In recent years,torrential rain events caused by extratropical cyclones(ETCs)during the boreal midsummer(July-August)in Central and Eastern China have shown an increasing trend.For instence,in August 2024,two ETCs bro...In recent years,torrential rain events caused by extratropical cyclones(ETCs)during the boreal midsummer(July-August)in Central and Eastern China have shown an increasing trend.For instence,in August 2024,two ETCs brought large-scale heavy rainfall to North China,with daily precipitation exceeding 100 mm.Using reanalysis datasets and gridded precipitation data,the ETCs that affected Central and Eastern China during the boreal midsummer from 1981 to 2020 were objectively identified and tracked.ETCs causing precipitation were classified based on maximum daily precipitation,resulting in datasets for ETCs with torrential rain(daily precipitation exceeding 100 mm,referred to as ETC_R100)and heavy rain(daily precipitation exceeding 25 mm,referred to as ETC_R25).Comparative analysis can help highlight the characteristics of ETC_R100.This study compares the spatial distribution,movement paths,weather impacts,large-scale atmospheric circulation,and environmental conditions of these two types of precipitation-related ETCs.The following findings emerged:(1)ETC_R100 is driven by the combined forcing of upper-level troughs and warm-moist airflows at lower levels,exhibiting stronger thermal forcing than ETC_R25.(2)The moisture source for ETC_R100 are the Bay of Bengal and the Northwest Pacific,with moisture transported via the South China Sea.Compared to ETCs with nonextreme rainfall,ETC_R100 is characterized by greater atmospheric instability and better moisture conditions,resulting in higher precipitation intensity.(3)Regardless of the precipitation level,ETCs affected different regions but contributed significantly to precipitation in northern China,accounting for approximately 50%of the total precipitation.The results indicate that ETC_R100 differs significantly from ETCs with varying levels of precipitation in terms of statistical characteristics,weather impact,environmental conditions,and cyclogenesis conditions.展开更多
The impacts of cloud-induced mass forcing on the development of the moist potential vorticity (MPV) anomaly associated with torrential rains are investigated by using NCEP/NCAR 1? × 1? data. The MPV ten...The impacts of cloud-induced mass forcing on the development of the moist potential vorticity (MPV) anomaly associated with torrential rains are investigated by using NCEP/NCAR 1? × 1? data. The MPV tendency equation with the cloud-induced mass forcing is derived, and applied to the torrential rain event over the Changjiang River-Huaihe River Valleys during 26–30 June 1999. The result shows that positive anomalies are located mainly between 850 hPa and 500 hPa, while the maximum MPV, maximum positive tendency of the MPV, and maximum surface rainfall are nearly collocated. The cloud-induced mass forcing contributes to the positive tendency of the moist potential vorticity anomaly. The results indicate that the MPV may be used to track the propagation of rain systems for operational applications.展开更多
High-resolution numerical simulation data of a rainstorm triggering debris flow in Sichuan Province of China simulated by the Weather Research and Forecasting （WRF） Model were used to study the dominant cloud microp...High-resolution numerical simulation data of a rainstorm triggering debris flow in Sichuan Province of China simulated by the Weather Research and Forecasting （WRF） Model were used to study the dominant cloud microphysical processes of the torrential rainfall.The results showed that：（1） In the strong precipitation period,particle sizes of all hydrometeors increased,and mean-mass diameters of graupel increased the most significantly,as compared with those in the weak precipitation period; （2） The terminal velocity of raindrops was the strongest among all hydrometeors,followed by graupel＇s,which was much smaller than that of raindrops.Differences between various hydrometeors＇ terminal velocities in the strong precipitation period were larger than those in the weak precipitation period,which favored relative motion,collection interaction and transformation between the particles.Absolute terminal velocity values of raindrops and graupel were significantly greater than those of air upward velocity,and the stronger the precipitation was,the greater the differences between them were; （3） The orders of magnitudes of the various hydrometeors＇ sources and sinks in the strong precipitation period were larger than those in the weak precipitation period,causing a difference in the intensity of precipitation.Water vapor,cloud water,raindrops,graupel and their exchange processes played a major role in the production of the torrential rainfall,and there were two main processes via which raindrops were generated：abundant water vapor condensed into cloud water and,on the one hand,accretion of cloud water by rain water formed rain water,while on the other hand,accretion of cloud water by graupel formed graupel,and then the melting of graupel formed rain water.展开更多
Progress over the past decade in understanding moisture-driven dynamics and torrential rain storms in China is reviewed in this paper. First, advances in incorporating moisture effects more realistically into theory a...Progress over the past decade in understanding moisture-driven dynamics and torrential rain storms in China is reviewed in this paper. First, advances in incorporating moisture effects more realistically into theory are described, including the development of a new parameter, generalized moist potential vorticity（GMPV） and an improved moist ageostrophic Q vector（Qum）. Advances in vorticity dynamics are also described, including the adoption of a ＂parcel dynamic＂ approach to investigate the development of the vertical vorticity of an air parcel; a novel theory of slantwise vorticity development, proposed because vorticity develops easily near steep isentropic surfaces; and the development of the convective vorticity vector（CVV）as an effective new tool. The significant progress in both frontal dynamics and wave dynamics is also summarized, including the geostrophic adjustment of initial unbalanced flow and the dual role of boundary layer friction in frontogenesis, as well as the interaction between topography and fronts, which indicate that topographic perturbations alter both frontogenesis and frontal structure. For atmospheric vortices, mixed wave/vortex dynamics has been extended to explain the propagation of spiral rainbands and the development of dynamical instability in tropical cyclones. Finally, we review wave and basic flow interaction in torrential rainfall, for which it was necessary to extend existing theory from large-scale flows to mesoscale fields, enriching our knowledge of mesoscale atmospheric dynamics.展开更多
High-resolution data of a torrential rainfall event in Sichuan, China, simulated by the WRF model, were used to analyze the cloud microphysical differences with precipitation intensity. Sixhourly accumulated rainfall ...High-resolution data of a torrential rainfall event in Sichuan, China, simulated by the WRF model, were used to analyze the cloud microphysical differences with precipitation intensity. Sixhourly accumulated rainfall was classified into five bins based on rainfall intensity, and the cloud microphysical characteristics and processes in different bins were studied. The results show that：（1） Hydrometeor content differed distinctly among different bins. Mixing ratios of cloud water, rain water, and graupel enhanced significantly and monotonously with increasing rainfall intensity. With increasing precipitation intensity, the monotonous increase in cloud water number concentration was significant. Meanwhile, number concentrations of rain water and graupel increased at first and then decreased or increased slowly in larger rainfall bins.（2） With precipitation intensity increasing, cloud microphysical conversion processes closely related to the production of rainwater, directly（accretion of cloud water by rain（QCLcr） and melting of graupel（QMLgr）） or indirectly（water vapor condensation and accretion of cloud water by graupel）, increased significantly.（3） As the two main sources of rainwater, QCLcrincreased monotonously with increasing precipitation intensity, while QMLgr increased slowly, even tending to cease increasing in larger rainfall bins.展开更多
