Continuous rainy and cold weather in Yiwu in early spring of 2009 was analyzed.The results showed that the continuous rainy and cold weather occurred after temperature increased in early days.It is mainly because that...Continuous rainy and cold weather in Yiwu in early spring of 2009 was analyzed.The results showed that the continuous rainy and cold weather occurred after temperature increased in early days.It is mainly because that the high geopotential height near Ural Mountains lasted for a long time,while the geopotential height was abnormally low in the east of central Asia.Meanwhile,the low-pressure trough in the south of Qinghai- Tibet Plateau was very active and moved towards the east frequently,and subtropical high was strong.Compared with continuous rainy and cold weather in early 2008,during the process of this continuous rainy and cold weather in 2009,the decrease in sea surface temperature of the middle and eastern Pacific Ocean near the equator was weaker;the blocking high pressure was slightly weaker,and the low pressure over Mongolia was strong;subtropical high was stronger and showed zonal distribution;south trough was slightly weaker.Compared with the previous continuous rainy and cold weather,the duration of this continuous rainy and cold weather in 2009 was not the longest,and its sunshine hours were not the least,but its temperature was higher,which might result from obvious increase of temperature in the early days.The research could provide scientific references for the prediction of continuous rainy and cold weather in future.展开更多
Reflection of stratospheric planetary waves and its impact on tropospheric cold weather over Asia during January 2008 were investigated by applying two dimensional Eliassen–Palm(EP) flux and three-dimensional Plumb w...Reflection of stratospheric planetary waves and its impact on tropospheric cold weather over Asia during January 2008 were investigated by applying two dimensional Eliassen–Palm(EP) flux and three-dimensional Plumb wave activity fluxes. The planetary wave propagation can clearly be seen in the longitude–height and latitude–height sections of the Plumb wave activity flux and EP flux, respectively, when the stratospheric basic state is partially reflective. Primarily, a wave packet emanating from Baffin Island/coast of Labrador propagated eastward, equatorward and was reflected over Central Eurasia and parts of China, which in turn triggered the advection of cold wind from the northern part of the boreal forest regions and Siberia to the subtropics. The wide region of Central Eurasia and China experienced extreme cold weather during the second ten days of January 2008, whereas the extraordinary persistence of the event might have occurred due to an anomalous blocking high in the Urals–Siberia region.展开更多
Based on the conventional high-and low-altitude and surface observation data,the weather analysis and diagnosis methods were applied to analyze the cold wave process of Ulanqab in January 2016 from the aspects of weat...Based on the conventional high-and low-altitude and surface observation data,the weather analysis and diagnosis methods were applied to analyze the cold wave process of Ulanqab in January 2016 from the aspects of weather reality,circulation background,weather causes,and forecast test.The results show that strong cold air accumulated gradually near Lake Baikal and Central Siberia,affecting the city in a northwest path.During the cold wave process,the transverse trough moved southwards slowly at 500 hPa,and the ground cold high pressure was strong and stable.The cold air continued to move southwards,resulting in the strong cold wave and gale weather with a large impact range and long duration.The high-altitude jet at 300 hPa strengthened the cold wave pile,which was conducive to the outbreak of the cold wave.The intensity and location changes of the 500 hPa positive vorticity center,850 hPa cold advection region and 24-h ground pressure variation well showed the intensity of the cold wave process and the variation of the affected region.The influence of strong cold advection,ground positive pressure variation,and strong vertical wind shear were the main reasons for a strong drop in temperature and gale weather in this process.The test results of prediction reveal that the forecast value of the maximum temperature were relatively lower than the actual value,while the forecast of the minimum temperature was more accurate.The three warning signals were issued timely and accurately.The circulation pattern predicted by numerical models was more accurate in the early stage of the process,but there was an error in the late stage,and the forecast system moved slower than the actual situation.展开更多
