The oceanic and atmospheric conditions and the related climate impacts of the 2015/16 ENSO cycle were analyzed,based on the latest global climate observational data,especially that of China.The results show that this ...The oceanic and atmospheric conditions and the related climate impacts of the 2015/16 ENSO cycle were analyzed,based on the latest global climate observational data,especially that of China.The results show that this strong El Nino event fully established in spring 2015 and has been rapidly developing into one of the three strongest El Nino episodes in recorded history.Meanwhile,it is also expected to be the longest event recorded,attributable to the stable maintenance of the abnormally warm conditions in the equatorial Pacific Ocean since spring 2014.Owing to the impacts of this strong event,along with climate warming background,the global surface temperature and the surface air temperature over Chinese mainland reached record highs in 2015.Disastrous weather in various places worldwide have occurred in association with this severe El Nino episode,and summer precipitation has reduced significantly in North China,especially over the bend of the Yellow River,central Inner Mongolia,and the coastal areas surrounding Bohai Bay.Serious drought has occurred in some of the above areas.The El Nino episode reached its peak strength during November-December 2015,when a lower-troposphere anomalous anticyclonic circulation prevailed over the Philippines,bringing about abnormal southerlies and substantially increased precipitation in southeastern China.At the same time,a negative phase of the Eurasia-Pacific teleconnection pattern dominated over the mid-high latitudes,which suppressed northerly winds in North China.These two factors together resulted in high concentrations of fine particulate matter（PM2.5） and frequent haze weather in this region.Currently,this strong El Nino is weakening very rapidly,but its impact on climate will continue in the coming months in some regions,especially in China.展开更多
The formation process and characteristics ofcloud physical structure of a severe thunderstorm accompa-nied with strong wind on 23 August, 2001 in Beijing wasstudied using PSU/NCAR mesoscale model ( MM5) couplingwith a...The formation process and characteristics ofcloud physical structure of a severe thunderstorm accompa-nied with strong wind on 23 August, 2001 in Beijing wasstudied using PSU/NCAR mesoscale model ( MM5) couplingwith a severe storm model with hail-bin microphysics. Theresults show that the specific topography and distributionfeatures of cold/warm current in the Beijing region playedprominent roles in forming, developing and maintaining thesevere storm. Due to solar radiation heating and topographiclifting, the convective cells were easily formed when thewesterly airflow passed over high mountainous regions inBeijing. The warm and wet air entered the cloud from itsfrontage and enhanced the convection, and formed a largeamount of graupel/hail particles at the middle and upperportion of the clouds. The precipitation was primarilyformed due to melting of graupel/hail particles. The strongdowndraft was mainly produced by negative buoyancy dueto loading, melting of graupel/hail particles as well asevaporative cooling of rain water. The divergent airflow in-duced by the strong downdraft led to the disastrous burstwinds at the surface and also forced lifting of warm and wetairflow in the moving direction of the storm and formed newclouds that further promoted and maintained the storm de-velopment.展开更多
Most existing distribution networks are difficult to withstand the impact of meteorological disasters. With the development of active distribution networks(ADNs), more and more upgrading and updating resources are app...Most existing distribution networks are difficult to withstand the impact of meteorological disasters. With the development of active distribution networks(ADNs), more and more upgrading and updating resources are applied to enhance the resilience of ADNs. A two-stage stochastic mixed-integer programming(SMIP) model is proposed in this paper to minimize the upgrading and operation cost of ADNs by considering random scenarios referring to different operation scenarios of ADNs caused by disastrous weather events. In the first stage, the planning decision is formulated according to the measures of hardening existing distribution lines, upgrading automatic switches, and deploying energy storage resources. The second stage is to evaluate the operation cost of ADNs by considering the cost of load shedding due to disastrous weather and optimal deployment of energy storage systems(ESSs) under normal weather condition. A novel modeling method is proposed to address the uncertainty of the operation state of distribution lines according to the canonical representation of logical constraints. The progressive hedging algorithm(PHA) is adopted to solve the SMIP model. The IEEE 33-node test system is employed to verify the feasibility and effectiveness of the proposed method. The results show that the proposed model can enhance the resilience of the ADN while ensuring economy.展开更多
