive bias(about 0.065 kg m^(-2))over land,while MERRA-2 is closer to the satellite product compared with ERA5 and JRA-55;and(3)Southwest China(SW)is the area with most abundant LWC.The LWC is mainly concentrated in the middle and lower troposphere in the study area,and the LWC in ERA5 is higher than that in MERRA-2 and JRA-55.Overall,satellite observations and reanalyses exhibit significant inconsistency for cloud LWP,which needs further investigation and understanding.展开更多
Cloud effective radius(CER)is a fundamental microphysical property of clouds,critical for understanding cloud formation and radiative effects.Satellite spectral imagers,widely utilized in passive remote sensing,facili...Cloud effective radius(CER)is a fundamental microphysical property of clouds,critical for understanding cloud formation and radiative effects.Satellite spectral imagers,widely utilized in passive remote sensing,facilitate the monitoring of cloud characteristics,including CER,over extended time periods and spatial scales.Various observational methods have been employed to evaluate satellite cloud property products;however,in situ measurement evaluations of CER remain limited,particularly for products over China.This study utilized aircraft observations provided by the China Meteorological Administration Weather Modification Centre to evaluate the CER retrieved by Fengyun-4A Advanced Geosynchronous Radiation Imager(AGRI)and Himawari-8 Advanced Himawari Imager(AHI).Three flights were selected from the aircraft dataset for evaluation,involving flights through non-precipitating stratiform clouds with stable,high-quality measurements.Rigorous data selection and collocation procedures were employed to ensure a comprehensive comparison.Satellite retrievals from heterogeneous cloud fields were excluded,and representative in-cloud aircraft measurements were identified through multi-parameter filtering.The flight trajectory was adjusted to account for horizontal cloud movement corresponding to time differences between observations from different platforms.Additionally,in situ measurements from different vertical layers were adjusted to a comparable position near the cloud top.Results indicate that CER retrieved from satellites is generally overestimated compared to in situ measurements.For AGRI,the average difference(AD)is 2.90μm,with a root mean square difference(RMSD)of 3.53μm.For AHI,the AD is 2.92μm,and the RMSD is 3.59μm.To enhance future validation and evaluation of remote sensing results,factors such as instrument calibration,flight patterns,and cloud conditions will be carefully considered.Increasing the number of cases should further reduce errors associated with individual instances,enabling more precise assessments.展开更多
The airborne two-dimensional stereo(2D-S) optical array probe has been operating for more than 10 yr, accumulating a large amount of cloud particle image data. However, due to the lack of reliable and unbiased classif...The airborne two-dimensional stereo(2D-S) optical array probe has been operating for more than 10 yr, accumulating a large amount of cloud particle image data. However, due to the lack of reliable and unbiased classification tools,our ability to extract meaningful morphological information related to cloud microphysical processes is limited. To solve this issue, we propose a novel classification algorithm for 2D-S cloud particle images based on a convolutional neural network(CNN), named CNN-2DS. A 2D-S cloud particle shape dataset was established by using the 2D-S cloud particle images observed from 13 aircraft detection flights in 6 regions of China(Northeast, Northwest, North,East, Central, and South China). This dataset contains 33,300 cloud particle images with 8 types of cloud particle shape(linear, sphere, dendrite, aggregate, graupel, plate, donut, and irregular). The CNN-2DS model was trained and tested based on the established 2D-S dataset. Experimental results show that the CNN-2DS model can accurately identify cloud particles with an average classification accuracy of 97%. Compared with other common classification models [e.g., Vision Transformer(ViT) and Residual Neural Network(ResNet)], the CNN-2DS model is lightweight(few parameters) and fast in calculations, and has the highest classification accuracy. In a word, the proposed CNN-2DS model is effective and reliable for the classification of cloud particles detected by the 2D-S probe.展开更多
Understanding the characteristics of cloud water resource(CWR)and precipitation efficiency of hydrometeors(PEh)is imperative for the application of CWR in Northwest China.The atmospheric precipitable water(PW)in all f...Understanding the characteristics of cloud water resource(CWR)and precipitation efficiency of hydrometeors(PEh)is imperative for the application of CWR in Northwest China.The atmospheric precipitable water(PW)in all four seasons and clouds and PEh in summer were studied with ERA-5 and CloudSat data in this region.The results show that topography,especially in the Tibetan Plateau,exerts significant impacts on the precipitation and PW in summer,since large amounts of clouds are distributed along the mountain ranges.The study region is divided into four typical areas:the monsoon area in eastern Northwest China(NWE),the Qilian Mountains area(QM),the Tianshan Mountains area(TM),and the Source of Three Rivers area(STR).Over the four areas,cloud top height(6.3 km)and cloud base height(3.3 km)over NWE are higher,and precipitating clouds are thicker(7 km)in the single-layer clouds.Liquid water content decreases with increasing altitude,while the ice water content first increases and then decreases.Liquid water path is higher over NWE(0.11 kg m^(−2))than over TM and STR(0.05 kg m^(−2)),and the ice water path is mainly concentrated within the range of 0.025–0.055 kg m^(−2).The PEh values are distributed unevenly and affected evidently by the terrain.Although the PEh values in the four typical areas(0.3–0.6)are higher than those in other regions,the CWR is relatively abundant and has a higher exploitation potential.Therefore,it is well-founded to exploit CWR for alleviating water shortages in these areas of Northwest China in summer.展开更多
