Heavy precipitation and extreme drought have caused severe economic losses over South China and Indochina(INCSC)in recent decades.Given the areas with large gross domestic product(GDP)in the INCSC region are distribut...Heavy precipitation and extreme drought have caused severe economic losses over South China and Indochina(INCSC)in recent decades.Given the areas with large gross domestic product(GDP)in the INCSC region are distributed along the coastline and greatly affected by global warming,understanding the possible economic impacts induced by future changes in the maximum consecutive 5-day precipitation(RX5day)and the maximum consecutive dry days(CDD)is critical for adaptation planning in this region.Based on the latest data released by phase 6 of the Coupled Model Intercomparison Project(CMIP6),future projections of precipitation extremes with bias correction and their impacts on GDP over the INCSC region under the fossil-fueled development Shared Socioeconomic Pathway(SSP5-8.5)are investigated.Results indicate that RX5day will intensify robustly throughout the INCSC region,while CDD will lengthen in most regions under global warming.The changes in climate consistently dominate the effect on GDP over the INCSC region,rather than the change of GDP.If only considering the effect of climate change on GDP,the changes in precipitation extremes bring a larger impact on the economy in the future to the provinces of Hunan,Jiangxi,Fujian,Guangdong,and Hainan in South China,as well as the Malay Peninsula and southern Cambodia in Indochina.Thus,timely regional adaptation strategies are urgent for these regions.Moreover,from the sub-regional average viewpoint,over two thirds of CMIP6 models agree that maintaining a lower global warming level will reduce the economic impacts from heavy precipitation over the INCSC region.展开更多
This study examines the spatio-temporal characteristics of heavy precipitation forecasts in eastern China from the European Centre for Medium-Range Weather Forecasts(ECMWF) using the time-domain version of the Method ...This study examines the spatio-temporal characteristics of heavy precipitation forecasts in eastern China from the European Centre for Medium-Range Weather Forecasts(ECMWF) using the time-domain version of the Method for Object-based Diagnostic Evaluation(MODE-TD). A total of 23 heavy rainfall cases occurring between 2018 and 2021 are selected for analysis. Using Typhoon “Rumbia” as a case study, the paper illustrates how the MODE-TD method assesses the overall simulation capability of models for the life history of precipitation systems. The results of multiple tests with different parameter configurations reveal that the model underestimates the number of objects’ forecasted precipitation tracks, particularly at smaller radii. Additionally, the analysis based on centroid offset and area ratio tests for different classified precipitation objects indicates that the model performs better in predicting large-area, fast-moving, and longlifespan precipitation objects. Conversely, it tends to have less accurate predictions for small-area, slow-moving, and shortlifespan precipitation objects. In terms of temporal characteristics, the model overestimates the forecasted movement speed for precipitation objects with small-area, slow movement, or both long and short lifespans while underestimating it for precipitation with fast movement. In terms of temporal characteristics, the model tends to overestimate the forecasted movement speed for precipitation objects with small-area, slow movement, or both long and short lifespans while underestimating it for precipitation with fast movement. Overall, the model provides more accurate predictions for the duration and dissipation of precipitation objects with large-area or long-lifespan(such as typhoon precipitation) while having large prediction errors for precipitation objects with small-area or short-lifespan. Furthermore, the model’s simulation results regarding the generation of precipitation objects show that it performs relatively well in simulating the generation of large-area and fast-moving precipitation objects. However, there are significant differences in the forecasted generation of small-area and slow-moving precipitation objects after 9 hours.展开更多
This study delves into the multiple weather systems and their interaction mechanisms that caused the severe rainfall event in Northeast China in early August 2023. The analysis reveals that the atmospheric circulation...This study delves into the multiple weather systems and their interaction mechanisms that caused the severe rainfall event in Northeast China in early August 2023. The analysis reveals that the atmospheric circulation in the mid-to-high latitudes of the Eurasian continent exhibited a significant “two troughs and two ridges” structure, with Northeast China located precisely in the peripheral region of the subtropical high, significantly influenced by its marginal airflows. Additionally, the residual circulation of Typhoon “Doksuri” interacting with the subtropical high and upper-level troughs significantly increased the rainfall intensity and duration in the region. In particular, the continuous and powerful transport of the southwest jet provided the necessary moisture and unstable conditions for the generation and development of convective systems. The rainfall event resulted in nearly 40,000 people affected and crop damage covering an area of approximately 4000 hectares, demonstrating the severity of extreme weather. The study emphasizes that strengthening meteorological monitoring and early warning systems, as well as formulating and improving emergency response mechanisms, are crucial for reducing potential disaster losses caused by heavy rainfall. Future research can further explore the interaction mechanisms among weather systems, limitations of data sources, and the connection between long-term trends of heavy rainfall events and global climate change.展开更多
A record-breaking heavy rainfall event that occurred in Zhengzhou,Henan province during 19–21 July 2021 is simulated using the Weather Research and Forecasting Model,and the large-scale precipitation efficiency(LSPE)...A record-breaking heavy rainfall event that occurred in Zhengzhou,Henan province during 19–21 July 2021 is simulated using the Weather Research and Forecasting Model,and the large-scale precipitation efficiency(LSPE)and cloud-microphysical precipitation efficiency(CMPE)of the rainfall are analyzed based on the model results.Then,the key physical factors that influenced LSPE and CMPE,and the possible mechanisms for the extreme rainfall over Zhengzhou are explored.Results show that water vapor flux convergence was the key factor that influenced LSPE.Water vapor was transported by the southeasterly winds between Typhoon In-Fa(2021)and the subtropical high,and the southerly flow of Typhoon Cempaka(2021),and converged in Zhengzhou due to the blocking by the Taihang and Funiu Mountains in western Henan province.Strong moisture convergence centers were formed on the windward slope of the mountains,which led to high LSPE in Zhengzhou.From the perspective of CMPE,the net consumption of water vapor by microphysical processes was the key factor that influenced CMPE.Quantitative budget analysis suggests that water vapor was mainly converted to cloud water and ice-phase particles and then transformed to raindrops through melting of graupel and accretion of cloud water by rainwater during the heavy precipitation stage.The dry intrusion in the middle and upper levels over Zhengzhou made the high potential vorticity descend from the upper troposphere and enhanced the convective instability.Moreover,the intrusion of cold and dry air resulted in the supersaturation and condensation of water vapor,which contributed to the heavy rainfall in Zhengzhou.展开更多