Outlined in this paper are main technical specifications of the first profiler developed in China. The profiler is composed of a UHF Doppler radar for wind measurement and a microwave radiometer, and preliminarily app...Outlined in this paper are main technical specifications of the first profiler developed in China. The profiler is composed of a UHF Doppler radar for wind measurement and a microwave radiometer, and preliminarily applied in the Beijing-Tianjin-Hebei base of monitoring disastrous weather in 1989—1990. This paper presents the preliminary and valuable results obtained by the instrument in the monitoring of severe storm generating and evolution, showing the potential of this instrument in weather monitoring.展开更多
Using the data at standard ground observation field of Lingyuan Meteorological Bureau and comparative and parallel observation data during growth period of surrounding Prunus sibirica var suavosperma, and combining so...Using the data at standard ground observation field of Lingyuan Meteorological Bureau and comparative and parallel observation data during growth period of surrounding Prunus sibirica var suavosperma, and combining social investigation data about low-temperature cold injury loss of P. sibirica in recent years, it is found that low-temperature cold injury and abrupt change of temperature in spring are also important factors affecting P. sibirica yield and economic benefit. According to temperature indexes, meteorological department timely issues warning and forecast, and relevant departments and foresters take corresponding preventive measures, and strengthen cultivation technology and management of P. sibinca park. It avoids economic loss of P. sibirica caused by low-temperature cold injury, and obtains high and stable yield.展开更多
Xinjiang, northwest of China, is located in the middle south of Eurasian plate, which collides with the Indian Ocean plate in the south and is pressed southward by the Siberian plate in the north. Therefore, in this r...Xinjiang, northwest of China, is located in the middle south of Eurasian plate, which collides with the Indian Ocean plate in the south and is pressed southward by the Siberian plate in the north. Therefore, in this region there are inland earthquakes with higher frequency and greater magnitude. It is one of the most active areas in China. There were 104 strong earthquakes with magnitude M_s≥6.0 occurring in Xinjiang since 1600展开更多
In this paper, we studied the relationship between environmental factors and disastrousearthquakes of Xinjiang based on the characteristics of time--space distribution of disastrousearthquakes. Through a great deal of...In this paper, we studied the relationship between environmental factors and disastrousearthquakes of Xinjiang based on the characteristics of time--space distribution of disastrousearthquakes. Through a great deal of data handling and several statistic correlation analyses,the method has passed the correlation test on the confidence level of α= 0.01 or 0. 05, whichshows a certain relation between environmental factors and disastrous earthquakes, thus theprediction criterion for disastrous earthquakes with different scales in different time inter-vals is put forward.展开更多
Based on the data of hail,gale,thunderstorm and lightning days in 2 481 stations in China from 1961 to 2016,the spatial and temporal distribution characteristics,periodicity and climate abruption characteristics of fo...Based on the data of hail,gale,thunderstorm and lightning days in 2 481 stations in China from 1961 to 2016,the spatial and temporal distribution characteristics,periodicity and climate abruption characteristics of four kinds of disastrous convective weather in China were analyzed by various mathematical statistics methods. The results showed that in time,the days of four kinds of disastrous convective weather in China decreased,and the hail and thunderstorm days were characterized by " increasing firstly and then decreasing" from 1961 to 2016. The hail,gale,thunderstorm and lightning days in China had oscillation cycles of 3-5,2-3,1-2 and 1-4 a respectively,and the hail and thunderstorm days changed suddenly in 2002 and 1992 respectively. In space,the Qinghai-Tibet Plateau and western Sichuan were the highvalue distribution areas of hail,gale and thunderstorm days. The high-value distribution areas of thunderstorm days were also distributed to the south of the Yangtze River. South China and its southwestern regions at the same latitude were the high-value distribution areas of lightning days. In terms of trend,the hail days in China showed a decreasing trend mainly in the Qinghai-Tibet Plateau. The gale days in China decreased in the east,was unchanged in the central region,and increased and decreased alternately in the west. The thunderstorm days in China increased in Tibet,North China,Chongqing,Zhejiang and northwestern Heilongjiang. The lightning days in China decreased obviously to the south of the Yangtze River. In terms of the fluctuation,the hail days fluctuated greatly in the southeast. The gale days fluctuated greatly to the east of Hu Huanyong line. The thunderstorms days in China fluctuated greatly in the northwest and slightly in the southeast. In addition to the small fluctuation in northern Xinjiang and South China,the lightning days fluctuated greatly in other regions of China.展开更多