This study investigated the cloud microphysical processes and atmospheric water budget during the extreme precipitation event on 20 July 2021 in Zhengzhou of Henan Province,China,based on observations,reanalysis data,...This study investigated the cloud microphysical processes and atmospheric water budget during the extreme precipitation event on 20 July 2021 in Zhengzhou of Henan Province,China,based on observations,reanalysis data,and the results from the high-resolution large-eddy simulation nested in the Weather Research and Forecasting(WRF)model with assimilation of satellite and radar observations.The results show that the abundant and persistent southeasterly supply of water vapor,induced by Typhoons In-Fa and Cempaka,under a particular synoptic pattern featured with abnormal northwestward displacement of the western Pacific subtropical high,was conducive to warm rain processes through a high vapor condensation rate of cloud water and an efficient collision–coalescence process of cloud water to rainwater.Such conditions were favorable for the formation and maintenance of the quasi-stationary warmsector heavy rainfall.Precipitation formation through the collision–coalescence process of cloud water to rainwater accounted for approximately 70%of the total,while the melting of snow and graupel accounted for only approximately 30%,indicating that warm cloud processes played a dominant role in this extreme rainfall event.However,enhancement of cold cloud processes promoted by latent heat release also exerted positive effect on rainfall during the period of most intense hourly rainfall.It was also found that rainwater advection from outside of Zhengzhou City played an important role in maintaining the extreme precipitation event.展开更多
To explore the key technologies of artificial weather modification for specific targets(e.g.,a stadium)and improve the efficiency of artificial rainfall modification for major events,this study conducts an artificial ...To explore the key technologies of artificial weather modification for specific targets(e.g.,a stadium)and improve the efficiency of artificial rainfall modification for major events,this study conducts an artificial rainfall reduction experiment for the closing ceremony of Nanjing Youth Olympic Games on 28 August 2014.Satellite retrievals,radar observations,sounding data,and other sources of information as well as Cloud and Precipitation Accurate Analysis System(CPAS)are used in this study.The main conclusions are as follows.(1)On 28 August 2014,a large-scale cumulus cloud system with mixed-phase stratocumulus and stratus precipitation was observed.This system was influenced by the weak shear of a low-level trough and the precipitation was dominated by cold clouds with dry layers between clouds.Thereby,we adopted the crystal-priming over-catalytic hypothesis and conducted a rocket-catalytic rain abatement operation at a certain distance(100–25 km)from the stadium.Rocket shootings of different intensities were implemented for two echoes that affected the stadium successively(two rounds of 15 rocket shootings within15 min for an isolated weak echo IA;multiple rounds of 156 rocket shootings within 80 min for a strong echo IB).Amazingly,after the shootings with the catalysis in the air,reflectivity of the two echoes was reduced at all altitudes with the most significant reduction at the 2-km altitude,and the time needed for the obvious reduction was 40 min.The most obvious reduction of the two echoes then maintained for 60 and 53 min,respectively,and the operation time needed for the echo zone to recover after the stop of rocket shooting was 108 min for echo IA and 90 min for echo IB.The two echoes moving across the stadium during the time period of the closing ceremony(2000–2130 local time)were at their minimal strengths,with almost no echo over the target stadium.This demonstrates that the rocket shooting strategy of over-crystallization catalysis is effective,and the shooting site,time,and dose are reasonable.The following technical parameters were used during this experiment.At about 80–25 km away from the target stadium in the west,the rocket shooting lasted for 15–80 min and the doses were not less than 1 shot min~(-1)(1 shot min~(-1)for echo IA,2.25 shots min~(-1)for echo IB).The attenuation rate was 0.21 dBZ min~(-1)for the average 15 dBZ of echo IA.For the average 25 dBZ of echo IB,the attenuation rate was 0.27 dBZ min~(-1).The above technical settings helped achieve the goal of reducing rain over the stadium to almost zero for nearly 1-h period during the critical time of the event.展开更多
In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding catalysts.Our objective was to elucidate the mech...In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding catalysts.Our objective was to elucidate the mechanism of snowfall enhancement in stratiform clouds in the Bayanbulak test area of Xinjiang,China.The results indicated that the optimal seeding time was the early stages of weather system development.In this case,the optimal seeding zone was identified as the northwest of the test area,especially near the cloud top(altitudes between 3500 and 4000 m,temperatures range−11 to−15℃),and the ideal concentration of catalyst was with ice crystal density of 1.0×10^(7)kg^(−1)within the target area.Under such conditions,the total precipitation rate in the seeding-affected area increased to 50.1 mm h^(−1).The results also showed that the favorable seeding region was featured by high content of supercooled water and low population of natural ice crystals,where artificial ice crystals could substantially increase the snowfall.This augmentation typically appeared in a unimodal pattern,with the peak formed within 2–3 h after seeding.Seeding in the ice–water mixed zone of a supercooled cloud facilitated rapid ice crystal growth to snow-flake pieces via the Bergeron process,which in turn consumed more supercooled water via collision–coalescence with cloud water droplets.Simultaneously,the intensive consumption of supercooled water impeded the riming process and reduced the formation of graupel particles within the cloud.The dispersion of artificial ice crystals extended over tens of kilometers horizontally;however,in the vertical direction most particles remained approximately 1 km below the seeding layer,due to limited vertical ascent rate in the stratiform clouds restricting upward movement of artificial ice crystals.The above results help better understand the snowfall enhancement mechanism in stratiform clouds and facilitate related weather modification practice.展开更多
基金supported by Key Laboratory of Smart Earth(KF2023ZD03-05)CMA Innovative and Development Program(CXFZ.20231035)+2 种基金National Key R&D Program of China(No.2021ZD0111902)National Natural Science Foundation of China(Nos.62472014,U21B2038)the Scientific and Technological Project of China Meteorological Administration(CMAJBGS202505).