Considering the differences between the Northeast China Cold Vortex(CV) and the Mid-Summer(MS) rainy period and their corresponding atmospheric circulations are comprehensively analyzed, and the objective identificati...Considering the differences between the Northeast China Cold Vortex(CV) and the Mid-Summer(MS) rainy period and their corresponding atmospheric circulations are comprehensively analyzed, and the objective identification methods of defining the annual beginning and ending dates of Northeast China CV and MS rainy periods are developed respectively.The annual beginning date of the CV(MS) rainy period is as follows. In a period from April to August, if daily regional mean precipitation ryi is larger than yearly regional mean precipitation R(or 2R) on a certain day, the station precipitation rs is larger than the station yearly mean precipitation r(or 2 r) in at least 50% of stations in Northeast China, and this condition is satisfied in the following 2(7) days, then this date is defined as the beginning date of the CV(MS) rainy period.While the definition of the ending date of the MS rainy period shows the opposite process to its beginning date. With this objective identification method, the multi-year average(1981–2010) beginning date of the CV rainy period is May 3, the beginning date of the MS rainy period is June 27, the ending day of the CV rainy period is defined as the day before the beginning date of the MS rainy period, and the ending date of the MS rainy period is August 29. Meanwhile, corresponding anomaly analysis at a 500-h Pa geopotential height, 850-h Pa wind, Omega and relative humidity fields all show that the definitions of the average beginning and ending dates of the CV and MS rainy periods have a certain circulation meaning.Furthermore, the daily evolution of the CV index, meridional and zonal wind index, etc. all show that these objectively defined beginning and ending dates of the CV and MS rainy periods have climate significance.展开更多
The article is devoted to a discussion of the possibilities of biometeorological assessment of the severity of weather conditions during the cold season.The relevance of the study is ensured not only by the fact that ...The article is devoted to a discussion of the possibilities of biometeorological assessment of the severity of weather conditions during the cold season.The relevance of the study is ensured not only by the fact that residents of a number of states,whose total number is more than 27 million people,live in these extreme climatic conditions,but also by the need to improve biometeorological approaches to assessing the impact of these conditions on the body and health of the population.This study examined biometeorological characteristics that illustrate a measure of cold stress.These include the Siple wind-chill index;Bodman winter severity index;Arnoldi weather hardness coefficient;Mountain wind chill index;weather hardness coefficient according to I.M.Osokin.The results of a comparison of winter severity assessments based on the values of the calculated Siple and Bodman indices made it possible to establish that the Bodman index is more acceptable when assessing mildly severe winters.The most adequate for assessing the“severity”of the cold period against the background of a decrease in air temperature and an increase in wind speed is the Siple index.The need to provide the countries of the world with high-quality hydrometeorological and biometeorological forecast information is justified and relevant.In this regard,these studies are very promising.展开更多
[Objective] The research aimed to study the variation characteristics of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years.[Method] Based on the daily average temperature data...[Objective] The research aimed to study the variation characteristics of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years.[Method] Based on the daily average temperature data from 1961 to 2010 at 88 meteorological stations in Guangxi,yearly days and end date of low temperature and rainy weather during spring sowing period were carried out statistics.The variation characteristics of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years were analyzed by using linear tendency calculation,phased analysis,Morlet wavelet analysis and correlation analysis.Moreover,the influences of climate warming on days and end date of low temperature and rainy weather in spring sowing period were analyzed.