Assessment of the disastrous weather warning service benefit has important guidance significance for improving meteorological forecast capability and meteorological service level. Meanwhile, it is also weak link of th...Assessment of the disastrous weather warning service benefit has important guidance significance for improving meteorological forecast capability and meteorological service level. Meanwhile, it is also weak link of the current meteorological work. Took Beibei District of Chongqing as an example, by analyzing issuance of the rainstorm warning signal from 2008 to now, its disastrous weather warning service benefit was evaluated. Result showed that assessment of the disastrous weather warning service benefit should be studied from forecast accuracy, forecast timeliness, forecast coverage and disaster prevention capability.展开更多
[Objective] The research aimed to analyze the disastrous weather of serious drought in Northwest Hunan in summer and autumn of 2009.[Method] According to the meteorological data in Zhangjiajie of Northwest Hunan durin...[Objective] The research aimed to analyze the disastrous weather of serious drought in Northwest Hunan in summer and autumn of 2009.[Method] According to the meteorological data in Zhangjiajie of Northwest Hunan during the drought period from June to September,2009,the disaster characteristics of continuous drought in summer and autumn were analyzed.Based on NCEP/NCAR 2.5°×2.5° reanalysis data,by using the climatic diagnostic method,the formation reason of serious drought was initially analyzed from the circulation characteristics in the middle and high latitudes,Western Pacific subtropical high,the abnormal characteristics of sea surface temperature in the equatorial Middle Eastern Pacific Ocean and the tropical system activity.[Result] The characteristics of serious drought in Northwest Hunan in summer and autumn of 2009 were the quick developed speed,wide influence range,long duration,big disaster loss and long high temperature time.The influence range,duration and harm degree were rare to see in the history.During the arid period(June-September),the atmospheric circulation was abnormal.The polar vortex in the northern hemisphere was weak,and the center was by north.It was two-trough-one-ridge type in the middle and high latitudes of Eurasia.The long-wave trough existed respectively near Balkhash Lake and from Sea of Okhotsk to the east coast in China.The long-wave ridge maintained from Lake Baikal to Central Asia and stabilized in 90°-110° E of Central Asia.From the middle dekad of June to the middle dekad of September,the westerly index increased.The zonal circulation was the main one in the middle and high latitudes of Eurasia.The cold air in the high-latitude frontal zone spread eastward with the small-amplitude fluctuation form along the latitude circle direction,and was difficult to pass the westerly barrier near 45° N to reach the low latitude.Meanwhile,Western Pacific subtropical high jumped northward to control Jiangnan and South China for a long time.The down airflow was prevalent.It was hot an展开更多
Debris flow is an abrupt phenomenon of earth surface movement and typical disaster in mountainous areas with steep terrace, quantity of loose soil and abundant surface runoff. Intense rainfall and rainstorm easily tri...Debris flow is an abrupt phenomenon of earth surface movement and typical disaster in mountainous areas with steep terrace, quantity of loose soil and abundant surface runoff. Intense rainfall and rainstorm easily triggered debris flows and generated huge losses. The disastrous debris flows, on July 4, 2013 at the gullies of Hou, Heilinzi and Xiongjia in Shimian County, Sichuan Province, resulted in 18 casualties and endangering Shimian city with a population of 50,000. These debris flows were characterized by low viscosity with only 0.9% - 1.4% clay soil of less than 0.05mm, density of 1.77 - 1.84 t/m<sup>3</sup>, velocity of 4.4 - 13.5m/s and discharge of 827 - 1248 m<sup>3</sup>/s, respectively, and also delivered sediment of 16.8 × 10<sup>4</sup>m<sup>3</sup>, 12.7 - 13.5 × 10<sup>4</sup> m<sup>3</sup>, 20.5 × 10<sup>4</sup>m<sup>3</sup> out of the outlet, respectively. These three events all generated a hazard chain, which involved in flash flood, channelized debris flow, dammed lake and outburst flood. The threshold conditions of debris flow blocking Nanya River and forming this hazard chain are that the unit width peak discharge and the deposition volume in river channel are more than 37.0 m<sup>3</sup>/s and 4500 m<sup>3</sup>, respectively. These debris flows were initiated by intense rainfall with the antecedent rainfall of over 52 mm and triggering rainstorm of over 36 mm/h. And, the property losses and casualties mainly originated from impacting and scouring, burying and blocking, highway destructing and river channel rising. The irrational location of constructions and the destruction of under-standard prevention constructions were responsible for loss worsening. It was strongly recommended for mitigating that hazards reassessment, integrated control, emergency plan and integrated risk management were made at mountainous urban areas, especially in high-hazard areas.展开更多