文摘Weather forecasting is crucial for agriculture,transportation,and industry.Deep Learning(DL)has greatly improved the prediction accuracy.Among them,Graph Neural Networks(GNNs)excel at processing weather data by establishing connections between regions.This allows them to understand complex patterns that traditional methods might miss.As a result,achieving more accurate predictions becomes possible.The paper reviews the role of GNNs in short-to medium-range weather forecasting.The methods are classified into three categories based on dataset differences.The paper also further identifies five promising research frontiers.These areas aim to boost forecasting precision and enhance computational efficiency.They offer valuable insights for future weather forecasting systems.
基金National Natural Science Foundation of China(U2242203, 41975138, 42075086, 42275008)Guangdong Basic and Applied Basic Research Foundation (2023A1515011971)Science Technology Research Program of Guangdong Meteorological Service (GRMC2021Q01)。
文摘The raindrop size distribution(DSD) is a significant characteristic of precipitation physics,which plays a crucial role in improving the accuracy of radar quantitative precipitation estimation and prediction.There is an effect of atmospheric circulation and weather sy stems in South China,with frequent precipitation and differences in regional features,resulting in a limited understanding of the DSD characteristics and their impact mechanisms in the region. In this study,six ground-based two-dimensional video di sdrometers(2DVDs) were used to analyze the DSD of inland and coastal in South China during the five-year(2016-2020) monsoon seasons(April to September),ERA5 reanalysis data and MODIS cloud property products were also used to investigate the dynamics and microphysical characteristics of monsoon precipitation.Compared to inland rainfall,coastal rainfall has a higher conentration of small,medium,and diameter of less than 4.7 mm large raindrops.Considering the contributions to precipitation,the inland and coastal rainfall are dominated by convective rain,accounting for 74.8% and 84.7% of the total rainfall,respectively.The coastal rainfall has a higher the mass-weiglited mean diameter(D_(m)) value than the inland rainfall D_(m) for both the stratiform and convective rainfall.The logarithmic mean of the generalized intercept parameter(log_(10)N_(w)) in inland stratiform rain is greater than that in coastal areas,while convective rain is relatively small.Due to the impact of precipitation types and climate conditions,The Z-R relationship between inland and coastal rainfall also shows obvious differences.Compared to inland areas,there is more frequent convective activity,relatively moist near-surface conditions,and lower cloud droplet number concentrations,which contribute to larger D_(m) of raindrops in coastal areas.This study deepens the understanding of changes in South China's coastal and inland DSD and provides support for improving numerical weather forecasting in the region.
基金supported by the National Natural Science Foundation of China[grant numbers 42175099 and 42027804]The appointment of Chunsong Lu at Nanjing University of Information Science&Technology was partially supported by the Jiangsu Specially-Appointed Professor[grant number R2024T01].
文摘Cloud type profoundly affects precipitation,but few studies have explored its impact on precipitation scale height.The authors calculated the ratio of the volume of each cloud type to the total cloud volume and partitioned the tropical region based on the dominant cloud types.Based on this,tropical regions were categorized into altocumulus control regions,stratocumulus control regions,deep convective cloud control regions,and transition regions.These regions exhibit unique characteristics:high precipitation scale heights and low surface precipitation rates in altocumulus control regions;low precipitation scale heights and low surface precipitation rates in stratocumulus control regions;and moderate precipitation scale heights with high surface precipitation rates in deep convective cloud regions.These features arise from differences in cloud characteristics,precipitation probability,and intensity,influenced by varying water vapor structures.In terms of physical mechanisms,altocumulus,stratocumulus,and deep convective cloud regions are characterized by total dryness,upper-level dryness with lower-level wetness,and total wetness,respectively.Upper-layer dryness leads to low cloud and precipitation structures,reducing the precipitation scale height,while lower-layer dryness increases it.Different humidity conditions in the upper and lower layers lead to variations in cloud type and volume distribution,ultimately affecting precipitation scale heights.This finding aids the mechanistic study of cloud precipitation physics in the tropics,providing valuable insights for developing numerical models and parameterizations.