[Result] The average days of low temperature and rainy weather in Guangxi during spring sowing period from 1961 to 2010 was during 3.5-23.2 d.The regional distribution characteristics were that it was more in northeast and mountain zone,and less in southwest and valley.The regional distribution characteristics of end date were that it was late in northeast and mountain zone,and early in southwest and valley.The days of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years presented slight decrease trend,and the end date presented slight advancing trend.The phased variation characteristics of days and end date of low temperature and rainy weather were obvious.The days of low temperature and rainy weather from the early 1980s to metaphase of 1990s was obviously more,and the end date was obviously later.After the 1990s,the days of low temperature and rainy weather was obviously less,and the end date was obviously earlier.The days of low temperature and rainy weather had periodic oscillation signals of 4,6,8,10-14 years.The end date had periodic oscillation signals of 6,12-14 years.The days and end date of low temperature and rainy weather in Guangxi during spring sowing period significantly related to average temperature from middle dekad of February to first dekad of April.The climate warming made that the days of low temperature and rainy weather tended to decrease,and the end date tended to advance.[Conclusion] The research provided reference for further understanding the occurrence rule of low temperature and rainy weather,going after profits and avoiding disadvantages,reasonably arranging production,carrying out correlated research.展开更多
Objective:To investigate the effect of cold weather on carotid artery stenosis and occlusion.Methods:We conducted a retrospective observational study,in which 145 patients with carotid artery stenosis and occlusion we...Objective:To investigate the effect of cold weather on carotid artery stenosis and occlusion.Methods:We conducted a retrospective observational study,in which 145 patients with carotid artery stenosis and occlusion were enrolled[115 men and 30 women;the mean age was 61.08 years(95%CI 59.27-62.88)].Patients were divided into the low-temperature group(n=98)(≤12℃)and the non-low temperature group(n=47)(>12℃).Clinical characteristics,blood pressure,National Institutes of Health Stroke Scale(NIHSS),blood fat,and blood viscositys were compared between the two groups.Correlation between NIHSS and mean daily temperature was analyzed.Results:There was no significant difference in the systolic and diastolic blood pressure between the two groups(P>0.05).The NIHSS score was slightly higher in the non-low temperature group compared to that of the low-temperature group(U=2984,P<0.01).Glycemia,cholesterol level,prothrombin time,fibrinogen,and International Normalized Ratio did not show any significant difference(P>0.05).Correlation analysis showed a very low positive and statistically significant correlation between ambient temperature and NIHSS score(r=0.18,P=0.029).Conclusion:Cold weather does not impact blood pressure,blood cholesterol,and coagulation factors of patients with carotid artery stenosis and occlusion.The neurological deficit is more severe in the non-low ambient temperature group.A potential relationship exists between ambient temperature and the level of neurological impairment.展开更多
Application of weathering and cold-formed steel in transmission lines can reduce steel consumption and environmental pollution. Some advances in the studies on the weathering and cold-formed steel in transmission towe...Application of weathering and cold-formed steel in transmission lines can reduce steel consumption and environmental pollution. Some advances in the studies on the weathering and cold-formed steel in transmission tower are introduced. Firstly, corrosion-resistant tests of weathering steel samples under different simulating technical atmospheres were carried out separately for 240 hours. It shows that the corrosion degree of joint samples is higher than that of single chip samples, and the corrosion-resistant performance of weathering steel is superior to common carbon steel. The corrosion-resistance of weathering steel meets with the requirement of transmission tower. Secondly, experiments and finite element analysis for cold-formed angles and a 220kV prototype tower were completed, and the stability coeffi-cient fitting curves as well as the modification formulas of slenderness ratio for cold-formed members were determined. According to the structural characteristics of transmission towers, four sections of cold-formed angles with different sections and slenderness ratios were selected in this study. The finite element model well predicted the buckling behav-iour of the cold-formed members. Ultimate loads calculating by the fitting curve were well agreed to the experimental values, especially for the members with small slenderness ratios. Weight of the cold-formed steel tower can be reduced by more than 5 percent after considering the strength enhancement. Cost of the weathering and cold-formed steel transmission tower is nearly equivalent to that of hot-rolled steel tower with hot galvanizing.展开更多
