Based on meteorological data of Zhumadian City in the past 56 years, the damage of flood-causing rainstorm to towns in Zhumadian City as well as its cataclysm form, influencing system, cataclysm characteristics and ac...Based on meteorological data of Zhumadian City in the past 56 years, the damage of flood-causing rainstorm to towns in Zhumadian City as well as its cataclysm form, influencing system, cataclysm characteristics and action mechanism were analyzed to discuss the characteristics and rules of damage caused by flood-causing rainstorm. Meanwhile, countermeasures against flood-causing rainstorm cataclysm in Zhumadian City were proposed to provide scientific references for early warning and monitoring of flood-causing rainstorm as well as flood control and disaster mitigation.展开更多
Based on the daily precipitation data of nine stations representing the Xijiang River valley and the National Center for Environmental Prediction/National Center for Atmospheric Research (USA) reanalysis data, this st...Based on the daily precipitation data of nine stations representing the Xijiang River valley and the National Center for Environmental Prediction/National Center for Atmospheric Research (USA) reanalysis data, this study uses the wavelet analysis and band-pass filter methods to investigate the atmospheric intraseasonal oscillation characteristics of flood-causing rainstorms in the valley during the annually first raining seasons in 1968, 1994, 1998, 2002 and 2005. Results show that the daily precipitation in the valley exhibits significant quasi-biweekly (10 to 20 days) oscillations. The flood-causing rainstorms in the valley were mainly associated with the confluence of low-frequency warm and humid airflow in the lower latitudes and cold and dry airflow in the higher latitudes. The low-frequency vortexes were propagating or in control when this type of rainstorms took place over the valley, being favorable for the convergence of moisture at lower levels and thus vital to the formation of the rainstorms.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
In the early hours of August 18 in 2022,a mountain flood disaster occurred in Datong Hui and Tu Autonomous County,Xining City,Qinghai Province,resulting in 31 deaths.This typical incident of multiple casualties result...In the early hours of August 18 in 2022,a mountain flood disaster occurred in Datong Hui and Tu Autonomous County,Xining City,Qinghai Province,resulting in 31 deaths.This typical incident of multiple casualties resulting from a mountain flood disaster caused by heavy precipitation.In this paper,the mountain flood disaster was analyzed from three aspects,the distribution of the observation station network,assessment of minute-level precipitation,and quantitative precipitation estimated by Xining radar data during August 17-18,2022.It aims to identify the critical gap in comprehensive monitoring systems,and explore effective monitoring methods and estimation algorithms of minute-level quantitative precipitation.Moreover,subsequent defense countermeasures were proposed.These findings offer significant guidance for enhancing meteorological disaster prevention capabilities,strengthening the first line of defense in disaster prevention and mitigation,and supporting evidence-based decision-making for local governments and flood control departments.展开更多
Based on the data of daily precipitation in 11 national ground meteorological observation stations in Jining City from 1981 to 2020,the interdecadal variation,intensity,range and spatial distribution of rainstorms in ...Based on the data of daily precipitation in 11 national ground meteorological observation stations in Jining City from 1981 to 2020,the interdecadal variation,intensity,range and spatial distribution of rainstorms in Jining City were analyzed.The results show that the number of rainstorm days and the total amount of rainstorms in Jining City had significant changes among different decades.There was a continuous upward trend from the 1980s to the early 21 st century and a decrease after the early 21 st century.Rainstorms had distinct seasonal characteristics.They were mainly concentrated in summer,especially in July and August.In terms of spatial distribution,the frequency and intensity of rainstorms in the southeastern regions were significantly higher than those in the northwestern regions.The above results can provide a scientific basis for flood control and disaster reduction in Jining City.展开更多
Based on conventional observation data,NCEP reanalysis data and observation data of automatic stations,a rainstorm weather process occurring in Shaoguan City during December 14-17,2013 was analyzed.The results show th...Based on conventional observation data,NCEP reanalysis data and observation data of automatic stations,a rainstorm weather process occurring in Shaoguan City during December 14-17,2013 was analyzed.The results show that the main causes of the winter rainstorm in Shaoguan City were the strong southwest airflow at 500 and 700 hPa,high humidity,the influence of a low-pressure trough at 850 hPa,and the southward movement of cold air on the ground.展开更多