基金supported by the National Natural Science Foundation of China(Grant Nos.42475100 and 42405091)supported by the CMA Key Innovation Team(Grant No.CMA2022ZD10)+1 种基金the CMA Weather Modification Centre Innovation Team(Grant No.WMC2023IT02)the National Key R&D Program of China(Grant No.2019YFC1510305).
文摘The ice-phase microphysical characteristics of a stratiform cloud system over the Qilian Mountains in northwestern China on 15 September 2022 were analyzed via aircraft data.The stratiform cloud system developed under southwesterly flows at 500 hPa and was affected locally by topography.Synoptic features and aircraft observations revealed strengthened cloud development on the leeward slope.The ice particle habits and microphysical processes at heights of 6-8 km were investigated.The cloud system was characterized by extremely low supercooled liquid water content at temperatures between−4℃ and−17℃.The ice particle concentrations ranged predominantly from 10 to 30 L^(−1),corresponding to ice water content ranging from 0.01 to 0.05 g m^(−3).Active ice aggregation was observed at temperatures colder than−10°C.The windward side of the cloud system exhibited weaker development and two distinct cloud layers.Intense orographic uplift on the leeward slope enhanced ice particle aggregation.The clouds on the leeside presented lower ice particle concentrations but larger sizes than those on the windward side.The influence of aggregation on the ice particle size distribution was reflected in two main aspects.One aspect was the bimodal spectra at−16℃,with the first peak at 125μm and subpeak at 400-500μm;the other was the broadened size spectra at−13℃ due to significant aggregation of dendrites.
基金supported by the National Natural Science Foundation of China(Nos.42122049 and 42377104)the Basic Strengthening Research Program(No.2021-JCJQ-JJ-1058)+1 种基金the Strategy Priority Research Programof Chinese Academy of Sciences(No.XDB0760403)the National Key Scientific and Technological Infrastructure project"Earth System Science Numerical Simulator Facility"(EarthLab)the Innovation Foundation of CPML/CMA(No.2024CPML-C027).
文摘The extraordinary Super Typhoon(STY)Muifa(2022)made landfall four times and had a significant impact on the coastal regions from south to north of China.Although previous studies have demonstrated the‘pumping effect'of typhoons on the enhancement of reactive nitrogen(Nr)wet deposition over the ocean,it is uncertain how Nr deposition is influenced by typhoons thatmake prolonged mechanism due tomultiple landfalls.In this study,theNr wet deposition induced by STYMuifawas investigated fromthe perspective of in-and below-cloud processes based on the Nested Air Quality Prediction Modeling System with an online tracer-tagging module.High volume of Nr wet deposition caused by Muifa migrated from south to north,passing over half of China's coastal cities.Compared to the typhoon generated vicinity,both mean values of the oxidized and reduced nitrogen wet deposition over the Typhoon affected regions were increased about 20.4 and 66.1 times after landfall even with the similar rainfall.Emissions from the four landfall areas of China contributed to the majority of Nr wet deposition with significantly enhanced proportion of in-cloud deposition.The strong pumping effect of typhoon to the Nr deposition along the coastal areas and the risk of ecosystem effects requires further researches and higher demands on the control of nitrogen emissions of National Industrial Park,which usually located in China's coastal cities.
基金jointly funded by the National Key R&D Program of China[grant numbers 2019YFC1510301 and 2018YFC1505702]the Basic Research Fund of the Chinese Academy of Meteorological Sciences[grant number 2020Z008].
文摘In recent years,the Cloud Imaging Probe(CIP)and Precipitation Imaging Probe(PIP)produced by Droplet Measurement Technologies(DMT)have been introduced by a number of meteorological research and operation centers in China.The supporting software provided by DMT,i.e.,PADS(Particle Analysis and Display System),cannot output detailed information on each individual particle,which definitely limits the in-depth utilization of cloud and precipitation particle image data in China.In this paper,particle-by-particle information was extracted by decompressing the CIP and PIP original particle image data,based on which a new definition of the dimension for nonspherical particles is proposed by using the area of the convex hull enclosing a particle to obtain the equivalent diameter of a circle with equal area.Based on the data detected during one flight in Inner Mongolia,the particle size distribution obtained using the new particle size definition and that used by the other four existing definitions are compared.The results show that the particle number concentration calculated using different particle size definitions can vary by up to an order of magnitude.The result obtained based on the new particle size definition is closest to that calculated with the area-equivalent diameter definition.
基金financially supported by the National Natural Science Foundation of China(Nos.21872102 and 22172080)the Fundamental Research Funds for the Central Universities,Nankai University(No.63231195)Tianjin“Project+Team”Innovation Team,2020。
文摘Efficient activation of molecular oxygen(O_(2))is considered a promising technique for the removal of antibiotics.However,how to effectively regulate electrons distribution to promote O_(2)activation remains a challenge at present.In this study,phosphorus and sodium co-doped carbon nitride(PNaCN)were designed to rearrange the electrons distribution to activate O_(2)for the degradation of tetracycline.The generation of·O_(2)~-was innovatively observed via in-situ O_(2)fitting Fourier transform infrared(FTIR)spectroscopy,demonstrating the outstanding O_(2)activation ability of PNa5.Density functional theory(DFT)further confirmed that the rational co-doping led to the rearrangement of local electrons,resulting in electron-rich Na sites and electron-deficient P sites.These sites exhibited greater susceptibility to O_(2)adsorption and charge transfer.Besides,the degradation rate of tetracycline was increased by 2.44 times using co-doped CN.This study provides a new inspiration for enhancing O_(2)activation by inducing electrons rearrangement.