Warm-sector torrential rainfall(WSTR)events that occur in the annually first rainy season in south China are characterized by high rainfall intensity and low radar echo centroids.To understand the synoptic characteris...Warm-sector torrential rainfall(WSTR)events that occur in the annually first rainy season in south China are characterized by high rainfall intensity and low radar echo centroids.To understand the synoptic characteristics related to these features,16 WSTR events that occurred in 2013-2017 were examined with another 16 squall line(SL)events occurred during the same period as references.Composite analysis derived from ERA-Interim reanalysis data indicated the importance of the deep layer of warm and moist air for WSTR events.The most significant difference between WSTR and SL events lies in their low-level convergence and lifting;for WSTR events,the low-level convergence and lifting is much shallower with comparable or stronger intensity.The trumpet-shaped topography to the north of the WSTR centers is favorable for the development of such shallow convergences in WSTR events.Results in this study will provide references for future studies to improve the predictability of WSTR.展开更多
Day-to-day precipitation data of Juries during the 43 years of 1958-2000 from stations to the south of Yangtze River are used to divide regions and run statistical analysis of sustained torrential rainfall processes. ...Day-to-day precipitation data of Juries during the 43 years of 1958-2000 from stations to the south of Yangtze River are used to divide regions and run statistical analysis of sustained torrential rainfall processes. A preliminary analysis is then made based on it and the results show that June is the month in which torrential rains in the southern half of China take place frequently and sustained torrential rains occur at the same time in South China and the area to the south of Yangtze River. In addition, the analysis gives the basic features of sustained torrential rains of June in China and their interannual variability patterns, with the suggestion that the amount of these events increases significantly after the 1990s. Lastly, the sustained torrential rains occurring in Junes of 1994, 1998 and 2005 in the southern half of China are taken as examples in the research on the basic patterns and formation mechanisms of the evolution of double rain-bands during the rain season in South China and the area to the south of Yangtze River. The analysis shows that the large scale environment field in which sustained torrential rains occur is related to the stable sustaining of the South Asia High and upper level jet streams.展开更多
Predicting warm-sector torrential rainfall over South China,which is famous for its destructive power,is one of the most challenging issues of the current numerical forecast field.Insufficient understanding of the key...Predicting warm-sector torrential rainfall over South China,which is famous for its destructive power,is one of the most challenging issues of the current numerical forecast field.Insufficient understanding of the key mechanisms underlying this type of event is the root cause.Since understanding the energetics is crucial to understanding the evolutions of various types of weather systems,a general methodology for investigating energetics of torrential rainfall is provided in this study.By applying this methodology to a persistent torrential rainfall event which had concurrent frontal and warm-sector precipitation,the first physical image on the energetics of the warm-sector torrential rainfall is established.This clarifies the energy sources for producing the warm-sector rainfall during this event.For the first time,fundamental similarities and differences between the warm-sector and frontal torrential rainfall are shown in terms of energetics.It is found that these two types of rainfall mainly differed from each other in the lower-tropospheric dynamical features,and their key differences lay in energy sources.Scale interactions(mainly through downscale energy cascade and transport)were a dominant factor for the warm-sector torrential rainfall during this event,whereas,for the frontal torrential rainfall,they were only of secondary importance.Three typical signals in the background environment are found to have supplied energy to the warm-sector torrential rainfall,with the quasi-biweekly oscillation having contributed the most.展开更多
A rainfall that occurred during 0200–1400 Beijing Standard Time(BST)25 August 2008 shows the rapid development of a convective system,a short life span,and a record rate of 117.5 mm h-1for Xujiahui station since 1872...A rainfall that occurred during 0200–1400 Beijing Standard Time(BST)25 August 2008 shows the rapid development of a convective system,a short life span,and a record rate of 117.5 mm h-1for Xujiahui station since 1872.To study this torrential rainfall process,the partitioning method of Q vector is developed,in which a moist Q vector is first separated into a dry ageostrophic Q vector(DQ)and a diabatic-heating component.The dry ageostrophic Q vector is further partitioned along isothermal lines in the natural coordinate to identify different scale forcing in adiabatic atmosphere,and the large-scale and convective condensational heating in non-uniform saturated atmosphere,convective condensational heating, and Laplace of diabatic heating that includes radiative heating and other heating and cooling processes,are calculated to study the forcing from diabatic heating.The effects of the environmental conditions on the development of the rainfall processes are diagnosed by performing the partitioning of Q vector based on 6-hourly NCEP/NCAR Final Analysis(FNL)data with the horizontal resolution of 1°×1°.The results include the following:(1)a low-pressure inverted trough associated with the landfall of Typhoon Nuri (2008),a strong southwesterly jet along the western side of the subtropical high,and an eastward-propagating westerly low-pressure trough provide favorable synoptic conditions for the development of torrential rainfall;(2)the analysis of DQ vector showed that the upward motions forced by the convergence of DQ vector in the lower troposphere(1000–600 hPa)favor the development of torrential rainfall.When DQ vector converges in the upper troposphere(500–100 hPa),upward motions in the whole air column intensify significantly to accelerate the development of torrential rainfall;(3)the partitioning analysis of DQ vector reveals that large-scale forcing persistently favors the development of torrential rainfall whereas the mesoscale forcing speeds up the torrential rainfall;(4)the calculations of large-scale condensational heating in non-uniform saturated atmosphere,convective condensational heating, and Laplace of diabatic heating showed that the forcing related to diabatic heating has the positive feedback on the convective development,and such positive feedback decays and dissipates when the convective system propagates eastward and weakens.展开更多
One of the most vulnerable parts to natural hazards in Serbia is Kolubara river basin. In the past, during the period from 1929 to 2013, 121 torrential flood events in the Kolubara river basin were recorded which show...One of the most vulnerable parts to natural hazards in Serbia is Kolubara river basin. In the past, during the period from 1929 to 2013, 121 torrential flood events in the Kolubara river basin were recorded which show that this territory is extremely vulnerable to the torrential floods. The extreme event which occurred in May 2014 causing the catastrophic material damages and casualties was the latest and historical flood. The analysis of natural conditions in the Kolubara basin uniformly showed that this area is predisposed to a greater number of torrential floods due to its geomorphological, hydrological and land use properties. Torrential floods are closely related to the intensity and spatial distribution of erosive processes in the upper part of the Kolubara basin. The estimation of soil erosion potential is generally achieved by Erosion Potential Model(EPM). For the purposes of determining the degree of torrential properties in various water streams in the Kolubara basin, the calculation ofsusceptibility to torrential floods was assessed by Flash Flood Potential Index(FFPI). More than half of the basin area(57.2%) is located within the category of very weak and weak erosion(Z_(sr) = 0.35), but the category of medium erosion is geospatially very common. Such a distribution of medium erosion category provides conditions for generating, i.e. production of sediment which would boost torrential properties of water streams. After the classification of the obtained FFPI values it was determined that 25% of the Kolubara basin is very susceptible to torrents and this data should be seriously taken into consideration. Based on the analyses, the best and most successful manner of defence is prevention which consists of the integrated river basin management system(integrated torrent control system) so that technical works in hydrographic networks of torrents and biological and biotechnical works on the slope of the basin would be the best solution. Permanent control of erosive and torrential processes in the river basin will be not only important for flood control but it can also protect the existing and future water reservoirs and retentions fromsiltation with erosion sediment which is of great significance to the water management, agriculture, energy sector, and the entire society.展开更多