An extraordinary tropical cyclone-remote rainstorm with a 24-hour precipitation amount of 624.1 mm occurred in Zhengzhou,China,on 20 July 2021,during which a severe hourly precipitation amount of 201.9 mm at 1700 LST(...An extraordinary tropical cyclone-remote rainstorm with a 24-hour precipitation amount of 624.1 mm occurred in Zhengzhou,China,on 20 July 2021,during which a severe hourly precipitation amount of 201.9 mm at 1700 LST(LST=UTC+8)caused significant economic losses and casualties.Observational analysis and backward trajectory modeling showed that low-level water vapor for this extraordinary rainstorm was transported by the southeasterly jet below 900 hPa from the intensifying Typhoon In-Fa(2021)in the western North Pacific(low-level southeasterly channel).Although the southerly flow between 900 and 800 hPa brought water vapor from the developing Typhoon Cempaka in the South China Sea(low-level southerly channel),it did not converge over Zhengzhou.展开更多
A record-breaking prolonged and extreme rainstorm occurred in Henan province,China during 18–23 July 2021.Global and regional numerical weather prediction(NWP)models consistently underpredicted both the 24-h accumula...A record-breaking prolonged and extreme rainstorm occurred in Henan province,China during 18–23 July 2021.Global and regional numerical weather prediction(NWP)models consistently underpredicted both the 24-h accumulated rainfall amount and the 1-h extreme precipitation in Zhengzhou city.This study examines the potential impacts of data assimilation(DA)of atmospheric vertical profiles based on the train-based mobile observation(MO)platforms on precipitation forecasts.The research involved assimilating virtual train-based air temperature(Ta),relative humidity(RH),U and V components of wind profile data based on the ERA5 reanalysis datasets into the Weather Research and Forecasting(WRF)model using three-dimensional variational(3DVar)method.Analysis confirms the reliability of Ta,RH,and wind speed(WS)profiles from ERA5 reanalysis datasets.The assimilation of virtual train-based moisture profiles enhanced the RH analysis field.Furthermore,the forecasts more accurately represented the coverage and intensity of the 6-hour and 24-hour accumulated precipitation,as well as areas with maximum rainfall durations exceeding 20 hours.The threat score(TS)and bias metrics for 6-h,12-h and 24-h accumulated precipitation forecasts showed marked improvement for heavy to torrential rain in Henan province,particularly in the Central and Northern regions(hereinafter referred to region CNH).The TS for 24-h accumulated precipitation forecasts at 50 and 100 mm rainfall levels increased by 0.17 and 0.18 in Henan province,and by 0.13 and 0.18 in region CNH.During the rainstorm period,water vapor content increased substantially,with enhanced moisture transport from south of Henan province to region CNH driven by southwesterly winds,accompanied by significantly strengthened updrafts.These improvement in water vapor and upward motion ultimately enhanced the forecasts of this extreme rainstorm event.展开更多
Starting from the Bay of Bengal storm,based on conventional meteorological data,FY2G meteorological satellite data,EC fine grid data and ERA5 reanalysis data,the first rainstorm process in Dehong Prefecture in the ear...Starting from the Bay of Bengal storm,based on conventional meteorological data,FY2G meteorological satellite data,EC fine grid data and ERA5 reanalysis data,the first rainstorm process in Dehong Prefecture in the early summer of 2024 was analyzed.The results show that the strengthening and northeastward movement of the Bay of Bengal storm"Remal"was the main influencing system for the generation of continuous heavy precipitation in Dehong Prefecture from May 25 to 27,2024.The establishment and strengthening of the low-level southwest jet stream provided better dynamic,water vapor and energy conditions for the generation of this heavy precipitation.The generation and maintenance of rainstorm required the transportation of a steady stream of water vapor to the rainstorm area,and there was strong convergence of water vapor in the rainstorm area.Therefore,in the forecast of summer rainstorm,whether the low-level jet stream is generated or not is very important for the forecast of rainstorm.In addition,there was a good corresponding relationship between the falling area of heavy precipitation,precipitation intensity and duration,and low-level water vapor convergence area.The establishment of southwest monsoon is of great significance to the beginning date of rainy season in Dehong Prefecture.The beginning date of rainy season in Dehong Prefecture was closely related to the first rainstorm process in Dehong Prefecture in early summer.In the future prediction of the beginning date of rainy season in Dehong Prefecture,the first statewide rainstorm process in early summer should be the key point for the prediction.展开更多