基金supported by the National Key R&D Program of China(2019YFC1510305)the National Natural Science Foundation of China(Grant Nos.41705119 and 41575131)+2 种基金Baojun CHEN also acknowledges support from the CMA Key Innovation Team(CMA2022ZD10)Qiujuan FENG was supported by the General Project of Natural Science Research in Shanxi Province(20210302123358)the Key Projects of Shanxi Meteorological Bureau(SXKZDDW20217104).
文摘To evaluate the ability of the Predicted Particle Properties(P3)scheme in the Weather Research and Forecasting(WRF)model,we simulated a stratiform rainfall event over northern China on 22 May 2017.WRF simulations with two P3 versions,P3-nc and P3-2ice,were evaluated against rain gauge,radar,and aircraft observations.A series of sensitivity experiments were conducted with different collection efficiencies between ice and cloud droplets.The comparison of the precipitation evolution between P3-nc and P3-2ice suggested that both P3 versions overpredicted surface precipitation along the Taihang Mountains but underpredicted precipitation in the localized region on the leeward side.P3-2ice had slightly lower peak precipitation rates and smaller total precipitation amounts than P3-nc,which were closer to the observations.P3-2ice also more realistically reproduced the overall reflectivity structures than P3-nc.A comparison of ice concentrations with observations indicated that P3-nc underestimated aggregation,whereas P3-2ice produced more active aggregation from the self-collection of ice and ice-ice collisions between categories.Efficient aggregation in P3-2ice resulted in lower ice concentrations at heights between 4 and 6 km,which was closer to the observations.In this case,the total precipitation and precipitation pattern were not sensitive to riming.Riming was important in reproducing the location and strength of the embedded convective region through its impact on ice mass flux above the melting level.
基金supported by the National Key R&D Program of China(No.2024YFC3714200)Guangxi Key Research and Development Program,China(No.Guike AB24010074)+2 种基金the National Natural Science Foundation of China(Nos.22276099,U24A20515 and 22361162668)the Natural Science Foundation of Jiangsu Province(No.BK20240036)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX24_1529).
文摘Temperature has a substantial impact on the emission of biogenic volatile organic compounds(BVOCs).Moder-ate warm temperatures,e.g.,30–40°C,could boost plant metabolism,increasing BVOC emissions.Against the backdrop of global warming,plants emit more BVOCs to cope with thermal stress,leading to elevated concen-trations of tropospheric ozone(O_(3))and secondary organic aerosols(SOA).In recent years,a considerable body of research has explored the interaction between tree species and BVOCs under the influence of various environ-mental factors.Although many studies have examined explored the temperature dependence of BVOC emissions in the past,few studies have conducted a comprehensive and in-depth investigation into the impacts of tempera-ture.This review summarizes the relevant studies on BVOCs in the past decade,including the main biosynthetic pathways,emission observation techniques and emission inventories,as well as how temperature affects isoprene and monoterpene emission rates and the formation of O_(3) and SOA.Our work offers a theoretical foundation and guidance for future efforts to advance the comprehension of BVOC emission characteristics and develop strategies to mitigate secondary pollution.
基金Supported by the Key Science and Technology Project of Henan Province(252102321006 and 242102320037)Henan Key Laboratory of Agrometeorological Safeguard Application Techniques(KM202220,KQ202022,and KQ202425)+2 种基金Fengyun Application Pioneer-ing Project(20220111)Central Regional Weather Modification Capacity Building Project of China Meteorological Administration,Weather Modification Research Experiment in Danjiangkou Reservoir(ZQC-H22255)Research Experiment on Rain&Snow Enhancement Through Cloud Seeding in Stratiform Clouds with Embedded Convection in Central China(Shangqiu)(ZQC-H22256)。
文摘Previous satellite observations have identified the appearance of“cloud trough”(or“cloud trench”),with cloud tops visually collapsed following airborne cloud seeding operation,demonstrating the effect of weather modification.However,refined observations of troughed clouds and associated microphysical processes are still notably scarce,especially those obtained via in-situ aircraft measurements.In this study,variations in cloud microphysics associated with and without troughed clouds along an airborne stratiform cloud seeding path over central China on 15 December 2019 are analyzed and compared based on aircraft measurements,ground-based radar observations,and FY-4A satellite imagery.The results are as follows.(1)The troughed clouds were mainly formed to the northeast of the flight path and were observed only in some parts of the seeded stratiform clouds.The seeding tracks became visible starting from 60 min after seeding and persisted for approximately 3 h,covering a maximum width of 30–40 km in FY-4A imagery.Radar echo enhancements can be observed by a ground-based radar at some parts of the seeding tracks.(2)The troughed clouds were observed only when the ambient air temperature(T)was≤-7℃,a condition favoring high nucleation efficiency of silver iodide(Ag I)aerosols,whereas no cloud troughs formed at higher temperatures.(3)The troughed clouds with strong radar echoes(i.e.,large precipitation)corresponded to regions with high values(>0.1 g m^(-3))of supercooled water content after cloud seeding,which facilitated the growth of precipitation particles.(4)Within the troughed clouds,the cloud optical thickness and cloud top height decreased,while the effective radii of cloud particles increased by nearly 10μm.These results provide valuable guidance for optimizing cold cloud seeding conditions in artificial rainfall enhancement.Meanwhile,the presence of high supercooled water content,particularly the threshold of supercooled water content,is a critical factor for strong precipitation,which necessitates further studies.