Using historical synoptic data, the surface observation data of Guangzhou, the data in the Yearbook on Tropical Cyclones of P. R. China, and NCEP/NCAR reanalysis data of geopotential height, vertical velocity from Jun...Using historical synoptic data, the surface observation data of Guangzhou, the data in the Yearbook on Tropical Cyclones of P. R. China, and NCEP/NCAR reanalysis data of geopotential height, vertical velocity from June to September over the years 1983 to 2004, and defining three days or more in succession with daily maximum temperature over 35°C as a process of high temperature weather, this work analyzes the relationship between the activity of tropical cyclones and the disastrous high temperature weather in Guangzhou. The result shows that disastrous high temperature weather in Guangzhou is closely related to the outer circulation of tropical cyclones, and high temperatures weather over 37°C occur mainly when tropical cyclones move in the range from 400 to 1600 km southeast or east to Guangzhou. Furthermore, rapid temperature increase with descending motion resulting from tropical cyclones is the major factor that induces disastrous high temperature weather in Guangzhou when the city is controlled by the subtropical high.展开更多
Names have been given to tropical cyclones which raging through the western North Pacific Ocean since 1947.However,considering the disastrous impact or some extreme uniqueness quite a few typhoons have their names ret...Names have been given to tropical cyclones which raging through the western North Pacific Ocean since 1947.However,considering the disastrous impact or some extreme uniqueness quite a few typhoons have their names retired from the list.This study conducts preliminary analysis and summarizes the frequency,impact and also explains why they were retired.It shows that a total of 31 typhoons(in the western North Pacific Ocean)have been removed from the list from 1947 on,most of which retired after 2000 amounting to 20 as against 11 before 2000.Collectively,these retired typhoons have made 16843 people killed or missing and caused a heavy property loss of$45.7 billion,averaging 543 fatalities and property loss of$1.69 billion each(capping at 8000 and$10 billion respectively).Most typhoons were retired due to huge personnel and property loss.However,some others were removed for their unique feature such as developed near equator,extremely long typhoon tracks,etc.Moreover,there were some retired due to neither of the above reasons.In this connection,the study also discusses the standard of retiring typhoons.展开更多
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2012CB417205)National Natural Science Foundation of China(41575094)
文摘The oceanic and atmospheric conditions and the related climate impacts of the 2015/16 ENSO cycle were analyzed,based on the latest global climate observational data,especially that of China.The results show that this strong El Nino event fully established in spring 2015 and has been rapidly developing into one of the three strongest El Nino episodes in recorded history.Meanwhile,it is also expected to be the longest event recorded,attributable to the stable maintenance of the abnormally warm conditions in the equatorial Pacific Ocean since spring 2014.Owing to the impacts of this strong event,along with climate warming background,the global surface temperature and the surface air temperature over Chinese mainland reached record highs in 2015.Disastrous weather in various places worldwide have occurred in association with this severe El Nino episode,and summer precipitation has reduced significantly in North China,especially over the bend of the Yellow River,central Inner Mongolia,and the coastal areas surrounding Bohai Bay.Serious drought has occurred in some of the above areas.The El Nino episode reached its peak strength during November-December 2015,when a lower-troposphere anomalous anticyclonic circulation prevailed over the Philippines,bringing about abnormal southerlies and substantially increased precipitation in southeastern China.At the same time,a negative phase of the Eurasia-Pacific teleconnection pattern dominated over the mid-high latitudes,which suppressed northerly winds in North China.These two factors together resulted in high concentrations of fine particulate matter（PM2.5） and frequent haze weather in this region.Currently,this strong El Nino is weakening very rapidly,but its impact on climate will continue in the coming months in some regions,especially in China.