The northeastern China cold vortex(NCCV)plays an important role in regional rainstorms over East Asia.Using the National Centers for Environmental Prediction Final reanalysis dataset and the Global Precipitation Measu...The northeastern China cold vortex(NCCV)plays an important role in regional rainstorms over East Asia.Using the National Centers for Environmental Prediction Final reanalysis dataset and the Global Precipitation Measurement product,an objective algorithm for identifying heavy-precipitation NCCV(HPCV)events was designed,and the climatological features of 164 HPCV events from 2001 to 2019 were investigated.The number of HPCV events showed an upward linear trend,with the highest frequency of occurrence in summer.The most active region of HPCV samples was the Northeast China Plain between 40°–55°N.Most HPCV events lasted 3–5 days and had radii ranging from 250 to 1000 km.The duration of HPCV events with larger sizes was longer.About half of the HPCV events moved into(moved out of)the definition region(35°–60°N,115°–145°E),and half initiated(dissipated)within the region.The initial position was close to the western boundary of the definition region,and the final position was mainly near the eastern boundary.The locations associated with the precipitation were mostly concentrated within 2000 km southeast of the HPCV systems,and they were farther from the center in the cold season than in the warm season.展开更多
In order to better understand the formation mechanism of rainstorm in China and promote disaster prevention and reduction, based on the meteorological data of National Meteorological Information Center and Japan Meteo...In order to better understand the formation mechanism of rainstorm in China and promote disaster prevention and reduction, based on the meteorological data of National Meteorological Information Center and Japan Meteorological Agency, this paper draws the isobaric surface map of 850 hPa and 500 hPa, relative humidity and precipitation distribution map. In this study, synoptic methods were used to analyze the heavy precipitation process in North China from August 23th to 24th, 2020. The results show that 1) The formation of short-term heavy precipitation requires sufficient water vapor and very strong upward movement;2) the heavy precipitation in August 23th to 24th 2020 in North China was influenced by the upper-level trough line, cold vortex and cold front, which made the warm and cold air strongly converge over North China, resulting in strong convective weather;3) the heavy rainfall over North China was also influenced by Typhoon Bawei, which caused maximum precipitation and air humidity.展开更多
Based on 740 stations of daily precipitation datasets in China, the precipitationconcentration degree (PCD) and precipitation-concentration period (PCP) of different intensity durative precipitation events were ca...Based on 740 stations of daily precipitation datasets in China, the precipitationconcentration degree (PCD) and precipitation-concentration period (PCP) of different intensity durative precipitation events were calculated to analyze their statistical characteristics, mainly including spatial and temporal distributions, variations and climatic trends of the two parameters of the durative heavy precipitation events in China. It is proved that these two parameters of heavy rainfall can display the temporal inhomogeneity in the precipitation field. And it is also found that there is a good positive relationship between the precipitation-concentration degree and annual rainfall amount in the Eastern and Central China. This method can be anolied in flood assessment and climate change fields.展开更多
A regional heavy precipitation event that occurred over Sichuan Province on 8-9 September 2015 is analyzed based on hourly observed precipitation data obtained from weather stations and NCEP FNL data. Two moist dynami...A regional heavy precipitation event that occurred over Sichuan Province on 8-9 September 2015 is analyzed based on hourly observed precipitation data obtained from weather stations and NCEP FNL data. Two moist dynamic parameters, i.e., moist vorticity (mζ and moist divergence (mδ), are used to diagnose this heavy precipitation event. Results show that the topography over southwestern China has a significant impact on the ability of these two parameters to diagnose precipitation. When the impact of topography is weak (i.e., low altitude), rn( cannot exactly depict the location of precipitation in the initial stage of the event. Then, as the precipitation develops, its ability to depict the location improves significantly. In particular, m( coincides best with the location of precipitation during the peak stage of the event. Besides, the evolution of the m( center shows high consistency with the evolution of the precipitation center. For mδ, although some false-alarm regions are apparent, it reflects the location of precipitation almost entirely during the precipitation event. However, the mδ center shows inconsistency with the precipitation center. These results suggest that both m( and mδ have a significant ability to predict the location of precipitation. Moreover, m( has a stronger ability than mδ in terms of predicting the variability of the precipitation center. However, when the impact of topography is strong (i.e., high altitude), both of these two moist dynamic parameters are unable to depict the location and center of precipitation during the entire precipitation event, suggesting their weak ability to predict precipitation over complex topography.展开更多
In earlier studies,objective techniques have been used to determine the contribution of tropical cyclones to precipitation(TCP)in a region,where the Tropical cyclone Precipitation Event(TPE)and the Regional Heavy Prec...In earlier studies,objective techniques have been used to determine the contribution of tropical cyclones to precipitation(TCP)in a region,where the Tropical cyclone Precipitation Event(TPE)and the Regional Heavy Precipitation Events(RHPEs)are defined and investigated.In this study,TPE and RHPEs are combined to determine the Typhoon Regional Heavy Precipitation Events(TRHPEs),which is employed to evaluate the contribution of tropical cyclones to regional extreme precipitation events.Based on the Objective Identification Technique for Regional Extreme Events(OITREE)and the Objective Synoptic Analysis Technique(OSAT)to define TPE,temporal and spatial overlap indices are developed to identify the combined events as TRHPE.With daily precipitation data and TC best-track data over the western North Pacific from 1960 to 2018,86 TRHPEs have been identified.TRHPEs contribute as much as 20%of the RHPEs,but100%of events with extreme individual precipitation intensities.The major TRHPEs continued for approximately a week after tropical cyclone landfall,indicating a role of post landfall precipitation.The frequency and extreme intensity of TRHPEs display increasing trends,consistent with an observed positive trend in the mean intensity of TPEs as measured by the number of daily station precipitation observations exceeding 100 mm and 250 mm.More frequent landfalling Southeast and South China TCs induced more serious impacts in coastal areas in the Southeast and the South during 1990-2018 than1960-89.The roles of cyclone translation speed and"shifts"in cyclone tracks are examined as possible explanations for the temporal trends.展开更多