基金Supported by the Beijing Natural Science Foundation(8242029)Beijing Municipal Science and Technology Commission(Z221100005222016)+1 种基金Science&Technology Plan Project of Fujian Province(2021L3019)Open Grants of the State Key Laboratory of Severe Weather(2023LASW-B02)。
文摘Raindrop size distribution(DSD)is crucial in the study of precipitation microphysics,but the parameters that characterize the DSD is not easy to be derived accurately.Wind profile radar(WPR)provides rich data with high spatiotemporal resolution and low attenuation,and the previous studies using WPR power spectral distribution to extract DSD parameters demonstrate certain limitations.In this study,a WPR-based Gamma DSD parameter estimation network(WPR-DSDnet)combined with a neural network(NN)and a long short-term memory(LSTM)network is designed,and then a WPR-DSDnet-based model is trained to retrieve the Gamma DSD parameters including normalized intercept parameter(N_(w))and mass-weighted average diameter(D_(m))by means of the high-resolution WPR reflectivity factor and velocity spectral width as the inputs,and the spatiotemporal matching disdrometer data collected from 2017 to 2021 in Beijing as labels.Two precipitation cases are used to validate the performance of the model,and the results demonstrate that the model can retrieve the Gamma DSD parameters effectively,in which the ratio between the estimated and measured values of both lg N_(w)and D_(m)exceeds 99%.The estimation accuracy of lg N_(w)is slightly better than that of D_(m)due to smaller relative deviation of lg N_(w)although the absolute deviation between the estimated and true values of lg N_(w)is larger than that of D_(m),which are probably caused by the larger distribution range of lg N_(w).The vertical distributions of lg N_(w)closely aligns with variations in precipitation intensity,which hints it is a useful indicator for precipitation intensity change.On the other hand,the distribution of D_(m)is closely associated with the degree of convection,which is valuable for precipitation recognition and classification.The two parameters extracted by the deep learning-based model can facilitate further in-depth analysis on precipitation characteristics and mechanisms with WPR data.
基金Supported by the National Natural Science Foundation of China(42205044)National Key Research and Development Program of China(2024YFF1308202)+2 种基金Fengyun Application Pioneer Project(FY-APP-2022.0111)Project for the Capacity Construction of Weather Modification in Southwest China[SCIT-ZG(Z)-2024100001]Wuxi University Research Start-up Fund for Introduced Talents(2024r045)。
文摘Cloud water plays an important role in the global atmospheric water cycle and weather modification,but cloud is one of the most uncertain parameters in the study of weather and climate.The cloud water products from different data sources may have considerable discrepancies.In this study,the total cloud liquid water(termed as cloud liquid water path,LWP)obtained from satellite observations[Advanced Himawari Imager(AHI)and Advanced Microwave Scanning Radiometer(AMSR)]and three sets of modern reanalysis data(ERA5,JRA-55,and MERRA-2)are compared and analyzed.Moreover,characteristics of vertical distributions of cloud liquid water content(LWC)in different regions over East Asia are analyzed by using the profile data from the reanalyses.The main findings are as follows:(1)in extensive warm marine clouds,AHI and AMSR have a good agreement(with the correlation coefficient larger than 0.7)but with an overestimation from AHI;(2)under warm cloud conditions,the LWP in ERA5shows a significant positive bias(about 0.065 kg m^(-2))over land,while MERRA-2 is closer to the satellite product compared with ERA5 and JRA-55;and(3)Southwest China(SW)is the area with most abundant LWC.The LWC is mainly concentrated in the middle and lower troposphere in the study area,and the LWC in ERA5 is higher than that in MERRA-2 and JRA-55.Overall,satellite observations and reanalyses exhibit significant inconsistency for cloud LWP,which needs further investigation and understanding.