文摘The formation process and characteristics ofcloud physical structure of a severe thunderstorm accompa-nied with strong wind on 23 August, 2001 in Beijing wasstudied using PSU/NCAR mesoscale model ( MM5) couplingwith a severe storm model with hail-bin microphysics. Theresults show that the specific topography and distributionfeatures of cold/warm current in the Beijing region playedprominent roles in forming, developing and maintaining thesevere storm. Due to solar radiation heating and topographiclifting, the convective cells were easily formed when thewesterly airflow passed over high mountainous regions inBeijing. The warm and wet air entered the cloud from itsfrontage and enhanced the convection, and formed a largeamount of graupel/hail particles at the middle and upperportion of the clouds. The precipitation was primarilyformed due to melting of graupel/hail particles. The strongdowndraft was mainly produced by negative buoyancy dueto loading, melting of graupel/hail particles as well asevaporative cooling of rain water. The divergent airflow in-duced by the strong downdraft led to the disastrous burstwinds at the surface and also forced lifting of warm and wetairflow in the moving direction of the storm and formed newclouds that further promoted and maintained the storm de-velopment.
基金supported by National Natural Science Foundation of China (No. U1866603)Innovation Support Program of Chongqing for Preferential Returned Chinese Scholars (No. cx2021036)Natural Science Foundation of Chongqing,China (No. CSTB2022NSCQ-BHX0729)。
文摘Most existing distribution networks are difficult to withstand the impact of meteorological disasters. With the development of active distribution networks(ADNs), more and more upgrading and updating resources are applied to enhance the resilience of ADNs. A two-stage stochastic mixed-integer programming(SMIP) model is proposed in this paper to minimize the upgrading and operation cost of ADNs by considering random scenarios referring to different operation scenarios of ADNs caused by disastrous weather events. In the first stage, the planning decision is formulated according to the measures of hardening existing distribution lines, upgrading automatic switches, and deploying energy storage resources. The second stage is to evaluate the operation cost of ADNs by considering the cost of load shedding due to disastrous weather and optimal deployment of energy storage systems(ESSs) under normal weather condition. A novel modeling method is proposed to address the uncertainty of the operation state of distribution lines according to the canonical representation of logical constraints. The progressive hedging algorithm(PHA) is adopted to solve the SMIP model. The IEEE 33-node test system is employed to verify the feasibility and effectiveness of the proposed method. The results show that the proposed model can enhance the resilience of the ADN while ensuring economy.
文摘Outlined in this paper are main technical specifications of the first profiler developed in China. The profiler is composed of a UHF Doppler radar for wind measurement and a microwave radiometer, and preliminarily applied in the Beijing-Tianjin-Hebei base of monitoring disastrous weather in 1989—1990. This paper presents the preliminary and valuable results obtained by the instrument in the monitoring of severe storm generating and evolution, showing the potential of this instrument in weather monitoring.
文摘Using the data at standard ground observation field of Lingyuan Meteorological Bureau and comparative and parallel observation data during growth period of surrounding Prunus sibirica var suavosperma, and combining social investigation data about low-temperature cold injury loss of P. sibirica in recent years, it is found that low-temperature cold injury and abrupt change of temperature in spring are also important factors affecting P. sibirica yield and economic benefit. According to temperature indexes, meteorological department timely issues warning and forecast, and relevant departments and foresters take corresponding preventive measures, and strengthen cultivation technology and management of P. sibinca park. It avoids economic loss of P. sibirica caused by low-temperature cold injury, and obtains high and stable yield.