An extreme rainfall event occurred over Hangzhou,China,during the afternoon hours on 24 June 2013.This event occurred under suitable synoptic conditions and the maximum 4-h cumulative rainfall amount was over 150 mm.T...An extreme rainfall event occurred over Hangzhou,China,during the afternoon hours on 24 June 2013.This event occurred under suitable synoptic conditions and the maximum 4-h cumulative rainfall amount was over 150 mm.This rainfall event had two major rainbands.One was caused by a quasi-stationary convective line,and the other by a backbuilding convective line related to the interaction of the outflow boundary from the first rainband and an existing low-level mesoscale convergence line associated with a mei-yu frontal system.The rainfall event lasted 4 h,while the back-building process occurred in 2 h when the extreme rainfall center formed.So far,few studies have examined the back-building processes in the mei-yu season that are caused by the interaction of a mesoscale convergence line and a convective cold pool.The two rainbands are successfully reproduced by the Weather Research and Forecasting(WRF)model with fourlevel,two-way interactive nesting.In the model,new cells repeatedly occur at the west side of older cells,and the backbuilding process occurs in an environment with large CAPE,a low LFC,and plenty of water vapor.Outflows from older cells enhance the low-level convergence that forces new cells.High precipitation efficiency of the back-building training cells leads to accumulated precipitation of over 150 mm.Sensitivity experiments without evaporation of rainwater show that the convective cold pool plays an important role in the organization of the back-building process in the current extreme precipitation case.展开更多
NCEP-NCAR reanalysis data were used to analyze the characteristics and evolution mechanism of convective and symmetric instability before and during a heavy rainfall event that occurred in Beijing on 21 July 2012.Appr...NCEP-NCAR reanalysis data were used to analyze the characteristics and evolution mechanism of convective and symmetric instability before and during a heavy rainfall event that occurred in Beijing on 21 July 2012.Approximately twelve hours before the rainstorm,the atmosphere was mainly dominated by convective instability in the lower level of 900-800 hPa.The strong southwesterly low-level jet conveyed the moist and warm airflow continuously to the area of torrential rain,maintaining and enhancing the unstable energy.When the precipitation occurred,unstable energy was released and the convective instability weakened.Meanwhile,due to the baroclinicity enhancement in the atmosphere,the symmetric instability strengthened,maintaining and promoting the subsequent torrential rain.Deriving the convective instability tendency equation demonstrated that the barotropic component of potential divergence and the advection term played a major role in enhancing the convective instability before the rainstorm.Analysis of the tendency equation of moist potential vorticity showed that the coupled term of vertical vorticity and the baroclinic component of potential divergence was the primary factor influencing the development of symmetric instability during the precipitation.Comparing the effects of these factors on convective instability and symmetric instability showed some correlation.展开更多
A cloud-resolving model simulation of a mesoscale convective system （MCS） producing torrential rainfall is performed with the finest horizontal resolution of 444 m. It is shown that the model reproduces the observed...A cloud-resolving model simulation of a mesoscale convective system （MCS） producing torrential rainfall is performed with the finest horizontal resolution of 444 m. It is shown that the model reproduces the observed MCS, including its rainfall distribution and amounts, as well as the timing and location of leading rainbands and trailing stratiform clouds. Results show that discrete convective hot towers, shown in Vis5D at a scale of 2-5 kin, are triggered by evaporatively driven cold outflows converging with the high-θe air ahead. Then, they move rearward, with respect to the leading rainbands, to form stratiform clouds. These convective towers generate vortical tubes of opposite signs, with more intense cyclonic vorticity occurring in the leading convergence zone. The results appear to have important implications for the improvement of summertime quantitative precipitation forecasts and the understanding of vortical hot towers, as well midlevel mesoscale convective vortices.展开更多
This paper presents debris-flow numerical simulations using the Hyper KANAKO system,developed by the authors.The system uses the debris flow simulator KANAKO 2D equipped with a graphical user interface(GUI);hence,a us...This paper presents debris-flow numerical simulations using the Hyper KANAKO system,developed by the authors.The system uses the debris flow simulator KANAKO 2D equipped with a graphical user interface(GUI);hence,a user can easily produce appropriate landform data for simulations using standard laser profiler data,and visualize the results using a GIS.Hyper KANAKO was applied to the streams around Kiyomizu-dera in Kyoto,Japan.Kiyomizu-dera is a famous temple in Japan which is visited by numerous tourists throughout the year.We simulated a disaster scenario of debris flow caused by torrential rain.We set the hydrograph using rainfall intensity data,and set the landform data using information from the Geospatial Information Authority of Japan(GSI) and a digital elevation model(DEM).We evaluated different mesh sizes and also used a digital surface model(DSM) to consider the building heights.The simulation results showed that with small mesh size,the debris flowmoved through the roads,which seems realistic for a disaster situation.When buildings were considered,the flow direction changed,and a 1-m flow depth,which was deeper than in other cases,appeared in the flow path.This may pose a dangerous situation for evacuations.展开更多
Solute transport simulations are important in water pollution events.This paper introduces a finite volume Godunovtype model for solving a 4×4 matrix form of the hyperbolic conservation laws consisting of 2D shal...Solute transport simulations are important in water pollution events.This paper introduces a finite volume Godunovtype model for solving a 4×4 matrix form of the hyperbolic conservation laws consisting of 2D shallow water equations and transport equations.The model adopts the Harten-Lax-van Leer-contact(HLLC)-approximate Riemann solution to calculate the cell interface fluxes.It can deal well with the changes in the dry and wet interfaces in an actual complex terrain,and it has a strong shock-wave capturing ability.Using monotonic upstream-centred scheme for conservation laws(MUSCL)linear reconstruction with finite slope and the Runge-Kutta time integration method can achieve second-order accuracy.At the same time,the introduction of graphics processing unit(GPU)-accelerated computing technology greatly increases the computing speed.The model is validated against multiple benchmarks,and the results are in good agreement with analytical solutions and other published numerical predictions.The third test case uses the GPU and central processing unit(CPU)calculation models which take 3.865 s and 13.865 s,respectively,indicating that the GPU calculation model can increase the calculation speed by 3.6 times.In the fourth test case,comparing the numerical model calculated by GPU with the traditional numerical model calculated by CPU,the calculation efficiencies of the numerical model calculated by GPU under different resolution grids are 9.8–44.6 times higher than those by CPU.Therefore,it has better potential than previous models for large-scale simulation of solute transport in water pollution incidents.It can provide a reliable theoretical basis and strong data support in the rapid assessment and early warning of water pollution accidents.展开更多