基金Supported by the National Natural Science Foundation of China(42122038 and 42230604)。
文摘Cloud effective radius(CER)is a fundamental microphysical property of clouds,critical for understanding cloud formation and radiative effects.Satellite spectral imagers,widely utilized in passive remote sensing,facilitate the monitoring of cloud characteristics,including CER,over extended time periods and spatial scales.Various observational methods have been employed to evaluate satellite cloud property products;however,in situ measurement evaluations of CER remain limited,particularly for products over China.This study utilized aircraft observations provided by the China Meteorological Administration Weather Modification Centre to evaluate the CER retrieved by Fengyun-4A Advanced Geosynchronous Radiation Imager(AGRI)and Himawari-8 Advanced Himawari Imager(AHI).Three flights were selected from the aircraft dataset for evaluation,involving flights through non-precipitating stratiform clouds with stable,high-quality measurements.Rigorous data selection and collocation procedures were employed to ensure a comprehensive comparison.Satellite retrievals from heterogeneous cloud fields were excluded,and representative in-cloud aircraft measurements were identified through multi-parameter filtering.The flight trajectory was adjusted to account for horizontal cloud movement corresponding to time differences between observations from different platforms.Additionally,in situ measurements from different vertical layers were adjusted to a comparable position near the cloud top.Results indicate that CER retrieved from satellites is generally overestimated compared to in situ measurements.For AGRI,the average difference(AD)is 2.90μm,with a root mean square difference(RMSD)of 3.53μm.For AHI,the AD is 2.92μm,and the RMSD is 3.59μm.To enhance future validation and evaluation of remote sensing results,factors such as instrument calibration,flight patterns,and cloud conditions will be carefully considered.Increasing the number of cases should further reduce errors associated with individual instances,enabling more precise assessments.
基金Supported by the National Key Research and Development Program of China (2019YFC1510301)Key Innovation Team Fund of the China Meteorological Administration (CMA2022ZD10)Basic Research Fund of the Chinese Academy of Meteorological Sciences(2021Y010)。
文摘The airborne two-dimensional stereo(2D-S) optical array probe has been operating for more than 10 yr, accumulating a large amount of cloud particle image data. However, due to the lack of reliable and unbiased classification tools,our ability to extract meaningful morphological information related to cloud microphysical processes is limited. To solve this issue, we propose a novel classification algorithm for 2D-S cloud particle images based on a convolutional neural network(CNN), named CNN-2DS. A 2D-S cloud particle shape dataset was established by using the 2D-S cloud particle images observed from 13 aircraft detection flights in 6 regions of China(Northeast, Northwest, North,East, Central, and South China). This dataset contains 33,300 cloud particle images with 8 types of cloud particle shape(linear, sphere, dendrite, aggregate, graupel, plate, donut, and irregular). The CNN-2DS model was trained and tested based on the established 2D-S dataset. Experimental results show that the CNN-2DS model can accurately identify cloud particles with an average classification accuracy of 97%. Compared with other common classification models [e.g., Vision Transformer(ViT) and Residual Neural Network(ResNet)], the CNN-2DS model is lightweight(few parameters) and fast in calculations, and has the highest classification accuracy. In a word, the proposed CNN-2DS model is effective and reliable for the classification of cloud particles detected by the 2D-S probe.
基金Supported by the National Natural Science Foundation of China(41775139)Ministry of Science and Technology of China(2016YFE0201900 and GYHY201406033)China Meteorological Administration(ZQC-R18169/RYSY201904).
文摘Understanding the characteristics of cloud water resource(CWR)and precipitation efficiency of hydrometeors(PEh)is imperative for the application of CWR in Northwest China.The atmospheric precipitable water(PW)in all four seasons and clouds and PEh in summer were studied with ERA-5 and CloudSat data in this region.The results show that topography,especially in the Tibetan Plateau,exerts significant impacts on the precipitation and PW in summer,since large amounts of clouds are distributed along the mountain ranges.The study region is divided into four typical areas:the monsoon area in eastern Northwest China(NWE),the Qilian Mountains area(QM),the Tianshan Mountains area(TM),and the Source of Three Rivers area(STR).Over the four areas,cloud top height(6.3 km)and cloud base height(3.3 km)over NWE are higher,and precipitating clouds are thicker(7 km)in the single-layer clouds.Liquid water content decreases with increasing altitude,while the ice water content first increases and then decreases.Liquid water path is higher over NWE(0.11 kg m^(−2))than over TM and STR(0.05 kg m^(−2)),and the ice water path is mainly concentrated within the range of 0.025–0.055 kg m^(−2).The PEh values are distributed unevenly and affected evidently by the terrain.Although the PEh values in the four typical areas(0.3–0.6)are higher than those in other regions,the CWR is relatively abundant and has a higher exploitation potential.Therefore,it is well-founded to exploit CWR for alleviating water shortages in these areas of Northwest China in summer.