文摘Xinjiang, northwest of China, is located in the middle south of Eurasian plate, which collides with the Indian Ocean plate in the south and is pressed southward by the Siberian plate in the north. Therefore, in this region there are inland earthquakes with higher frequency and greater magnitude. It is one of the most active areas in China. There were 104 strong earthquakes with magnitude M_s≥6.0 occurring in Xinjiang since 1600
文摘In this paper, we studied the relationship between environmental factors and disastrousearthquakes of Xinjiang based on the characteristics of time--space distribution of disastrousearthquakes. Through a great deal of data handling and several statistic correlation analyses,the method has passed the correlation test on the confidence level of α= 0.01 or 0. 05, whichshows a certain relation between environmental factors and disastrous earthquakes, thus theprediction criterion for disastrous earthquakes with different scales in different time inter-vals is put forward.
基金Supported by National Natural Science Foundation of China (41801064,71790611)Funds for Research of Atmospheric Sciences in Central Asia (CAAS201804)
文摘Based on the data of hail,gale,thunderstorm and lightning days in 2 481 stations in China from 1961 to 2016,the spatial and temporal distribution characteristics,periodicity and climate abruption characteristics of four kinds of disastrous convective weather in China were analyzed by various mathematical statistics methods. The results showed that in time,the days of four kinds of disastrous convective weather in China decreased,and the hail and thunderstorm days were characterized by " increasing firstly and then decreasing" from 1961 to 2016. The hail,gale,thunderstorm and lightning days in China had oscillation cycles of 3-5,2-3,1-2 and 1-4 a respectively,and the hail and thunderstorm days changed suddenly in 2002 and 1992 respectively. In space,the Qinghai-Tibet Plateau and western Sichuan were the highvalue distribution areas of hail,gale and thunderstorm days. The high-value distribution areas of thunderstorm days were also distributed to the south of the Yangtze River. South China and its southwestern regions at the same latitude were the high-value distribution areas of lightning days. In terms of trend,the hail days in China showed a decreasing trend mainly in the Qinghai-Tibet Plateau. The gale days in China decreased in the east,was unchanged in the central region,and increased and decreased alternately in the west. The thunderstorm days in China increased in Tibet,North China,Chongqing,Zhejiang and northwestern Heilongjiang. The lightning days in China decreased obviously to the south of the Yangtze River. In terms of the fluctuation,the hail days fluctuated greatly in the southeast. The gale days fluctuated greatly to the east of Hu Huanyong line. The thunderstorms days in China fluctuated greatly in the northwest and slightly in the southeast. In addition to the small fluctuation in northern Xinjiang and South China,the lightning days fluctuated greatly in other regions of China.
文摘Assessment of the disastrous weather warning service benefit has important guidance significance for improving meteorological forecast capability and meteorological service level. Meanwhile, it is also weak link of the current meteorological work. Took Beibei District of Chongqing as an example, by analyzing issuance of the rainstorm warning signal from 2008 to now, its disastrous weather warning service benefit was evaluated. Result showed that assessment of the disastrous weather warning service benefit should be studied from forecast accuracy, forecast timeliness, forecast coverage and disaster prevention capability.
文摘[Objective] The research aimed to analyze the disastrous weather of serious drought in Northwest Hunan in summer and autumn of 2009.[Method] According to the meteorological data in Zhangjiajie of Northwest Hunan during the drought period from June to September,2009,the disaster characteristics of continuous drought in summer and autumn were analyzed.Based on NCEP/NCAR 2.5°×2.5° reanalysis data,by using the climatic diagnostic method,the formation reason of serious drought was initially analyzed from the circulation characteristics in the middle and high latitudes,Western Pacific subtropical high,the abnormal characteristics of sea surface temperature in the equatorial Middle Eastern Pacific Ocean and the tropical system activity.[Result] The characteristics of serious drought in Northwest Hunan in summer and autumn of 2009 were the quick developed speed,wide influence range,long duration,big disaster loss and long high temperature time.The influence range,duration and harm degree were rare to see in the history.During the arid period(June-September),the atmospheric circulation was abnormal.The polar vortex in the northern hemisphere was weak,and the center was by north.It was two-trough-one-ridge type in the middle and high latitudes of Eurasia.The long-wave trough existed respectively near Balkhash Lake and from Sea of Okhotsk to the east coast in China.The long-wave ridge maintained from Lake Baikal to Central Asia and stabilized in 90°-110° E of Central Asia.From the middle dekad of June to the middle dekad of September,the westerly index increased.The zonal circulation was the main one in the middle and high latitudes of Eurasia.The cold air in the high-latitude frontal zone spread eastward with the small-amplitude fluctuation form along the latitude circle direction,and was difficult to pass the westerly barrier near 45° N to reach the low latitude.Meanwhile,Western Pacific subtropical high jumped northward to control Jiangnan and South China for a long time.The down airflow was prevalent.It was hot an