[Objective] The aim was to analyze one strong precipitation process in Northern Guangxi from May 27 to 28 in 2010.[Method] By dint of 2.5×2.5 NCEP reanalysis data,physical quantities such as the water vapor flux,...[Objective] The aim was to analyze one strong precipitation process in Northern Guangxi from May 27 to 28 in 2010.[Method] By dint of 2.5×2.5 NCEP reanalysis data,physical quantities such as the water vapor flux,pseudo-equivalent temperature,Non-geotropic wet Q vector in one front rainstorm process in north Guangxi from May 27 to 28 in 2010 was expounded.The forecast application of Non-geotropic wet Q vector in rainstorm falling area in Guangxi during early flood period was discussed.[Result] The water vapor in Bay of Bengal transported to Guangxi and formed convergence lifting movement in north Guangxi,which provided favorable water vapor transportation condition for the generation of strong precipitation in north Guangxi.The 850 hPa pseudo-equivalent temperature front (close area) moved southward to the north part of Guangxi.North Guangxi was in pseudo-equivalent temperature area.The highly wet unstable energy of lower layer and the cold air penetrating downward from the middle layer led to potential instability in the lower level established in northern Guangxi,which thus provided certain thermal condition for the strong precipitation process;Northern Guangxi was in the overlap region of the maximum gradient region of contour Qx at 850 hPa and stronger negative areas of ▽Q,which provided favorable dynamic condition for the rainstorm process in northern Guangxi in the future.[Conclusion] The study provided reference in accordance to the forecast of rainstorm.展开更多
Soil washing, ex situ mechanical technique, is one of the few permanent treatment alternatives to remove metal contaminants from soils by employing physical separation based on mineral processing technologies to remov...Soil washing, ex situ mechanical technique, is one of the few permanent treatment alternatives to remove metal contaminants from soils by employing physical separation based on mineral processing technologies to remove discrete particles or metal-bearing particles and/or chemical extraction based on leaching or dissolving process to extract the metals from the soils into an aqueous solution. However, washwater remained from soil washing process contains discrete particulate particles along with heavy metals as solution phase to be treated separately, as well as this process can produce large amount of sludge that requires further treatment, slow metal precipitation, poor settling, the aggregation of metal precipitates. Electrical treatments including electrocoagulation and electrolysis can be effective in removing these substances from washwater. This paper reviews the theoretical models in applying electrocoagulation and electrolysis to remove heavy metals and discrete particulate particles in washwater by examining and comparing the status of washwater treatment technologies which have been undertaken, mostly in the US and EU for the period 1990-2012.展开更多
This paper comprehensively studies the spatio-temporal characteristics of the frequency of extremely heavy precipitation events over South China by using the daily precipitation data of 110 stations during 1961 to 200...This paper comprehensively studies the spatio-temporal characteristics of the frequency of extremely heavy precipitation events over South China by using the daily precipitation data of 110 stations during 1961 to 2008 and the extremely heavy precipitation thresholds determined for different stations by REOF, trend coefficients, linear trend, Mann-Kendall test and variance analysis. The results are shown as follows. The frequency distribution of extremely heavy precipitation is high in the middle of South China and low in the Guangdong coast and western Guangxi. There are three spatial distribution types of extremely heavy precipitation in South China. The consistent anomaly distribution is the main type. Distribution reversed between the east and the west and between the south and the north is also an important type. Extremely heavy precipitation events in South China mainly occurred in the summer-half of the year. Their frequency during this time accounts for 83.7% of the total frequency. In the 1960 s and 1980 s, extremely heavy precipitation events were less frequent while having an increasing trend from the late 1980 s. Their climatological tendency rates decrease in the central and rise in the other areas of South China, and on average the mean series also shows an upward but insignificant trend at all of the stations. South China's frequency of extremely heavy precipitation events can be divided into six major areas and each of them shows a different inter-annual trend and three of the representative stations experience abrupt changes by showing remarkable increases in terms of Mann-Kendall tests.展开更多
Based on the observation data from the automatic rainfall station and NCEP/NCAR reanalysis data,circulation analysis and diagnosis analysis of potential vorticity in a heavy rainfall process in September 2017 in Qujin...Based on the observation data from the automatic rainfall station and NCEP/NCAR reanalysis data,circulation analysis and diagnosis analysis of potential vorticity in a heavy rainfall process in September 2017 in Qujing were conducted.The results show that the heavy rainfall was mainly affected by the convergence zone between the two high pressures and shear line system,the precipitation area developed from the west to the southeast of Qujing,and the heavy rainfall area was concentrated in the central area.The southerly airflow in the middle and lower layers of the troposphere provided favorable water vapor conditions for heavy precipitation.The precipitation was characterized by high intensity,strong suddenness and small time scale.The heavy precipitation was concentrated from 04:00 to 06:00 on September 6.The high-and low-value centers of dry potential vorticity PV at 500 h Pa were indicative of the activities of cold and warm air in the process of heavy rainfall,and representative of the development of the convergence zone and the activities of shear line.That is to say,the high-value zone of dry potential vorticity PV at 500 h Pa was strengthened to penetrate into the center of Yunnan,leading the northerly airflow to the convergence zone.The deep southerly airflow in the relatively low-value zone of PV was uplifted to the north,converging the cold and warm air at the front of the convergence zone,resulting in heavy precipitation in Qujing.The high-value zone of wet potential vorticity MPV at 700 h Pa can also indicate the characteristics of unstable warm and humid air flow activity.MPV1<0,and MPV2>0,which easily caused the unstable energy release of wet convection and formed heavy precipitation.展开更多