China experienced significant flooding in the summer of 2020 and multiple extreme cold surges during the winter of 2020/21.Additionally,the 2020 typhoon season had below average activity with especially quiet activity...China experienced significant flooding in the summer of 2020 and multiple extreme cold surges during the winter of 2020/21.Additionally,the 2020 typhoon season had below average activity with especially quiet activity during the first half of the season in the western North Pacific(WNP).Sea surface temperature changes in the Pacific,Indian,and Atlantic Oceans all contributed to the heavy rainfall in China,but the Atlantic and Indian Oceans seem to have played dominant roles.Enhancement and movement of the Siberian High caused a wavier pattern in the jet stream that allowed cold polar air to reach southward,inducing cold surges in China.Large vertical wind shear and low humidity in the WNP were responsible for fewer typhoons in the first half of the typhoon season.Although it is known that global warming can increase the frequency of extreme weather and climate events,its influences on individual events still need to be quantified.Additionally,the extreme cold surge during 16–18 February 2021 in the United States shares similar mechanisms with the winter 2020/21 extreme cold surges in China.展开更多
The aim of this work is to investigate the influence of rainy weather on traffic accidents of a freeway. The micro-scale driving behaviors in rainy weather and possible vehicle rear-end and sideslip accidents are anal...The aim of this work is to investigate the influence of rainy weather on traffic accidents of a freeway. The micro-scale driving behaviors in rainy weather and possible vehicle rear-end and sideslip accidents are analyzed. An improved CA model of two lanes one-way freeway is presented, where some vehicle accidents will occur when the necessary conditions are simultaneously satisfied. The characteristics of traffic flow under different rainfall intensities are discussed and the accident probabilities are analyzed via the simulation experiments by using variable speed limit(VSL) and incoming flow control. The results indicate that the measures are effective especially during heavy rainstorms or short-time heavy rainfall.According to different rainfall intensities, an appropriate strategy should be adopted in order to reduce the probability of vehicle accidents and enhance traffic flux as well.展开更多
The cold wave weather process in Jiujiang in the early spring of February 2020 was analyzed.The results show that the establishment of blocking high near Lake Baikal and the rapid southward of cold air after accumulat...The cold wave weather process in Jiujiang in the early spring of February 2020 was analyzed.The results show that the establishment of blocking high near Lake Baikal and the rapid southward of cold air after accumulation resulted in the cold wave weather accompanied by strong cooling,hale and rain(snow)weather in Jiujiang.Before the cold wave broke out,the ground warmed up significantly,which was also one of thermal conditions for this cold wave weather.Water vapor conditions were abundant at middle and low levels;at 850 hPa,temperature dropped by 12-14℃during February 14-15,and-4℃isotherm appeared in the southern part of central Jiangxi,which is a favorable condition for rain(snow)in most areas of Jiujiang.展开更多
[Objective]The research aimed to analyze irregular information of the local rainstorm process (during 5-6 September,2009) in autumn continuous rainy weather in north Shaanxi. [Method] Based on V-3θ chart, routine obs...[Objective]The research aimed to analyze irregular information of the local rainstorm process (during 5-6 September,2009) in autumn continuous rainy weather in north Shaanxi. [Method] Based on V-3θ chart, routine observation data provided by Micaps system, satellite cloud chart and data at 100 automatic meteorological stations of Shaanxi, for rainstorm process in autumn continuous rainy weather in north Shaanxi during 4-10 September, 2009, by using structure analysis method, irregular information in local rainstorm weather was analyzed. [Result]In whole precipitation process, atmospheric structure in rainstorm zone presented obvious evolution process. Before precipitation, typical atmospheric structure information of the sudden convective weather appeared. Obvious ultra-low temperature structure appeared at 200 hPa, and consistent clockwise rotation flow was at vertical wind field. Meanwhile, water vapor was sufficient, and unstable energy existed at low layer. Structure characteristic of the convective strong precipitation appeared by advancing for 12h. As precipitation weakened, unstable energy was released, and ultra-low temperature disappeared. [Conclusion]The research provided some thoughts for the forecast of such weather process.展开更多