According to the daily precipitation data in Beijing area from 1985 to 2008,rainstorm weather index （10.4-38.8 mm） and climate index （daily precipitation ≥27.5 mm） in Beijing area were obtained by using the deter...According to the daily precipitation data in Beijing area from 1985 to 2008,rainstorm weather index （10.4-38.8 mm） and climate index （daily precipitation ≥27.5 mm） in Beijing area were obtained by using the determination method of extreme climate event index recommended by IPCC. Based on rainstorm weather index,rainstorm climate index and national rainstorm standard,the number of rainstorm days and rainfall amount in past years were calculated,and the correlation of annual number of rainy days,rainstorm days,precipitation and rainstorm amount with the flood disaster ratio of crop was analyzed,and the results showed that annual number of rainy days and rainstorm days couldn＇t reflect flood disaster ratio of crop truly,while annual precipitation and rainstorm amount had obvious linear positive correlation with the flood disaster ratio of crop. In addition,the correlation degree between rainstorm amount calculated by regional climate index and flood disaster ratio of crop was the highest,so it was suggested that rainstorm amount calculated by regional rainstorm climate index could be used to predict and evaluate flood disaster.展开更多
A rare local rainstorm weather in the midsummer rainy weather process appeared in the northwest of Hubei Province during July 8-13,2009.The circulation situation,the contributions of dynamic,thermal force and water va...A rare local rainstorm weather in the midsummer rainy weather process appeared in the northwest of Hubei Province during July 8-13,2009.The circulation situation,the contributions of dynamic,thermal force and water vapor to this strong precipitation in this process were discussed.The results showed that the cold air which was brought by Lake Balkis cold vortex was the trigger mechanism of local rainstorm,and Lake Baikal low pressure provided the foreign dynamic for the adjustment of East Asia circulation.When the rainstorm occurred,the divergence in the divergence field had the strong 'pumping effect' in the high altitude.The warm wet airflow in the Bay of Bengal and the South China Sea was the water vapor source of rainstorm.The falling zone of rainstorm appeared in the front of energy frontal zone,and the axis line in the top of high-energy tongue deviated to the side of cold air.Q vector divergence and the negative value zone of water vapor helicity had the important indication effect for the short-term forecast of local rainstorm.展开更多
By using observation data,numerical forecast product and non-conventional observation data,the process of a rainstorm happened on July 15th,2008 was analyzed. The evolution process of situation field and the predictio...By using observation data,numerical forecast product and non-conventional observation data,the process of a rainstorm happened on July 15th,2008 was analyzed. The evolution process of situation field and the prediction error by numerical forecast products were mainly analyzed. Some local indices for forecasting rainstorm were obtained,so as to guide rainstorm prediction in the future.展开更多
[Objective] One regional rainstorm weather in the south area of Shaanxi was expounded.[Method] By employing the NCEP/NCAR 1°×1°reanalysis data,routine observation and automatic precipitation station dat...[Objective] One regional rainstorm weather in the south area of Shaanxi was expounded.[Method] By employing the NCEP/NCAR 1°×1°reanalysis data,routine observation and automatic precipitation station data,the large scale circulation background field of regional precipitation in the south area of Shaanxi province from July 16-18 in 2010 was expounded.By dint of physical quantity such as the meridional wind,relative humidity and false relative temperature,the characteristics of dry intrusion and its role in rainstorm were expounded.[Result] The mild and high latitude at 500 hPa was stable.The continental high pressure and subtropical high pressure were stable.The 700 and 850 hPa shear lines or low vortexes were the main influence system that resulted into large scale of rainstorm in south Shaanxi.The landing typhoon had distinct influences on the importance of storm.The influence of typhoon and subtropical high was mutual.It not only formed and strengthened the torrent in the low air,also transmitted water vapor and energy incessantly to the south area of Shaanxi,playing an important role in augment of rainstorm.There were two distinct dry intrusions in the rainstorm process,showing a dense dry layer in the high layer of convective layer.The existence of dry layer was conductive to the accumulation of convective unstable energy in the low layer.The release of convective unstable energy could transmit warm and wet airstream in the low level to the higher level,being conductive to the occurrence of precipitation.The analysis of θse in the warp direction vertical profile suggested that there was frontal zone in this rainstorm process and the dry air activity in this rainstorm process was very strong.[Conclusion] The study provided theoretical reference to the forecast in future.展开更多
文摘Based on meteorological data of Zhumadian City in the past 56 years, the damage of flood-causing rainstorm to towns in Zhumadian City as well as its cataclysm form, influencing system, cataclysm characteristics and action mechanism were analyzed to discuss the characteristics and rules of damage caused by flood-causing rainstorm. Meanwhile, countermeasures against flood-causing rainstorm cataclysm in Zhumadian City were proposed to provide scientific references for early warning and monitoring of flood-causing rainstorm as well as flood control and disaster mitigation.