Convective/large-scale(C/L)precipitation partitions are crucial for achieving realistic rainfall modeling and are classified in 16 phase 6 of the Coupled Model Intercomparison Project(CMIP6)atmospheric models.Only 4 m...Convective/large-scale(C/L)precipitation partitions are crucial for achieving realistic rainfall modeling and are classified in 16 phase 6 of the Coupled Model Intercomparison Project(CMIP6)atmospheric models.Only 4 models capture the feature that convective rainfall significantly exceeds the large-scale rainfall component in the tropics while the other 12 models show 50%–100%large-scale rainfall component in heavy rainfall.Increased horizontal resolution generally increases the convective rainfall percentage,but not in all models.The former 4 models can realistically reproduce two peaks of moisture vertical distribution,respectively located in the upper and the lower troposphere.In contrast,the latter 12 models correspond to three types of moisture vertical profile biases:(1)whole mid-to-lower tropospheric wet biases(60%–80%large-scale rainfall);(2)mid-tropospheric wet peak(50%convective/large-scale rainfall);and(3)lower-tropospheric wet peak(90%–100%large-scale rainfall).And the associated vertical distribution of unique clouds potentially causes different climate feedback,suggesting accurate C/L rainfall components are necessary to reliable climate projection.展开更多
[ Objective] The study aimed to discuss analyze climate change characteristics and return periods of heavy precipitation in the northeast side of Qinghai-Tibet Plateau. [ Method] Based on the data of daily precipitati...[ Objective] The study aimed to discuss analyze climate change characteristics and return periods of heavy precipitation in the northeast side of Qinghai-Tibet Plateau. [ Method] Based on the data of daily precipitation from 1943 to 2008 in 6 representative meteorological stations in Linxia located in the northeast side of Qinghai-Tibet Plateau, the climate change characteristics of heavy precipitation were analyzed, and the return periods of heavy precipitation were calculated by Pearson-Ill probability distribution method. [ Result] Days of heavy precipitation in Linxia region in- creased conspicuously since the 1990s. The return periods of heavy precipitation in the six stations on August 20, 2008 were consistent with the re- sults of artificial estimation. [ Conclusion] The research could provide scientific references for the reasonable utilization of climate resources, disas- ter prevention and rational arranqement of anricultural plantina svstems in Linxia reaion.展开更多
Based on the conventional observation data,dual polarization radar data and NCEP reanalysis data,the large-scale circulation background field,mesoscale conditions and formation causes of a heavy rainstorm in Nanchang ...Based on the conventional observation data,dual polarization radar data and NCEP reanalysis data,the large-scale circulation background field,mesoscale conditions and formation causes of a heavy rainstorm in Nanchang on July 7,2020 were studied.It was found that this heavy rainstorm occurred under the weather background of the confrontation between the northward air flow behind the trough and the strong southwest warm and humid air flow to the northwest of the subtropical high.The divergence at the upper level,the shear in the middle and low levels,the southward movement of cold air at the low level,unusually abundant water vapor and high unstable energy caused the heavy rainstorm weather.In this process,under the influence of continuous eastward movement of several strong echo cells,an obvious"train effect"was formed in Nanchang,so that the local rainfall was continuous and intense.Moreover,the average of VIL was about 17 kg/m 2,and its variation characteristics were consistent with the variation trend of 5-min rainfall intensity,which had a certain indicator effect on short-term heavy precipitation.The topography of the Meiling Mountain in the west of Nanchang had a great influence on the formation and precipitation distribution of the heavy rain process.There was a strong rainstorm center near the mountain,and the precipitation was obviously larger than that in the plain area.展开更多
In this study,the Dynamical-Statistical-Analog Ensemble Forecast model(DSAEF_LTP model)for landfalling tropical cyclone(LTC)precipitation was employed to simulate the precipitation of 10 LTCs that occurred over China ...In this study,the Dynamical-Statistical-Analog Ensemble Forecast model(DSAEF_LTP model)for landfalling tropical cyclone(LTC)precipitation was employed to simulate the precipitation of 10 LTCs that occurred over China in 2018.With similarity region scheme(SRS)parameter values added and TC intensity introduced to the generalized initial value(GIV),four groups of precipitation simulation experiments were designed to verify the forecasting ability of the improved model for more TC samples.Results show that the simulation ability of the DSAEF_LTP model can be optimized regardless of whether adding SRS values only,or introducing TC intensity into GIV,while the experiment with both the two improvements shows a more prominent advantage in simulating the heavier precipitation of LTCs.Compared with four NWP models(i.e.,ECMWF,GFS,GRAPES and SMS-WARMS),the overall forecasting performance of the DSAEF_LTP model achieves a better result in simulating precipitation at the thresholds over 250 mm and performs slightly better than NWP models at the thresholds over 100 mm.展开更多
文摘Heavy precipitation and extreme drought have caused severe economic losses over South China and Indochina(INCSC)in recent decades.Given the areas with large gross domestic product(GDP)in the INCSC region are distributed along the coastline and greatly affected by global warming,understanding the possible economic impacts induced by future changes in the maximum consecutive 5-day precipitation(RX5day)and the maximum consecutive dry days(CDD)is critical for adaptation planning in this region.Based on the latest data released by phase 6 of the Coupled Model Intercomparison Project(CMIP6),future projections of precipitation extremes with bias correction and their impacts on GDP over the INCSC region under the fossil-fueled development Shared Socioeconomic Pathway(SSP5-8.5)are investigated.Results indicate that RX5day will intensify robustly throughout the INCSC region,while CDD will lengthen in most regions under global warming.The changes in climate consistently dominate the effect on GDP over the INCSC region,rather than the change of GDP.If only considering the effect of climate change on GDP,the changes in precipitation extremes bring a larger impact on the economy in the future to the provinces of Hunan,Jiangxi,Fujian,Guangdong,and Hainan in South China,as well as the Malay Peninsula and southern Cambodia in Indochina.Thus,timely regional adaptation strategies are urgent for these regions.Moreover,from the sub-regional average viewpoint,over two thirds of CMIP6 models agree that maintaining a lower global warming level will reduce the economic impacts from heavy precipitation over the INCSC region.