Objective:Many researches have demonstrated the effects of the extreme cold ambient temperature on the risk of out-of-hospital cardiac arrest(OHCA);yet,the results have been inconsistent.We performed a meta-analysis t...Objective:Many researches have demonstrated the effects of the extreme cold ambient temperature on the risk of out-of-hospital cardiac arrest(OHCA);yet,the results have been inconsistent.We performed a meta-analysis to evaluate whether extreme cold ambient temperature is related to OHCA.Methods:We searched for time-series studies reporting associations between extreme cold ambient temperature and OHCA in PubMed,web of science and Cochrane database.Results:Six studies involving 2337403 cases of OHCA were qualified for our meta-analysis.The odds ratio(OR)of OHCA was significantly increased in extreme cold weather(defined as the 1st or 5th centile temperature year-round)compared to reference temperature(as the 25th centile temperatures or daily mean temperature with minimum risk of OHCA)(OR=1.49,95%CI 1.18-1.88).The subgroup analysis for the elderly and the female failed to detect the influence of extreme cold weather on OHCA,the ORs are 1.25(95%CI 0.89-1.75)and 1.19(95%CI 0.87-1.64),respectively.Conclusion:The risk of OHCA is significantly higher in extreme cold ambient temperatures than in reference temperature,according to a relative temperature scale with percentiles of the region-specific temperature distribution.展开更多
Low temperature together with snow/freezing rain is disastrous in winter over southern China.Previous studies suggest that this is related to the sea surface temperature(SST)anomalies,especially La Nina conditions,ove...Low temperature together with snow/freezing rain is disastrous in winter over southern China.Previous studies suggest that this is related to the sea surface temperature(SST)anomalies,especially La Nina conditions,over the equatorial central–eastern Pacific Ocean(EP).In reality,however,La Nina episodes are not always accompanied by rainy/snowy/icy(CRSI)days in southern China,such as the case in winter 2020/2021.Is there any other factor that works jointly with the EP SST to affect the winter CRSI weather in southern China?To address this question,CRSI days are defined and calculated based on station observation data,and the related SST anomalies and atmospheric circulations are examined based on the Hadley Centre SST data and the NCEP/NCAR reanalysis data for winters of1978/1979–2017/2018.The results indicate that the CRSI weather with more CRSI days is featured with both decreased temperature and increased winter precipitation over southern China.The SSTs over both the EP and the southeastern Indian Ocean(SIO)are closely related to the CRSI days in southern China with correlation coefficients of-0.29 and 0.39,significant at the 90%and 95%confidence levels,respectively.The SST over EP affects significantly air temperature,as revealed by previous studies,with cooler EP closely related to the deepened East Asian trough,which benefits stronger East Asian winter monsoon(EAWM)and lower air temperature in southern China.Nevertheless,this paper discovers that the SST over SIO affects precipitation of southern China,with a correlation coefficient of 0.42,significant at the 99%confidence level,with warmer SIO correlated with deepened southern branch trough(SBT)and strengthened western North Pacific anomalous anticyclone(WNPAC),favoring more water vapor convergence and enhanced precipitation in southern China.Given presence of La Ni?a in both winters,compared to the winter of 2020/2021,the winter of 2021/2022 witnessed more CRSI days,perhaps due to the warmer SIO.展开更多
In most areas of China, affected by the environment of low temperature and high humidity, the wind speed sensor and wind direction sensor are frozen and cannot output data in autumn, winter or the alternation of winte...In most areas of China, affected by the environment of low temperature and high humidity, the wind speed sensor and wind direction sensor are frozen and cannot output data in autumn, winter or the alternation of winter and spring. In order to solve the freezing situation of the wind sensor, this paper designs a new type of antifreeze wind speed sensor. After meteorology performance testing and field observation tests, the correlation coefficient of the observation data is demonstrated, and the data curve is fitted. The result shows the sensor is stable, and has a good antifreeze effect, the data output is reliable.展开更多
The feature bends and tunnels of mountainous expressways are often affected by bad weather,specif-ically rain and fog,which significantly threaten expressway safety and traffic efficiency.In order to solve this proble...The feature bends and tunnels of mountainous expressways are often affected by bad weather,specif-ically rain and fog,which significantly threaten expressway safety and traffic efficiency.In order to solve this problem,a vehicle–road coordination system based on the Internet of Things(IoT)is developed that can share vehicle–road information in real time,expand the environmental perception range of vehicles,and realize vehicle–road collaboration.It helps improve traffic safety and efficiency.Further,a vehicle–road cooperative driving assistance system model is introduced in this study,and it is based on IoT for improving the driving safety of mountainous expressways.Considering the influence of rain and fog on driving safety,the interaction between rainfall,water film,and adhesion coefficient is analyzed.An intelligent vehicle–road coordination assistance system is constructed that takes in information on weather,road parameters,and vehicle status,and takes the stopping sight distance model as well as rollover and sideslip model as boundary constraints.Tests conducted on a real expressway demonstrated that the assistance system model is helpful in bad weather conditions.This system could promote intelligent development of mountainous expressways.展开更多