The surface rainfall processes associated with the torrential rainfall event over Hubei,China,during July 2007 were investigated using a two-dimensional cloud-resolving model.The model integrated the large-scale verti...The surface rainfall processes associated with the torrential rainfall event over Hubei,China,during July 2007 were investigated using a two-dimensional cloud-resolving model.The model integrated the large-scale vertical velocity and zonal wind data from National Centers for Environmental Prediction（NCEP）/Global Data Assimilation System（GDAS） for 5 days.The time and model domain mean surface rain rate was used to identify the onset,mature,and decay periods of rainfall.During the onset period,the descending motion data imposed in the lower troposphere led to a large contribution of stratiform rainfall to the model domain mean surface rainfall.The local atmospheric drying and transport of rain from convective regions mainly contributes to the stratiform rainfall.During the mature periods,the ascending motion data integrated into the model was so strong that water vapor convergence was the dominant process for both convective and stratiform rainfall.Both convective and stratiform rainfalls made important contributions to the model domain mean surface rainfall.During the decay period,descending motion data input into the model prevailed,making stratiform rainfall dominant.Stratiform rainfall was mainly caused by the water vapor convergence over raining stratiform regions.展开更多
1 INTRODUCTION Locating between the southern temperate climate zone and northern subtropical climate zone, the basin of Huaihe River witnesses frequent occurrence of meteorological disasters, especially from May to Au...1 INTRODUCTION Locating between the southern temperate climate zone and northern subtropical climate zone, the basin of Huaihe River witnesses frequent occurrence of meteorological disasters, especially from May to August when heavy rains usually result in floods. There has been much research at home and abroad on the estimation of rainfall based on radar data and satellite imagery . Experiments on heavy rains are mainly, however, based on Type 713 weather radar, which limits quantitative estimation of rainfall. With data from a Doppler weather radar on the S band （CINRAD/SA） co-manufactured by China and U.S.A. in 1999, this work makes quantitative estimation of rainfall over the Anhui region in the Huaihe River valley, supplemented with GMS satellite data, records from weather stations and automatic rain gauges. A localized model and set of indices have been set up to utilize the CINRAD/SA radar and GMS satellite, flood-causing heavy rains are pre-warned and forecast with interpretations of the NWP product HLAFS, and a software ofpre-warning operation is finalized to watch this kind of rain over the valley.展开更多
A good representation of the interaction between the planetary boundary layer(PBL)and the surface layer(SL)in numerical models is of great importance for the prediction of the initiation and development of convection....A good representation of the interaction between the planetary boundary layer(PBL)and the surface layer(SL)in numerical models is of great importance for the prediction of the initiation and development of convection.This study examined an ensemble that consists of the available suites of PBL and SL parameterizations based on a torrential rainfall event over south China.The sensitivity of the simulations was investigated against objective measurements using multiple PBL and SL parameterization schemes.The main causes of the bias from different parameterization schemes were further analysed by comparing the good and bad ensemble members.The results showed that good members tended to underestimate the rainfall amount but presented a decent evolution of mesoscale convective systems that were responsible for the torrential rainfall.Using the total energy mass flux(TEMF)scheme,the bad members overestimated the amount and spatial coverage of rainfall.The failure of the bad member was due to a spurious convection initiation(CI)resulting from the overestimated high-θe elevated air.The spurious CI developed and expanded rapidly,causing intensive and extensive rainfall over south China.Consistent with previous studies,the TEMF scheme tends to produce a warmer and moister PBL environment.The detailed sensitivity analysis of this case may provide reference for the operational forecast of rainfall over south China using multiple PBL and SL parameterizations.展开更多
Based on the conventional ground observational data,a numerical simulation and moist potential vorticity( MPV) analysis has been carried on heavy rainfall event over Jiangxi province from 19 June to 20 June 2010,with ...Based on the conventional ground observational data,a numerical simulation and moist potential vorticity( MPV) analysis has been carried on heavy rainfall event over Jiangxi province from 19 June to 20 June 2010,with a meso-scale rainstorm model. The results show that this rare rainstorm is a typical heavy rainfall over Meiyu front. The cold air flow behind North China vortex joined up the southwestern flow located in the northwest part of the strong and stable subtropical high,thus the cold air and warm air converged and maintained over the northern part of Hunan and Jiangxi province. The simulated precipitation of the high resolution model is very similar to the observational rainfall. The model has a good predictive skill for the location,intensity and center of heavy rainfall. By moist potential vorticity analysis,it is found that the distribution characteristic of MPV which heavy rainfall happens ahead has an obvious indication for precipitation forecast. The vertical overlapping of the positive and negative MPV1 areas is favorable to the generation and development of rainstorm. This zone is also the conjoint area of convective instability and baroclinic instability.展开更多
The quasi 11-year cycle of sunspot activities and torrential rain days in Fuxin during 1951-2005 were studied.As was shown in the results,the relative number of sunspots and the torrential rain days in the sunspot cyc...The quasi 11-year cycle of sunspot activities and torrential rain days in Fuxin during 1951-2005 were studied.As was shown in the results,the relative number of sunspots and the torrential rain days in the sunspot cycle of trough value were significantly related with a correlation coefficient of 0.842.At the same time,the correlation coefficient between torrential rain days in Fuxin and the relative number of sunspots of certain year within the sunspot cycle of trough value reached 0.737.It was clear that the torrential rain days in Fuxin were closely related with solar activity.The conclusion would provide the favorable climate background and basis for the study of regularity of rainstorm outbreak,monitoring and forecasting of torrential rain and regularity of agricultural drought and flood.展开更多
基金National Natural Science Foundation of China(42375014,42088101,42030605)Joint Research Project for Meteorological Capacity Improvement(24NLTSZ010)Young Elite Scientists Sponsorship Program by BAST(BYESS2023205)。
文摘In recent years,torrential rain events caused by extratropical cyclones(ETCs)during the boreal midsummer(July-August)in Central and Eastern China have shown an increasing trend.For instence,in August 2024,two ETCs brought large-scale heavy rainfall to North China,with daily precipitation exceeding 100 mm.Using reanalysis datasets and gridded precipitation data,the ETCs that affected Central and Eastern China during the boreal midsummer from 1981 to 2020 were objectively identified and tracked.ETCs causing precipitation were classified based on maximum daily precipitation,resulting in datasets for ETCs with torrential rain(daily precipitation exceeding 100 mm,referred to as ETC_R100)and heavy rain(daily precipitation exceeding 25 mm,referred to as ETC_R25).Comparative analysis can help highlight the characteristics of ETC_R100.This study compares the spatial distribution,movement paths,weather impacts,large-scale atmospheric circulation,and environmental conditions of these two types of precipitation-related ETCs.The following findings emerged:(1)ETC_R100 is driven by the combined forcing of upper-level troughs and warm-moist airflows at lower levels,exhibiting stronger thermal forcing than ETC_R25.(2)The moisture source for ETC_R100 are the Bay of Bengal and the Northwest Pacific,with moisture transported via the South China Sea.Compared to ETCs with nonextreme rainfall,ETC_R100 is characterized by greater atmospheric instability and better moisture conditions,resulting in higher precipitation intensity.(3)Regardless of the precipitation level,ETCs affected different regions but contributed significantly to precipitation in northern China,accounting for approximately 50%of the total precipitation.The results indicate that ETC_R100 differs significantly from ETCs with varying levels of precipitation in terms of statistical characteristics,weather impact,environmental conditions,and cyclogenesis conditions.