基金National Key Research and Development Program of China (2021YFC3000802)National Natural Science Foundation of China (41875059)The Open Research Program of the State Key Laboratory of Severe Weather (2021LASW-A04)。
文摘This study examines the spatio-temporal characteristics of heavy precipitation forecasts in eastern China from the European Centre for Medium-Range Weather Forecasts(ECMWF) using the time-domain version of the Method for Object-based Diagnostic Evaluation(MODE-TD). A total of 23 heavy rainfall cases occurring between 2018 and 2021 are selected for analysis. Using Typhoon “Rumbia” as a case study, the paper illustrates how the MODE-TD method assesses the overall simulation capability of models for the life history of precipitation systems. The results of multiple tests with different parameter configurations reveal that the model underestimates the number of objects’ forecasted precipitation tracks, particularly at smaller radii. Additionally, the analysis based on centroid offset and area ratio tests for different classified precipitation objects indicates that the model performs better in predicting large-area, fast-moving, and longlifespan precipitation objects. Conversely, it tends to have less accurate predictions for small-area, slow-moving, and shortlifespan precipitation objects. In terms of temporal characteristics, the model overestimates the forecasted movement speed for precipitation objects with small-area, slow movement, or both long and short lifespans while underestimating it for precipitation with fast movement. In terms of temporal characteristics, the model tends to overestimate the forecasted movement speed for precipitation objects with small-area, slow movement, or both long and short lifespans while underestimating it for precipitation with fast movement. Overall, the model provides more accurate predictions for the duration and dissipation of precipitation objects with large-area or long-lifespan(such as typhoon precipitation) while having large prediction errors for precipitation objects with small-area or short-lifespan. Furthermore, the model’s simulation results regarding the generation of precipitation objects show that it performs relatively well in simulating the generation of large-area and fast-moving precipitation objects. However, there are significant differences in the forecasted generation of small-area and slow-moving precipitation objects after 9 hours.
文摘This study delves into the multiple weather systems and their interaction mechanisms that caused the severe rainfall event in Northeast China in early August 2023. The analysis reveals that the atmospheric circulation in the mid-to-high latitudes of the Eurasian continent exhibited a significant “two troughs and two ridges” structure, with Northeast China located precisely in the peripheral region of the subtropical high, significantly influenced by its marginal airflows. Additionally, the residual circulation of Typhoon “Doksuri” interacting with the subtropical high and upper-level troughs significantly increased the rainfall intensity and duration in the region. In particular, the continuous and powerful transport of the southwest jet provided the necessary moisture and unstable conditions for the generation and development of convective systems. The rainfall event resulted in nearly 40,000 people affected and crop damage covering an area of approximately 4000 hectares, demonstrating the severity of extreme weather. The study emphasizes that strengthening meteorological monitoring and early warning systems, as well as formulating and improving emergency response mechanisms, are crucial for reducing potential disaster losses caused by heavy rainfall. Future research can further explore the interaction mechanisms among weather systems, limitations of data sources, and the connection between long-term trends of heavy rainfall events and global climate change.
基金supported by the National Key Research and Development Program of China(Grant Nos.2018YFC1506801 and 2018YFF0300102)the National Natural Science Foundation of China(NSFC)(Grant No.42105013).
文摘A record-breaking heavy rainfall event that occurred in Zhengzhou,Henan province during 19–21 July 2021 is simulated using the Weather Research and Forecasting Model,and the large-scale precipitation efficiency(LSPE)and cloud-microphysical precipitation efficiency(CMPE)of the rainfall are analyzed based on the model results.Then,the key physical factors that influenced LSPE and CMPE,and the possible mechanisms for the extreme rainfall over Zhengzhou are explored.Results show that water vapor flux convergence was the key factor that influenced LSPE.Water vapor was transported by the southeasterly winds between Typhoon In-Fa(2021)and the subtropical high,and the southerly flow of Typhoon Cempaka(2021),and converged in Zhengzhou due to the blocking by the Taihang and Funiu Mountains in western Henan province.Strong moisture convergence centers were formed on the windward slope of the mountains,which led to high LSPE in Zhengzhou.From the perspective of CMPE,the net consumption of water vapor by microphysical processes was the key factor that influenced CMPE.Quantitative budget analysis suggests that water vapor was mainly converted to cloud water and ice-phase particles and then transformed to raindrops through melting of graupel and accretion of cloud water by rainwater during the heavy precipitation stage.The dry intrusion in the middle and upper levels over Zhengzhou made the high potential vorticity descend from the upper troposphere and enhanced the convective instability.Moreover,the intrusion of cold and dry air resulted in the supersaturation and condensation of water vapor,which contributed to the heavy rainfall in Zhengzhou.