文摘Debris flow is an abrupt phenomenon of earth surface movement and typical disaster in mountainous areas with steep terrace, quantity of loose soil and abundant surface runoff. Intense rainfall and rainstorm easily triggered debris flows and generated huge losses. The disastrous debris flows, on July 4, 2013 at the gullies of Hou, Heilinzi and Xiongjia in Shimian County, Sichuan Province, resulted in 18 casualties and endangering Shimian city with a population of 50,000. These debris flows were characterized by low viscosity with only 0.9% - 1.4% clay soil of less than 0.05mm, density of 1.77 - 1.84 t/m<sup>3</sup>, velocity of 4.4 - 13.5m/s and discharge of 827 - 1248 m<sup>3</sup>/s, respectively, and also delivered sediment of 16.8 × 10<sup>4</sup>m<sup>3</sup>, 12.7 - 13.5 × 10<sup>4</sup> m<sup>3</sup>, 20.5 × 10<sup>4</sup>m<sup>3</sup> out of the outlet, respectively. These three events all generated a hazard chain, which involved in flash flood, channelized debris flow, dammed lake and outburst flood. The threshold conditions of debris flow blocking Nanya River and forming this hazard chain are that the unit width peak discharge and the deposition volume in river channel are more than 37.0 m<sup>3</sup>/s and 4500 m<sup>3</sup>, respectively. These debris flows were initiated by intense rainfall with the antecedent rainfall of over 52 mm and triggering rainstorm of over 36 mm/h. And, the property losses and casualties mainly originated from impacting and scouring, burying and blocking, highway destructing and river channel rising. The irrational location of constructions and the destruction of under-standard prevention constructions were responsible for loss worsening. It was strongly recommended for mitigating that hazards reassessment, integrated control, emergency plan and integrated risk management were made at mountainous urban areas, especially in high-hazard areas.
基金Promotion and Application of New Generation Operational Framework and System forWeather Forecasting, a project from the "Promotion Plan for Science and Technology in Guangdong Province"
文摘Using historical synoptic data, the surface observation data of Guangzhou, the data in the Yearbook on Tropical Cyclones of P. R. China, and NCEP/NCAR reanalysis data of geopotential height, vertical velocity from June to September over the years 1983 to 2004, and defining three days or more in succession with daily maximum temperature over 35°C as a process of high temperature weather, this work analyzes the relationship between the activity of tropical cyclones and the disastrous high temperature weather in Guangzhou. The result shows that disastrous high temperature weather in Guangzhou is closely related to the outer circulation of tropical cyclones, and high temperatures weather over 37°C occur mainly when tropical cyclones move in the range from 400 to 1600 km southeast or east to Guangzhou. Furthermore, rapid temperature increase with descending motion resulting from tropical cyclones is the major factor that induces disastrous high temperature weather in Guangzhou when the city is controlled by the subtropical high.
文摘Names have been given to tropical cyclones which raging through the western North Pacific Ocean since 1947.However,considering the disastrous impact or some extreme uniqueness quite a few typhoons have their names retired from the list.This study conducts preliminary analysis and summarizes the frequency,impact and also explains why they were retired.It shows that a total of 31 typhoons(in the western North Pacific Ocean)have been removed from the list from 1947 on,most of which retired after 2000 amounting to 20 as against 11 before 2000.Collectively,these retired typhoons have made 16843 people killed or missing and caused a heavy property loss of$45.7 billion,averaging 543 fatalities and property loss of$1.69 billion each(capping at 8000 and$10 billion respectively).Most typhoons were retired due to huge personnel and property loss.However,some others were removed for their unique feature such as developed near equator,extremely long typhoon tracks,etc.Moreover,there were some retired due to neither of the above reasons.In this connection,the study also discusses the standard of retiring typhoons.