基金by the National Natural Science Foundation of China under Grant Nos.40405007 , 40275015 the OlympicProject under Grant No.KACX1-02 partially sup-ported by the"Outstanding Overseas Chinese Scholars"Project of the Chinese Academy of Sciences under Grant No.2002-1-2.
文摘The impacts of cloud-induced mass forcing on the development of the moist potential vorticity (MPV) anomaly associated with torrential rains are investigated by using NCEP/NCAR 1? × 1? data. The MPV tendency equation with the cloud-induced mass forcing is derived, and applied to the torrential rain event over the Changjiang River-Huaihe River Valleys during 26–30 June 1999. The result shows that positive anomalies are located mainly between 850 hPa and 500 hPa, while the maximum MPV, maximum positive tendency of the MPV, and maximum surface rainfall are nearly collocated. The cloud-induced mass forcing contributes to the positive tendency of the moist potential vorticity anomaly. The results indicate that the MPV may be used to track the propagation of rain systems for operational applications.
基金supported by the Key Research Program of the Chinese Academy of Sciences (Grant No. KZZD-EW-05-01)the National Basic Research Program of China (973 Program) (Grant No. 2014CB441402)
文摘High-resolution numerical simulation data of a rainstorm triggering debris flow in Sichuan Province of China simulated by the Weather Research and Forecasting （WRF） Model were used to study the dominant cloud microphysical processes of the torrential rainfall.The results showed that：（1） In the strong precipitation period,particle sizes of all hydrometeors increased,and mean-mass diameters of graupel increased the most significantly,as compared with those in the weak precipitation period; （2） The terminal velocity of raindrops was the strongest among all hydrometeors,followed by graupel＇s,which was much smaller than that of raindrops.Differences between various hydrometeors＇ terminal velocities in the strong precipitation period were larger than those in the weak precipitation period,which favored relative motion,collection interaction and transformation between the particles.Absolute terminal velocity values of raindrops and graupel were significantly greater than those of air upward velocity,and the stronger the precipitation was,the greater the differences between them were; （3） The orders of magnitudes of the various hydrometeors＇ sources and sinks in the strong precipitation period were larger than those in the weak precipitation period,causing a difference in the intensity of precipitation.Water vapor,cloud water,raindrops,graupel and their exchange processes played a major role in the production of the torrential rainfall,and there were two main processes via which raindrops were generated：abundant water vapor condensed into cloud water and,on the one hand,accretion of cloud water by rain water formed rain water,while on the other hand,accretion of cloud water by graupel formed graupel,and then the melting of graupel formed rain water.
基金supported by the National Natural Science Foundation of China (Grant Nos. 91437215 and 41375052)State Key Laboratory of Severe Weather Open Project (Grant No. 2013LASW-A06)the Key Research Program of the Chinese Academy of Sciences (Grant No. KZZD-EW05-01)
文摘Progress over the past decade in understanding moisture-driven dynamics and torrential rain storms in China is reviewed in this paper. First, advances in incorporating moisture effects more realistically into theory are described, including the development of a new parameter, generalized moist potential vorticity（GMPV） and an improved moist ageostrophic Q vector（Qum）. Advances in vorticity dynamics are also described, including the adoption of a ＂parcel dynamic＂ approach to investigate the development of the vertical vorticity of an air parcel; a novel theory of slantwise vorticity development, proposed because vorticity develops easily near steep isentropic surfaces; and the development of the convective vorticity vector（CVV）as an effective new tool. The significant progress in both frontal dynamics and wave dynamics is also summarized, including the geostrophic adjustment of initial unbalanced flow and the dual role of boundary layer friction in frontogenesis, as well as the interaction between topography and fronts, which indicate that topographic perturbations alter both frontogenesis and frontal structure. For atmospheric vortices, mixed wave/vortex dynamics has been extended to explain the propagation of spiral rainbands and the development of dynamical instability in tropical cyclones. Finally, we review wave and basic flow interaction in torrential rainfall, for which it was necessary to extend existing theory from large-scale flows to mesoscale fields, enriching our knowledge of mesoscale atmospheric dynamics.
基金supported by the Key Research Program of the Chinese Academy of Sciences[grant number KZZD-e W-05-01]the National Basic Research Program of China[973 Program,grant number 2014CB441402]
文摘High-resolution data of a torrential rainfall event in Sichuan, China, simulated by the WRF model, were used to analyze the cloud microphysical differences with precipitation intensity. Sixhourly accumulated rainfall was classified into five bins based on rainfall intensity, and the cloud microphysical characteristics and processes in different bins were studied. The results show that：（1） Hydrometeor content differed distinctly among different bins. Mixing ratios of cloud water, rain water, and graupel enhanced significantly and monotonously with increasing rainfall intensity. With increasing precipitation intensity, the monotonous increase in cloud water number concentration was significant. Meanwhile, number concentrations of rain water and graupel increased at first and then decreased or increased slowly in larger rainfall bins.（2） With precipitation intensity increasing, cloud microphysical conversion processes closely related to the production of rainwater, directly（accretion of cloud water by rain（QCLcr） and melting of graupel（QMLgr）） or indirectly（water vapor condensation and accretion of cloud water by graupel）, increased significantly.（3） As the two main sources of rainwater, QCLcrincreased monotonously with increasing precipitation intensity, while QMLgr increased slowly, even tending to cease increasing in larger rainfall bins.