基金supported by the National Key R&D Program of China under Grant No.2018YFC1507302the National Natural Science Foundation of China under Grant No.42175006+1 种基金Jiangsu Youth Talent Promotion Project(2021-084)the Basic Research Fund of CAMS under Grant No.2020R002.
文摘The northeastern China cold vortex(NCCV)plays an important role in regional rainstorms over East Asia.Using the National Centers for Environmental Prediction Final reanalysis dataset and the Global Precipitation Measurement product,an objective algorithm for identifying heavy-precipitation NCCV(HPCV)events was designed,and the climatological features of 164 HPCV events from 2001 to 2019 were investigated.The number of HPCV events showed an upward linear trend,with the highest frequency of occurrence in summer.The most active region of HPCV samples was the Northeast China Plain between 40°–55°N.Most HPCV events lasted 3–5 days and had radii ranging from 250 to 1000 km.The duration of HPCV events with larger sizes was longer.About half of the HPCV events moved into(moved out of)the definition region(35°–60°N,115°–145°E),and half initiated(dissipated)within the region.The initial position was close to the western boundary of the definition region,and the final position was mainly near the eastern boundary.The locations associated with the precipitation were mostly concentrated within 2000 km southeast of the HPCV systems,and they were farther from the center in the cold season than in the warm season.
文摘In order to better understand the formation mechanism of rainstorm in China and promote disaster prevention and reduction, based on the meteorological data of National Meteorological Information Center and Japan Meteorological Agency, this paper draws the isobaric surface map of 850 hPa and 500 hPa, relative humidity and precipitation distribution map. In this study, synoptic methods were used to analyze the heavy precipitation process in North China from August 23th to 24th, 2020. The results show that 1) The formation of short-term heavy precipitation requires sufficient water vapor and very strong upward movement;2) the heavy precipitation in August 23th to 24th 2020 in North China was influenced by the upper-level trough line, cold vortex and cold front, which made the warm and cold air strongly converge over North China, resulting in strong convective weather;3) the heavy rainfall over North China was also influenced by Typhoon Bawei, which caused maximum precipitation and air humidity.
基金Concentrated fund item of nationalscience and technology foundation work,No.2001DEA30029-0604Jiangsunaturalsciencefoundation,No.BK2005163
文摘Based on 740 stations of daily precipitation datasets in China, the precipitationconcentration degree (PCD) and precipitation-concentration period (PCP) of different intensity durative precipitation events were calculated to analyze their statistical characteristics, mainly including spatial and temporal distributions, variations and climatic trends of the two parameters of the durative heavy precipitation events in China. It is proved that these two parameters of heavy rainfall can display the temporal inhomogeneity in the precipitation field. And it is also found that there is a good positive relationship between the precipitation-concentration degree and annual rainfall amount in the Eastern and Central China. This method can be anolied in flood assessment and climate change fields.
基金jointly supported by the National Department Public Benefit Research Foundation(Grant No.GYHY201406003)the 973 Program(Grant Nos.2013CB956203 and 2012CB957803)+1 种基金the National Natural Science Foundation of China(Grant Nos.41490642,41475070 and 41305045)the Jiangsu Natural Science Foundation(Grant No.BK20151447)
文摘A regional heavy precipitation event that occurred over Sichuan Province on 8-9 September 2015 is analyzed based on hourly observed precipitation data obtained from weather stations and NCEP FNL data. Two moist dynamic parameters, i.e., moist vorticity (mζ and moist divergence (mδ), are used to diagnose this heavy precipitation event. Results show that the topography over southwestern China has a significant impact on the ability of these two parameters to diagnose precipitation. When the impact of topography is weak (i.e., low altitude), rn( cannot exactly depict the location of precipitation in the initial stage of the event. Then, as the precipitation develops, its ability to depict the location improves significantly. In particular, m( coincides best with the location of precipitation during the peak stage of the event. Besides, the evolution of the m( center shows high consistency with the evolution of the precipitation center. For mδ, although some false-alarm regions are apparent, it reflects the location of precipitation almost entirely during the precipitation event. However, the mδ center shows inconsistency with the precipitation center. These results suggest that both m( and mδ have a significant ability to predict the location of precipitation. Moreover, m( has a stronger ability than mδ in terms of predicting the variability of the precipitation center. However, when the impact of topography is strong (i.e., high altitude), both of these two moist dynamic parameters are unable to depict the location and center of precipitation during the entire precipitation event, suggesting their weak ability to predict precipitation over complex topography.
基金supported by the National Key R&D Program of China(Grant No.2018YFC1507703)the National Natural Science Foundation of China(Grant No.41675042)the Jiangsu Collaborative Innovation Center for Climate Change。
文摘In earlier studies,objective techniques have been used to determine the contribution of tropical cyclones to precipitation(TCP)in a region,where the Tropical cyclone Precipitation Event(TPE)and the Regional Heavy Precipitation Events(RHPEs)are defined and investigated.In this study,TPE and RHPEs are combined to determine the Typhoon Regional Heavy Precipitation Events(TRHPEs),which is employed to evaluate the contribution of tropical cyclones to regional extreme precipitation events.Based on the Objective Identification Technique for Regional Extreme Events(OITREE)and the Objective Synoptic Analysis Technique(OSAT)to define TPE,temporal and spatial overlap indices are developed to identify the combined events as TRHPE.With daily precipitation data and TC best-track data over the western North Pacific from 1960 to 2018,86 TRHPEs have been identified.TRHPEs contribute as much as 20%of the RHPEs,but100%of events with extreme individual precipitation intensities.The major TRHPEs continued for approximately a week after tropical cyclone landfall,indicating a role of post landfall precipitation.The frequency and extreme intensity of TRHPEs display increasing trends,consistent with an observed positive trend in the mean intensity of TPEs as measured by the number of daily station precipitation observations exceeding 100 mm and 250 mm.More frequent landfalling Southeast and South China TCs induced more serious impacts in coastal areas in the Southeast and the South during 1990-2018 than1960-89.The roles of cyclone translation speed and"shifts"in cyclone tracks are examined as possible explanations for the temporal trends.