基金Project of Science and Technology Program of Guangdong (2006B37202004)Key project of Science and Technology Program of Guangzhou (2007Z1-E0101)+2 种基金Project of Science and Technology Programof Guangdong (2009A030302012)Specialized Project for Forecasters of Promotion of New Technology of China Meteorological Administration (CMATG2007Y04)Project of Guangdong Meteorlogical Bureau(2008A02)
文摘Based on the daily precipitation data of nine stations representing the Xijiang River valley and the National Center for Environmental Prediction/National Center for Atmospheric Research (USA) reanalysis data, this study uses the wavelet analysis and band-pass filter methods to investigate the atmospheric intraseasonal oscillation characteristics of flood-causing rainstorms in the valley during the annually first raining seasons in 1968, 1994, 1998, 2002 and 2005. Results show that the daily precipitation in the valley exhibits significant quasi-biweekly (10 to 20 days) oscillations. The flood-causing rainstorms in the valley were mainly associated with the confluence of low-frequency warm and humid airflow in the lower latitudes and cold and dry airflow in the higher latitudes. The low-frequency vortexes were propagating or in control when this type of rainstorms took place over the valley, being favorable for the convergence of moisture at lower levels and thus vital to the formation of the rainstorms.
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the Key Research and Development and Transformation Plan Project of Science and Technology Department of Qinghai Province in 2023(2023-SF-111).
文摘In the early hours of August 18 in 2022,a mountain flood disaster occurred in Datong Hui and Tu Autonomous County,Xining City,Qinghai Province,resulting in 31 deaths.This typical incident of multiple casualties resulting from a mountain flood disaster caused by heavy precipitation.In this paper,the mountain flood disaster was analyzed from three aspects,the distribution of the observation station network,assessment of minute-level precipitation,and quantitative precipitation estimated by Xining radar data during August 17-18,2022.It aims to identify the critical gap in comprehensive monitoring systems,and explore effective monitoring methods and estimation algorithms of minute-level quantitative precipitation.Moreover,subsequent defense countermeasures were proposed.These findings offer significant guidance for enhancing meteorological disaster prevention capabilities,strengthening the first line of defense in disaster prevention and mitigation,and supporting evidence-based decision-making for local governments and flood control departments.
基金the Project of Jining Meteorological Bureau(2023JNZL09).
文摘Based on the data of daily precipitation in 11 national ground meteorological observation stations in Jining City from 1981 to 2020,the interdecadal variation,intensity,range and spatial distribution of rainstorms in Jining City were analyzed.The results show that the number of rainstorm days and the total amount of rainstorms in Jining City had significant changes among different decades.There was a continuous upward trend from the 1980s to the early 21 st century and a decrease after the early 21 st century.Rainstorms had distinct seasonal characteristics.They were mainly concentrated in summer,especially in July and August.In terms of spatial distribution,the frequency and intensity of rainstorms in the southeastern regions were significantly higher than those in the northwestern regions.The above results can provide a scientific basis for flood control and disaster reduction in Jining City.
文摘Based on conventional observation data,NCEP reanalysis data and observation data of automatic stations,a rainstorm weather process occurring in Shaoguan City during December 14-17,2013 was analyzed.The results show that the main causes of the winter rainstorm in Shaoguan City were the strong southwest airflow at 500 and 700 hPa,high humidity,the influence of a low-pressure trough at 850 hPa,and the southward movement of cold air on the ground.