基金National Key R&D Program of China(2018YFC1507402)National Natural Science Foundation of China(41875168,U1811464)Science and Technology Planning Project of Guangzhou(201605131033247)。
文摘Warm-sector torrential rainfall(WSTR)events that occur in the annually first rainy season in south China are characterized by high rainfall intensity and low radar echo centroids.To understand the synoptic characteristics related to these features,16 WSTR events that occurred in 2013-2017 were examined with another 16 squall line(SL)events occurred during the same period as references.Composite analysis derived from ERA-Interim reanalysis data indicated the importance of the deep layer of warm and moist air for WSTR events.The most significant difference between WSTR and SL events lies in their low-level convergence and lifting;for WSTR events,the low-level convergence and lifting is much shallower with comparable or stronger intensity.The trumpet-shaped topography to the north of the WSTR centers is favorable for the development of such shallow convergences in WSTR events.Results in this study will provide references for future studies to improve the predictability of WSTR.
基金National Fundamental Research Development Project for Programme "973" (2004CB418303)
文摘Day-to-day precipitation data of Juries during the 43 years of 1958-2000 from stations to the south of Yangtze River are used to divide regions and run statistical analysis of sustained torrential rainfall processes. A preliminary analysis is then made based on it and the results show that June is the month in which torrential rains in the southern half of China take place frequently and sustained torrential rains occur at the same time in South China and the area to the south of Yangtze River. In addition, the analysis gives the basic features of sustained torrential rains of June in China and their interannual variability patterns, with the suggestion that the amount of these events increases significantly after the 1990s. Lastly, the sustained torrential rains occurring in Junes of 1994, 1998 and 2005 in the southern half of China are taken as examples in the research on the basic patterns and formation mechanisms of the evolution of double rain-bands during the rain season in South China and the area to the south of Yangtze River. The analysis shows that the large scale environment field in which sustained torrential rains occur is related to the stable sustaining of the South Asia High and upper level jet streams.
基金supported by the National Key R&D Program of China (Grant No. 2018YFC1507400)the National Natural Science Foundation of China (Grant Nos. 42075002 and 42030610)
文摘Predicting warm-sector torrential rainfall over South China,which is famous for its destructive power,is one of the most challenging issues of the current numerical forecast field.Insufficient understanding of the key mechanisms underlying this type of event is the root cause.Since understanding the energetics is crucial to understanding the evolutions of various types of weather systems,a general methodology for investigating energetics of torrential rainfall is provided in this study.By applying this methodology to a persistent torrential rainfall event which had concurrent frontal and warm-sector precipitation,the first physical image on the energetics of the warm-sector torrential rainfall is established.This clarifies the energy sources for producing the warm-sector rainfall during this event.For the first time,fundamental similarities and differences between the warm-sector and frontal torrential rainfall are shown in terms of energetics.It is found that these two types of rainfall mainly differed from each other in the lower-tropospheric dynamical features,and their key differences lay in energy sources.Scale interactions(mainly through downscale energy cascade and transport)were a dominant factor for the warm-sector torrential rainfall during this event,whereas,for the frontal torrential rainfall,they were only of secondary importance.Three typical signals in the background environment are found to have supplied energy to the warm-sector torrential rainfall,with the quasi-biweekly oscillation having contributed the most.
基金National Natural Science Foundation of China(40875025,40875030,40775033,40921160381)Shanghai Natural Science Foundation of China(08ZR1422900)Key Promotion Project of New Meteorology Technology of the China Meteorological Administration in 2009(09A13)
文摘A rainfall that occurred during 0200–1400 Beijing Standard Time(BST)25 August 2008 shows the rapid development of a convective system,a short life span,and a record rate of 117.5 mm h-1for Xujiahui station since 1872.To study this torrential rainfall process,the partitioning method of Q vector is developed,in which a moist Q vector is first separated into a dry ageostrophic Q vector(DQ)and a diabatic-heating component.The dry ageostrophic Q vector is further partitioned along isothermal lines in the natural coordinate to identify different scale forcing in adiabatic atmosphere,and the large-scale and convective condensational heating in non-uniform saturated atmosphere,convective condensational heating, and Laplace of diabatic heating that includes radiative heating and other heating and cooling processes,are calculated to study the forcing from diabatic heating.The effects of the environmental conditions on the development of the rainfall processes are diagnosed by performing the partitioning of Q vector based on 6-hourly NCEP/NCAR Final Analysis(FNL)data with the horizontal resolution of 1°×1°.The results include the following:(1)a low-pressure inverted trough associated with the landfall of Typhoon Nuri (2008),a strong southwesterly jet along the western side of the subtropical high,and an eastward-propagating westerly low-pressure trough provide favorable synoptic conditions for the development of torrential rainfall;(2)the analysis of DQ vector showed that the upward motions forced by the convergence of DQ vector in the lower troposphere(1000–600 hPa)favor the development of torrential rainfall.When DQ vector converges in the upper troposphere(500–100 hPa),upward motions in the whole air column intensify significantly to accelerate the development of torrential rainfall;(3)the partitioning analysis of DQ vector reveals that large-scale forcing persistently favors the development of torrential rainfall whereas the mesoscale forcing speeds up the torrential rainfall;(4)the calculations of large-scale condensational heating in non-uniform saturated atmosphere,convective condensational heating, and Laplace of diabatic heating showed that the forcing related to diabatic heating has the positive feedback on the convective development,and such positive feedback decays and dissipates when the convective system propagates eastward and weakens.