基金Supported by New Meteorological Technology Promotion Program (CMATG2010Y16)Guangxi Natural Fund Program (2010GXNSFA013012)
文摘[Objective] The aim was to analyze one strong precipitation process in Northern Guangxi from May 27 to 28 in 2010.[Method] By dint of 2.5×2.5 NCEP reanalysis data,physical quantities such as the water vapor flux,pseudo-equivalent temperature,Non-geotropic wet Q vector in one front rainstorm process in north Guangxi from May 27 to 28 in 2010 was expounded.The forecast application of Non-geotropic wet Q vector in rainstorm falling area in Guangxi during early flood period was discussed.[Result] The water vapor in Bay of Bengal transported to Guangxi and formed convergence lifting movement in north Guangxi,which provided favorable water vapor transportation condition for the generation of strong precipitation in north Guangxi.The 850 hPa pseudo-equivalent temperature front (close area) moved southward to the north part of Guangxi.North Guangxi was in pseudo-equivalent temperature area.The highly wet unstable energy of lower layer and the cold air penetrating downward from the middle layer led to potential instability in the lower level established in northern Guangxi,which thus provided certain thermal condition for the strong precipitation process;Northern Guangxi was in the overlap region of the maximum gradient region of contour Qx at 850 hPa and stronger negative areas of ▽Q,which provided favorable dynamic condition for the rainstorm process in northern Guangxi in the future.[Conclusion] The study provided reference in accordance to the forecast of rainstorm.
文摘Soil washing, ex situ mechanical technique, is one of the few permanent treatment alternatives to remove metal contaminants from soils by employing physical separation based on mineral processing technologies to remove discrete particles or metal-bearing particles and/or chemical extraction based on leaching or dissolving process to extract the metals from the soils into an aqueous solution. However, washwater remained from soil washing process contains discrete particulate particles along with heavy metals as solution phase to be treated separately, as well as this process can produce large amount of sludge that requires further treatment, slow metal precipitation, poor settling, the aggregation of metal precipitates. Electrical treatments including electrocoagulation and electrolysis can be effective in removing these substances from washwater. This paper reviews the theoretical models in applying electrocoagulation and electrolysis to remove heavy metals and discrete particulate particles in washwater by examining and comparing the status of washwater treatment technologies which have been undertaken, mostly in the US and EU for the period 1990-2012.
基金supported by the National Department Public Benefit Research Foundation[grant number GYHY201406003]the Open Research Fund Program of the Plateau Atmosphere and Environment Key Laboratory of Sichuan Province[grant number PAEKL-2015-K3]+2 种基金the National Natural Science Foundation of China[grant numbers 413750544157506441375052]
基金supported by the Special Scientific Research Fund of the Meteorological Public Welfare of the Ministry of Sciences and Technology,China(Grant No.GYHY201406003)the National Natural Science Foundation of China(Grant Nos.41375054,41575064,and 41375052)+1 种基金the Applied Basic Research Programs of the Science and Technology Department of Sichuan Province(Grant No.2015JY0109)the Starting Foundation of Civil Aviation University of China(Grant No.2016QD05X)
基金"Variations of Extremely Heavy Precipitation and Their Response to Global Climate Change",a project in Research Fund for the Science of Tropical Marine and Meteorology(200804)"On the Regional Extremely Heavy Rain in South China Under the Background of Climate Warming,a project in Special China Meteorological Administration Program for Climate Change(CCSF-09-03)Assessment Report on the Climate Change in the South China Region(CCSF-09-11)
文摘This paper comprehensively studies the spatio-temporal characteristics of the frequency of extremely heavy precipitation events over South China by using the daily precipitation data of 110 stations during 1961 to 2008 and the extremely heavy precipitation thresholds determined for different stations by REOF, trend coefficients, linear trend, Mann-Kendall test and variance analysis. The results are shown as follows. The frequency distribution of extremely heavy precipitation is high in the middle of South China and low in the Guangdong coast and western Guangxi. There are three spatial distribution types of extremely heavy precipitation in South China. The consistent anomaly distribution is the main type. Distribution reversed between the east and the west and between the south and the north is also an important type. Extremely heavy precipitation events in South China mainly occurred in the summer-half of the year. Their frequency during this time accounts for 83.7% of the total frequency. In the 1960 s and 1980 s, extremely heavy precipitation events were less frequent while having an increasing trend from the late 1980 s. Their climatological tendency rates decrease in the central and rise in the other areas of South China, and on average the mean series also shows an upward but insignificant trend at all of the stations. South China's frequency of extremely heavy precipitation events can be divided into six major areas and each of them shows a different inter-annual trend and three of the representative stations experience abrupt changes by showing remarkable increases in terms of Mann-Kendall tests.