基金supported by the National Natural Science Foundation of China(Grant No.42305007).
文摘An extraordinary tropical cyclone-remote rainstorm with a 24-hour precipitation amount of 624.1 mm occurred in Zhengzhou,China,on 20 July 2021,during which a severe hourly precipitation amount of 201.9 mm at 1700 LST(LST=UTC+8)caused significant economic losses and casualties.Observational analysis and backward trajectory modeling showed that low-level water vapor for this extraordinary rainstorm was transported by the southeasterly jet below 900 hPa from the intensifying Typhoon In-Fa(2021)in the western North Pacific(low-level southeasterly channel).Although the southerly flow between 900 and 800 hPa brought water vapor from the developing Typhoon Cempaka in the South China Sea(low-level southerly channel),it did not converge over Zhengzhou.
基金R&D major projects from China State Railway Group Co.,Ltd.(K2022G039)Tibet Autonomous Region Science and Technology Program Project(XZ202402ZD0006-06)+1 种基金Open bidding project for selecting the best candidates from China Meteorological Administration(CMAJBGS202303)The Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK0105)。
文摘A record-breaking prolonged and extreme rainstorm occurred in Henan province,China during 18–23 July 2021.Global and regional numerical weather prediction(NWP)models consistently underpredicted both the 24-h accumulated rainfall amount and the 1-h extreme precipitation in Zhengzhou city.This study examines the potential impacts of data assimilation(DA)of atmospheric vertical profiles based on the train-based mobile observation(MO)platforms on precipitation forecasts.The research involved assimilating virtual train-based air temperature(Ta),relative humidity(RH),U and V components of wind profile data based on the ERA5 reanalysis datasets into the Weather Research and Forecasting(WRF)model using three-dimensional variational(3DVar)method.Analysis confirms the reliability of Ta,RH,and wind speed(WS)profiles from ERA5 reanalysis datasets.The assimilation of virtual train-based moisture profiles enhanced the RH analysis field.Furthermore,the forecasts more accurately represented the coverage and intensity of the 6-hour and 24-hour accumulated precipitation,as well as areas with maximum rainfall durations exceeding 20 hours.The threat score(TS)and bias metrics for 6-h,12-h and 24-h accumulated precipitation forecasts showed marked improvement for heavy to torrential rain in Henan province,particularly in the Central and Northern regions(hereinafter referred to region CNH).The TS for 24-h accumulated precipitation forecasts at 50 and 100 mm rainfall levels increased by 0.17 and 0.18 in Henan province,and by 0.13 and 0.18 in region CNH.During the rainstorm period,water vapor content increased substantially,with enhanced moisture transport from south of Henan province to region CNH driven by southwesterly winds,accompanied by significantly strengthened updrafts.These improvement in water vapor and upward motion ultimately enhanced the forecasts of this extreme rainstorm event.
基金Supported by the"Short,Simple and Fast"Project of Meteorological Science and Technology of Dehong Prefecture(DPK2024-01).
文摘Starting from the Bay of Bengal storm,based on conventional meteorological data,FY2G meteorological satellite data,EC fine grid data and ERA5 reanalysis data,the first rainstorm process in Dehong Prefecture in the early summer of 2024 was analyzed.The results show that the strengthening and northeastward movement of the Bay of Bengal storm"Remal"was the main influencing system for the generation of continuous heavy precipitation in Dehong Prefecture from May 25 to 27,2024.The establishment and strengthening of the low-level southwest jet stream provided better dynamic,water vapor and energy conditions for the generation of this heavy precipitation.The generation and maintenance of rainstorm required the transportation of a steady stream of water vapor to the rainstorm area,and there was strong convergence of water vapor in the rainstorm area.Therefore,in the forecast of summer rainstorm,whether the low-level jet stream is generated or not is very important for the forecast of rainstorm.In addition,there was a good corresponding relationship between the falling area of heavy precipitation,precipitation intensity and duration,and low-level water vapor convergence area.The establishment of southwest monsoon is of great significance to the beginning date of rainy season in Dehong Prefecture.The beginning date of rainy season in Dehong Prefecture was closely related to the first rainstorm process in Dehong Prefecture in early summer.In the future prediction of the beginning date of rainy season in Dehong Prefecture,the first statewide rainstorm process in early summer should be the key point for the prediction.