基金part of the project "The Research on Climate Change Influences on Environment: Influence Monitoring, Adaptation and Mitigation" (43007), subproject No. 9: "Torrential Floods Frequency, Soil and Water Degradation as the Consequence of Global Changes"financed by Ministry of Education, Science and Technological Development of the Republic of Serbia as part of the Integrated and Interdisciplinary Researches programme for the period from 2011 to 2017
文摘One of the most vulnerable parts to natural hazards in Serbia is Kolubara river basin. In the past, during the period from 1929 to 2013, 121 torrential flood events in the Kolubara river basin were recorded which show that this territory is extremely vulnerable to the torrential floods. The extreme event which occurred in May 2014 causing the catastrophic material damages and casualties was the latest and historical flood. The analysis of natural conditions in the Kolubara basin uniformly showed that this area is predisposed to a greater number of torrential floods due to its geomorphological, hydrological and land use properties. Torrential floods are closely related to the intensity and spatial distribution of erosive processes in the upper part of the Kolubara basin. The estimation of soil erosion potential is generally achieved by Erosion Potential Model(EPM). For the purposes of determining the degree of torrential properties in various water streams in the Kolubara basin, the calculation ofsusceptibility to torrential floods was assessed by Flash Flood Potential Index(FFPI). More than half of the basin area(57.2%) is located within the category of very weak and weak erosion(Z_(sr) = 0.35), but the category of medium erosion is geospatially very common. Such a distribution of medium erosion category provides conditions for generating, i.e. production of sediment which would boost torrential properties of water streams. After the classification of the obtained FFPI values it was determined that 25% of the Kolubara basin is very susceptible to torrents and this data should be seriously taken into consideration. Based on the analyses, the best and most successful manner of defence is prevention which consists of the integrated river basin management system(integrated torrent control system) so that technical works in hydrographic networks of torrents and biological and biotechnical works on the slope of the basin would be the best solution. Permanent control of erosive and torrential processes in the river basin will be not only important for flood control but it can also protect the existing and future water reservoirs and retentions fromsiltation with erosion sediment which is of great significance to the water management, agriculture, energy sector, and the entire society.
基金supported by the National Natural Science Foundation of China (Grant Nos.41730965, U2242204, and 41175047)the National Key Basic Research and Development Project of China (Grant No.2013CB430104)+2 种基金the Key Project of the Joint Funds of the Natural Science Foundation of Zhejiang Province (Grant No.LZJMZ23D050003financial support from the China Scholarship Council for her visit to CAPSUniversity of Oklahoma
文摘An extreme rainfall event occurred over Hangzhou,China,during the afternoon hours on 24 June 2013.This event occurred under suitable synoptic conditions and the maximum 4-h cumulative rainfall amount was over 150 mm.This rainfall event had two major rainbands.One was caused by a quasi-stationary convective line,and the other by a backbuilding convective line related to the interaction of the outflow boundary from the first rainband and an existing low-level mesoscale convergence line associated with a mei-yu frontal system.The rainfall event lasted 4 h,while the back-building process occurred in 2 h when the extreme rainfall center formed.So far,few studies have examined the back-building processes in the mei-yu season that are caused by the interaction of a mesoscale convergence line and a convective cold pool.The two rainbands are successfully reproduced by the Weather Research and Forecasting(WRF)model with fourlevel,two-way interactive nesting.In the model,new cells repeatedly occur at the west side of older cells,and the backbuilding process occurs in an environment with large CAPE,a low LFC,and plenty of water vapor.Outflows from older cells enhance the low-level convergence that forces new cells.High precipitation efficiency of the back-building training cells leads to accumulated precipitation of over 150 mm.Sensitivity experiments without evaporation of rainwater show that the convective cold pool plays an important role in the organization of the back-building process in the current extreme precipitation case.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41175060 and 41375052)the Key Program of the Chinese Academy of Sciences (Grant No. KZZD-EW-05)+1 种基金the National Basic Research Program of China (Grant No. 2013CB430105)the State Key Laboratory of Severe Weather (LASW),Chinese Academy of Meteorological Sciences (Grant No. 2013LASW-A06)
文摘NCEP-NCAR reanalysis data were used to analyze the characteristics and evolution mechanism of convective and symmetric instability before and during a heavy rainfall event that occurred in Beijing on 21 July 2012.Approximately twelve hours before the rainstorm,the atmosphere was mainly dominated by convective instability in the lower level of 900-800 hPa.The strong southwesterly low-level jet conveyed the moist and warm airflow continuously to the area of torrential rain,maintaining and enhancing the unstable energy.When the precipitation occurred,unstable energy was released and the convective instability weakened.Meanwhile,due to the baroclinicity enhancement in the atmosphere,the symmetric instability strengthened,maintaining and promoting the subsequent torrential rain.Deriving the convective instability tendency equation demonstrated that the barotropic component of potential divergence and the advection term played a major role in enhancing the convective instability before the rainstorm.Analysis of the tendency equation of moist potential vorticity showed that the coupled term of vertical vorticity and the baroclinic component of potential divergence was the primary factor influencing the development of symmetric instability during the precipitation.Comparing the effects of these factors on convective instability and symmetric instability showed some correlation.
基金supported by Jiangsu Education Science Foundation (Grant No.07KJB170065)Chinese National Science Foundation (Grant No.40775060)U.S.National Science Foundation (Grant No.ATM0758609)
文摘A cloud-resolving model simulation of a mesoscale convective system （MCS） producing torrential rainfall is performed with the finest horizontal resolution of 444 m. It is shown that the model reproduces the observed MCS, including its rainfall distribution and amounts, as well as the timing and location of leading rainbands and trailing stratiform clouds. Results show that discrete convective hot towers, shown in Vis5D at a scale of 2-5 kin, are triggered by evaporatively driven cold outflows converging with the high-θe air ahead. Then, they move rearward, with respect to the leading rainbands, to form stratiform clouds. These convective towers generate vortical tubes of opposite signs, with more intense cyclonic vorticity occurring in the leading convergence zone. The results appear to have important implications for the improvement of summertime quantitative precipitation forecasts and the understanding of vortical hot towers, as well midlevel mesoscale convective vortices.
基金supported by JSPS KAKENHI Grant No.24710206,Grant-in-Aid for Young Scientists (B)
文摘This paper presents debris-flow numerical simulations using the Hyper KANAKO system,developed by the authors.The system uses the debris flow simulator KANAKO 2D equipped with a graphical user interface(GUI);hence,a user can easily produce appropriate landform data for simulations using standard laser profiler data,and visualize the results using a GIS.Hyper KANAKO was applied to the streams around Kiyomizu-dera in Kyoto,Japan.Kiyomizu-dera is a famous temple in Japan which is visited by numerous tourists throughout the year.We simulated a disaster scenario of debris flow caused by torrential rain.We set the hydrograph using rainfall intensity data,and set the landform data using information from the Geospatial Information Authority of Japan(GSI) and a digital elevation model(DEM).We evaluated different mesh sizes and also used a digital surface model(DSM) to consider the building heights.The simulation results showed that with small mesh size,the debris flowmoved through the roads,which seems realistic for a disaster situation.When buildings were considered,the flow direction changed,and a 1-m flow depth,which was deeper than in other cases,appeared in the flow path.This may pose a dangerous situation for evacuations.