基金jointly supported by the National Natural Science Foundation of China[grant numbers 41305061 and41210007]the CAS-PKU(Chinese Academy of Sciences-Peking University)Joint Research Program
基金Supported by Special Project for Forecasters of China Meteorological Administration(CMAYBY2019-109)Scientific Research Project of Qujing Meteorological Bureau(2018-05)
文摘Based on the observation data from the automatic rainfall station and NCEP/NCAR reanalysis data,circulation analysis and diagnosis analysis of potential vorticity in a heavy rainfall process in September 2017 in Qujing were conducted.The results show that the heavy rainfall was mainly affected by the convergence zone between the two high pressures and shear line system,the precipitation area developed from the west to the southeast of Qujing,and the heavy rainfall area was concentrated in the central area.The southerly airflow in the middle and lower layers of the troposphere provided favorable water vapor conditions for heavy precipitation.The precipitation was characterized by high intensity,strong suddenness and small time scale.The heavy precipitation was concentrated from 04:00 to 06:00 on September 6.The high-and low-value centers of dry potential vorticity PV at 500 h Pa were indicative of the activities of cold and warm air in the process of heavy rainfall,and representative of the development of the convergence zone and the activities of shear line.That is to say,the high-value zone of dry potential vorticity PV at 500 h Pa was strengthened to penetrate into the center of Yunnan,leading the northerly airflow to the convergence zone.The deep southerly airflow in the relatively low-value zone of PV was uplifted to the north,converging the cold and warm air at the front of the convergence zone,resulting in heavy precipitation in Qujing.The high-value zone of wet potential vorticity MPV at 700 h Pa can also indicate the characteristics of unstable warm and humid air flow activity.MPV1<0,and MPV2>0,which easily caused the unstable energy release of wet convection and formed heavy precipitation.
基金funding from the National Natural Science Foundation of China(Grant 42022034,91737306,41675100)National Key Research and development Program of China(Grant No.2017YFA0604004)。
文摘Convective/large-scale(C/L)precipitation partitions are crucial for achieving realistic rainfall modeling and are classified in 16 phase 6 of the Coupled Model Intercomparison Project(CMIP6)atmospheric models.Only 4 models capture the feature that convective rainfall significantly exceeds the large-scale rainfall component in the tropics while the other 12 models show 50%–100%large-scale rainfall component in heavy rainfall.Increased horizontal resolution generally increases the convective rainfall percentage,but not in all models.The former 4 models can realistically reproduce two peaks of moisture vertical distribution,respectively located in the upper and the lower troposphere.In contrast,the latter 12 models correspond to three types of moisture vertical profile biases:(1)whole mid-to-lower tropospheric wet biases(60%–80%large-scale rainfall);(2)mid-tropospheric wet peak(50%convective/large-scale rainfall);and(3)lower-tropospheric wet peak(90%–100%large-scale rainfall).And the associated vertical distribution of unique clouds potentially causes different climate feedback,suggesting accurate C/L rainfall components are necessary to reliable climate projection.
基金Supported by the Science and Technology Research Projects of Gansu Meteorological Bureau(2013-14)
文摘[ Objective] The study aimed to discuss analyze climate change characteristics and return periods of heavy precipitation in the northeast side of Qinghai-Tibet Plateau. [ Method] Based on the data of daily precipitation from 1943 to 2008 in 6 representative meteorological stations in Linxia located in the northeast side of Qinghai-Tibet Plateau, the climate change characteristics of heavy precipitation were analyzed, and the return periods of heavy precipitation were calculated by Pearson-Ill probability distribution method. [ Result] Days of heavy precipitation in Linxia region in- creased conspicuously since the 1990s. The return periods of heavy precipitation in the six stations on August 20, 2008 were consistent with the re- sults of artificial estimation. [ Conclusion] The research could provide scientific references for the reasonable utilization of climate resources, disas- ter prevention and rational arranqement of anricultural plantina svstems in Linxia reaion.
基金the Project of Jiangxi Meteorological Bureau"Spatial and Temporal Distribution Characteristics and Classification of Heavy Rainstorm in Nanchang City".
文摘Based on the conventional observation data,dual polarization radar data and NCEP reanalysis data,the large-scale circulation background field,mesoscale conditions and formation causes of a heavy rainstorm in Nanchang on July 7,2020 were studied.It was found that this heavy rainstorm occurred under the weather background of the confrontation between the northward air flow behind the trough and the strong southwest warm and humid air flow to the northwest of the subtropical high.The divergence at the upper level,the shear in the middle and low levels,the southward movement of cold air at the low level,unusually abundant water vapor and high unstable energy caused the heavy rainstorm weather.In this process,under the influence of continuous eastward movement of several strong echo cells,an obvious"train effect"was formed in Nanchang,so that the local rainfall was continuous and intense.Moreover,the average of VIL was about 17 kg/m 2,and its variation characteristics were consistent with the variation trend of 5-min rainfall intensity,which had a certain indicator effect on short-term heavy precipitation.The topography of the Meiling Mountain in the west of Nanchang had a great influence on the formation and precipitation distribution of the heavy rain process.There was a strong rainstorm center near the mountain,and the precipitation was obviously larger than that in the plain area.
基金National Key R&D Program of China(2019YFC1510205)National Natural Science Foundation of China(41675042)。
文摘In this study,the Dynamical-Statistical-Analog Ensemble Forecast model(DSAEF_LTP model)for landfalling tropical cyclone(LTC)precipitation was employed to simulate the precipitation of 10 LTCs that occurred over China in 2018.With similarity region scheme(SRS)parameter values added and TC intensity introduced to the generalized initial value(GIV),four groups of precipitation simulation experiments were designed to verify the forecasting ability of the improved model for more TC samples.Results show that the simulation ability of the DSAEF_LTP model can be optimized regardless of whether adding SRS values only,or introducing TC intensity into GIV,while the experiment with both the two improvements shows a more prominent advantage in simulating the heavier precipitation of LTCs.Compared with four NWP models(i.e.,ECMWF,GFS,GRAPES and SMS-WARMS),the overall forecasting performance of the DSAEF_LTP model achieves a better result in simulating precipitation at the thresholds over 250 mm and performs slightly better than NWP models at the thresholds over 100 mm.