基金Supported by Cultivation Fund for Scientific and Technical innovation Project of Higher Education of Ministry of Education of China(708013)National Key Technology R &D Program in the 11th Five Year Plan of China (2008BAK50B02, 2007BAC29B05)~~
文摘According to the daily precipitation data in Beijing area from 1985 to 2008,rainstorm weather index （10.4-38.8 mm） and climate index （daily precipitation ≥27.5 mm） in Beijing area were obtained by using the determination method of extreme climate event index recommended by IPCC. Based on rainstorm weather index,rainstorm climate index and national rainstorm standard,the number of rainstorm days and rainfall amount in past years were calculated,and the correlation of annual number of rainy days,rainstorm days,precipitation and rainstorm amount with the flood disaster ratio of crop was analyzed,and the results showed that annual number of rainy days and rainstorm days couldn＇t reflect flood disaster ratio of crop truly,while annual precipitation and rainstorm amount had obvious linear positive correlation with the flood disaster ratio of crop. In addition,the correlation degree between rainstorm amount calculated by regional climate index and flood disaster ratio of crop was the highest,so it was suggested that rainstorm amount calculated by regional rainstorm climate index could be used to predict and evaluate flood disaster.
基金Supported by The Special Project of National Public Welfare Industry(Meteorology)(GYHY200806002)The Key Project of Science and Technology Development Fund of Wuhan Regional Meteorological Center of China Meteorological Administration(QY-Z-200801)
文摘A rare local rainstorm weather in the midsummer rainy weather process appeared in the northwest of Hubei Province during July 8-13,2009.The circulation situation,the contributions of dynamic,thermal force and water vapor to this strong precipitation in this process were discussed.The results showed that the cold air which was brought by Lake Balkis cold vortex was the trigger mechanism of local rainstorm,and Lake Baikal low pressure provided the foreign dynamic for the adjustment of East Asia circulation.When the rainstorm occurred,the divergence in the divergence field had the strong 'pumping effect' in the high altitude.The warm wet airflow in the Bay of Bengal and the South China Sea was the water vapor source of rainstorm.The falling zone of rainstorm appeared in the front of energy frontal zone,and the axis line in the top of high-energy tongue deviated to the side of cold air.Q vector divergence and the negative value zone of water vapor helicity had the important indication effect for the short-term forecast of local rainstorm.
文摘By using observation data,numerical forecast product and non-conventional observation data,the process of a rainstorm happened on July 15th,2008 was analyzed. The evolution process of situation field and the prediction error by numerical forecast products were mainly analyzed. Some local indices for forecasting rainstorm were obtained,so as to guide rainstorm prediction in the future.
文摘[Objective] One regional rainstorm weather in the south area of Shaanxi was expounded.[Method] By employing the NCEP/NCAR 1°×1°reanalysis data,routine observation and automatic precipitation station data,the large scale circulation background field of regional precipitation in the south area of Shaanxi province from July 16-18 in 2010 was expounded.By dint of physical quantity such as the meridional wind,relative humidity and false relative temperature,the characteristics of dry intrusion and its role in rainstorm were expounded.[Result] The mild and high latitude at 500 hPa was stable.The continental high pressure and subtropical high pressure were stable.The 700 and 850 hPa shear lines or low vortexes were the main influence system that resulted into large scale of rainstorm in south Shaanxi.The landing typhoon had distinct influences on the importance of storm.The influence of typhoon and subtropical high was mutual.It not only formed and strengthened the torrent in the low air,also transmitted water vapor and energy incessantly to the south area of Shaanxi,playing an important role in augment of rainstorm.There were two distinct dry intrusions in the rainstorm process,showing a dense dry layer in the high layer of convective layer.The existence of dry layer was conductive to the accumulation of convective unstable energy in the low layer.The release of convective unstable energy could transmit warm and wet airstream in the low level to the higher level,being conductive to the occurrence of precipitation.The analysis of θse in the warp direction vertical profile suggested that there was frontal zone in this rainstorm process and the dry air activity in this rainstorm process was very strong.[Conclusion] The study provided theoretical reference to the forecast in future.