基金Project supported by the National Natural Science Foundation of China(Nos.52009104 and 52079106)the Shaanxi Provincial Department of Water Resources Project(No.2017slkj-14)the Shaanxi Provincial Department of Science and Technology Project(No.2017JQ3043),China。
文摘Solute transport simulations are important in water pollution events.This paper introduces a finite volume Godunovtype model for solving a 4×4 matrix form of the hyperbolic conservation laws consisting of 2D shallow water equations and transport equations.The model adopts the Harten-Lax-van Leer-contact(HLLC)-approximate Riemann solution to calculate the cell interface fluxes.It can deal well with the changes in the dry and wet interfaces in an actual complex terrain,and it has a strong shock-wave capturing ability.Using monotonic upstream-centred scheme for conservation laws(MUSCL)linear reconstruction with finite slope and the Runge-Kutta time integration method can achieve second-order accuracy.At the same time,the introduction of graphics processing unit(GPU)-accelerated computing technology greatly increases the computing speed.The model is validated against multiple benchmarks,and the results are in good agreement with analytical solutions and other published numerical predictions.The third test case uses the GPU and central processing unit(CPU)calculation models which take 3.865 s and 13.865 s,respectively,indicating that the GPU calculation model can increase the calculation speed by 3.6 times.In the fourth test case,comparing the numerical model calculated by GPU with the traditional numerical model calculated by CPU,the calculation efficiencies of the numerical model calculated by GPU under different resolution grids are 9.8–44.6 times higher than those by CPU.Therefore,it has better potential than previous models for large-scale simulation of solute transport in water pollution incidents.It can provide a reliable theoretical basis and strong data support in the rapid assessment and early warning of water pollution accidents.
基金supported by the Project of the Ministry of Sciences and Technology of the People’s Republic of China (Grant No. GYHY200906004)the Projects of the Natural Science Foundation of China (Grant Nos. 41075044 and 41075079)
文摘The surface rainfall processes associated with the torrential rainfall event over Hubei,China,during July 2007 were investigated using a two-dimensional cloud-resolving model.The model integrated the large-scale vertical velocity and zonal wind data from National Centers for Environmental Prediction（NCEP）/Global Data Assimilation System（GDAS） for 5 days.The time and model domain mean surface rain rate was used to identify the onset,mature,and decay periods of rainfall.During the onset period,the descending motion data imposed in the lower troposphere led to a large contribution of stratiform rainfall to the model domain mean surface rainfall.The local atmospheric drying and transport of rain from convective regions mainly contributes to the stratiform rainfall.During the mature periods,the ascending motion data integrated into the model was so strong that water vapor convergence was the dominant process for both convective and stratiform rainfall.Both convective and stratiform rainfalls made important contributions to the model domain mean surface rainfall.During the decay period,descending motion data input into the model prevailed,making stratiform rainfall dominant.Stratiform rainfall was mainly caused by the water vapor convergence over raining stratiform regions.
基金Research on Floods-Causing Heavy Rains Based on CINRAD/SA, a public wellbeing projectfrom the Ministry of Science and Technology (2000 DIB20103)
文摘1 INTRODUCTION Locating between the southern temperate climate zone and northern subtropical climate zone, the basin of Huaihe River witnesses frequent occurrence of meteorological disasters, especially from May to August when heavy rains usually result in floods. There has been much research at home and abroad on the estimation of rainfall based on radar data and satellite imagery . Experiments on heavy rains are mainly, however, based on Type 713 weather radar, which limits quantitative estimation of rainfall. With data from a Doppler weather radar on the S band （CINRAD/SA） co-manufactured by China and U.S.A. in 1999, this work makes quantitative estimation of rainfall over the Anhui region in the Huaihe River valley, supplemented with GMS satellite data, records from weather stations and automatic rain gauges. A localized model and set of indices have been set up to utilize the CINRAD/SA radar and GMS satellite, flood-causing heavy rains are pre-warned and forecast with interpretations of the NWP product HLAFS, and a software ofpre-warning operation is finalized to watch this kind of rain over the valley.
基金National Key R&D Program of China(2018YFC1507404)National Natural Science Foundation of China(41805035,41775050,41705035)Guangdong Basic and Applied Basic Research Foundation(2020A1515011034)
文摘A good representation of the interaction between the planetary boundary layer(PBL)and the surface layer(SL)in numerical models is of great importance for the prediction of the initiation and development of convection.This study examined an ensemble that consists of the available suites of PBL and SL parameterizations based on a torrential rainfall event over south China.The sensitivity of the simulations was investigated against objective measurements using multiple PBL and SL parameterization schemes.The main causes of the bias from different parameterization schemes were further analysed by comparing the good and bad ensemble members.The results showed that good members tended to underestimate the rainfall amount but presented a decent evolution of mesoscale convective systems that were responsible for the torrential rainfall.Using the total energy mass flux(TEMF)scheme,the bad members overestimated the amount and spatial coverage of rainfall.The failure of the bad member was due to a spurious convection initiation(CI)resulting from the overestimated high-θe elevated air.The spurious CI developed and expanded rapidly,causing intensive and extensive rainfall over south China.Consistent with previous studies,the TEMF scheme tends to produce a warmer and moister PBL environment.The detailed sensitivity analysis of this case may provide reference for the operational forecast of rainfall over south China using multiple PBL and SL parameterizations.
基金Supported by National Natural Science Foundation of China(41275099,41275012,41205073)
文摘Based on the conventional ground observational data,a numerical simulation and moist potential vorticity( MPV) analysis has been carried on heavy rainfall event over Jiangxi province from 19 June to 20 June 2010,with a meso-scale rainstorm model. The results show that this rare rainstorm is a typical heavy rainfall over Meiyu front. The cold air flow behind North China vortex joined up the southwestern flow located in the northwest part of the strong and stable subtropical high,thus the cold air and warm air converged and maintained over the northern part of Hunan and Jiangxi province. The simulated precipitation of the high resolution model is very similar to the observational rainfall. The model has a good predictive skill for the location,intensity and center of heavy rainfall. By moist potential vorticity analysis,it is found that the distribution characteristic of MPV which heavy rainfall happens ahead has an obvious indication for precipitation forecast. The vertical overlapping of the positive and negative MPV1 areas is favorable to the generation and development of rainstorm. This zone is also the conjoint area of convective instability and baroclinic instability.
文摘The quasi 11-year cycle of sunspot activities and torrential rain days in Fuxin during 1951-2005 were studied.As was shown in the results,the relative number of sunspots and the torrential rain days in the sunspot cycle of trough value were significantly related with a correlation coefficient of 0.842.At the same time,the correlation coefficient between torrential rain days in Fuxin and the relative number of sunspots of certain year within the sunspot cycle of trough value reached 0.737.It was clear that the torrential rain days in Fuxin were closely related with solar activity.The conclusion would provide the favorable climate background and basis for the study of regularity of rainstorm outbreak,monitoring and forecasting of torrential rain and regularity of agricultural drought and flood.