基金Supported by the National Key Research and Development Program of China (2016YFE0201900-02 and 2019YFC1510304)National Natural Science Foundation of China (41575037)。
文摘This study investigated the cloud microphysical processes and atmospheric water budget during the extreme precipitation event on 20 July 2021 in Zhengzhou of Henan Province,China,based on observations,reanalysis data,and the results from the high-resolution large-eddy simulation nested in the Weather Research and Forecasting(WRF)model with assimilation of satellite and radar observations.The results show that the abundant and persistent southeasterly supply of water vapor,induced by Typhoons In-Fa and Cempaka,under a particular synoptic pattern featured with abnormal northwestward displacement of the western Pacific subtropical high,was conducive to warm rain processes through a high vapor condensation rate of cloud water and an efficient collision–coalescence process of cloud water to rainwater.Such conditions were favorable for the formation and maintenance of the quasi-stationary warmsector heavy rainfall.Precipitation formation through the collision–coalescence process of cloud water to rainwater accounted for approximately 70%of the total,while the melting of snow and graupel accounted for only approximately 30%,indicating that warm cloud processes played a dominant role in this extreme rainfall event.However,enhancement of cold cloud processes promoted by latent heat release also exerted positive effect on rainfall during the period of most intense hourly rainfall.It was also found that rainwater advection from outside of Zhengzhou City played an important role in maintaining the extreme precipitation event.
基金Supported by the National Key Research and Development Program of China (2016YFA0601701)China Meteorological Administration Innovation and Development Project (CXFZ2021J039)Fengyun Satellite Application Pioneer Project (FY-APP-2021.0102)。
文摘To explore the key technologies of artificial weather modification for specific targets(e.g.,a stadium)and improve the efficiency of artificial rainfall modification for major events,this study conducts an artificial rainfall reduction experiment for the closing ceremony of Nanjing Youth Olympic Games on 28 August 2014.Satellite retrievals,radar observations,sounding data,and other sources of information as well as Cloud and Precipitation Accurate Analysis System(CPAS)are used in this study.The main conclusions are as follows.(1)On 28 August 2014,a large-scale cumulus cloud system with mixed-phase stratocumulus and stratus precipitation was observed.This system was influenced by the weak shear of a low-level trough and the precipitation was dominated by cold clouds with dry layers between clouds.Thereby,we adopted the crystal-priming over-catalytic hypothesis and conducted a rocket-catalytic rain abatement operation at a certain distance(100–25 km)from the stadium.Rocket shootings of different intensities were implemented for two echoes that affected the stadium successively(two rounds of 15 rocket shootings within15 min for an isolated weak echo IA;multiple rounds of 156 rocket shootings within 80 min for a strong echo IB).Amazingly,after the shootings with the catalysis in the air,reflectivity of the two echoes was reduced at all altitudes with the most significant reduction at the 2-km altitude,and the time needed for the obvious reduction was 40 min.The most obvious reduction of the two echoes then maintained for 60 and 53 min,respectively,and the operation time needed for the echo zone to recover after the stop of rocket shooting was 108 min for echo IA and 90 min for echo IB.The two echoes moving across the stadium during the time period of the closing ceremony(2000–2130 local time)were at their minimal strengths,with almost no echo over the target stadium.This demonstrates that the rocket shooting strategy of over-crystallization catalysis is effective,and the shooting site,time,and dose are reasonable.The following technical parameters were used during this experiment.At about 80–25 km away from the target stadium in the west,the rocket shooting lasted for 15–80 min and the doses were not less than 1 shot min~(-1)(1 shot min~(-1)for echo IA,2.25 shots min~(-1)for echo IB).The attenuation rate was 0.21 dBZ min~(-1)for the average 15 dBZ of echo IA.For the average 25 dBZ of echo IB,the attenuation rate was 0.27 dBZ min~(-1).The above technical settings helped achieve the goal of reducing rain over the stadium to almost zero for nearly 1-h period during the critical time of the event.
基金Supported by the Scientific Research Project of the Bayingol Mongolian Autonomous Prefecture in Xinjiang(202318)China Meteorological Administration(CMA)Weather Modification Centre Innovation Team Project(WMC2023IT01)CMA Key Innovation Team Project(CMA2022ZD10).
文摘In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding catalysts.Our objective was to elucidate the mechanism of snowfall enhancement in stratiform clouds in the Bayanbulak test area of Xinjiang,China.The results indicated that the optimal seeding time was the early stages of weather system development.In this case,the optimal seeding zone was identified as the northwest of the test area,especially near the cloud top(altitudes between 3500 and 4000 m,temperatures range−11 to−15℃),and the ideal concentration of catalyst was with ice crystal density of 1.0×10^(7)kg^(−1)within the target area.Under such conditions,the total precipitation rate in the seeding-affected area increased to 50.1 mm h^(−1).The results also showed that the favorable seeding region was featured by high content of supercooled water and low population of natural ice crystals,where artificial ice crystals could substantially increase the snowfall.This augmentation typically appeared in a unimodal pattern,with the peak formed within 2–3 h after seeding.Seeding in the ice–water mixed zone of a supercooled cloud facilitated rapid ice crystal growth to snow-flake pieces via the Bergeron process,which in turn consumed more supercooled water via collision–coalescence with cloud water droplets.Simultaneously,the intensive consumption of supercooled water impeded the riming process and reduced the formation of graupel particles within the cloud.The dispersion of artificial ice crystals extended over tens of kilometers horizontally;however,in the vertical direction most particles remained approximately 1 km below the seeding layer,due to limited vertical ascent rate in the stratiform clouds restricting upward movement of artificial ice crystals.The above results help better understand the snowfall enhancement mechanism in stratiform clouds and facilitate related weather modification practice.