文摘Continuous rainy and cold weather in Yiwu in early spring of 2009 was analyzed.The results showed that the continuous rainy and cold weather occurred after temperature increased in early days.It is mainly because that the high geopotential height near Ural Mountains lasted for a long time,while the geopotential height was abnormally low in the east of central Asia.Meanwhile,the low-pressure trough in the south of Qinghai- Tibet Plateau was very active and moved towards the east frequently,and subtropical high was strong.Compared with continuous rainy and cold weather in early 2008,during the process of this continuous rainy and cold weather in 2009,the decrease in sea surface temperature of the middle and eastern Pacific Ocean near the equator was weaker;the blocking high pressure was slightly weaker,and the low pressure over Mongolia was strong;subtropical high was stronger and showed zonal distribution;south trough was slightly weaker.Compared with the previous continuous rainy and cold weather,the duration of this continuous rainy and cold weather in 2009 was not the longest,and its sunshine hours were not the least,but its temperature was higher,which might result from obvious increase of temperature in the early days.The research could provide scientific references for the prediction of continuous rainy and cold weather in future.
基金supported jointly by the National Basic Research Program of China (Grant No. 2010CB 428603)the National Natural Science Foundation of China (Grants Nos. 41250110073, 41350110331 and 41025017)+1 种基金the Chinese Academy of Sciences fellowship for young international scientists (Grant No. 2011Y2ZZB05)a China postdoctoral science foundation grant (Grant No. 2013M541010)
文摘Reflection of stratospheric planetary waves and its impact on tropospheric cold weather over Asia during January 2008 were investigated by applying two dimensional Eliassen–Palm(EP) flux and three-dimensional Plumb wave activity fluxes. The planetary wave propagation can clearly be seen in the longitude–height and latitude–height sections of the Plumb wave activity flux and EP flux, respectively, when the stratospheric basic state is partially reflective. Primarily, a wave packet emanating from Baffin Island/coast of Labrador propagated eastward, equatorward and was reflected over Central Eurasia and parts of China, which in turn triggered the advection of cold wind from the northern part of the boreal forest regions and Siberia to the subtropics. The wide region of Central Eurasia and China experienced extreme cold weather during the second ten days of January 2008, whereas the extraordinary persistence of the event might have occurred due to an anomalous blocking high in the Urals–Siberia region.
文摘Based on the conventional high-and low-altitude and surface observation data,the weather analysis and diagnosis methods were applied to analyze the cold wave process of Ulanqab in January 2016 from the aspects of weather reality,circulation background,weather causes,and forecast test.The results show that strong cold air accumulated gradually near Lake Baikal and Central Siberia,affecting the city in a northwest path.During the cold wave process,the transverse trough moved southwards slowly at 500 hPa,and the ground cold high pressure was strong and stable.The cold air continued to move southwards,resulting in the strong cold wave and gale weather with a large impact range and long duration.The high-altitude jet at 300 hPa strengthened the cold wave pile,which was conducive to the outbreak of the cold wave.The intensity and location changes of the 500 hPa positive vorticity center,850 hPa cold advection region and 24-h ground pressure variation well showed the intensity of the cold wave process and the variation of the affected region.The influence of strong cold advection,ground positive pressure variation,and strong vertical wind shear were the main reasons for a strong drop in temperature and gale weather in this process.The test results of prediction reveal that the forecast value of the maximum temperature were relatively lower than the actual value,while the forecast of the minimum temperature was more accurate.The three warning signals were issued timely and accurately.The circulation pattern predicted by numerical models was more accurate in the early stage of the process,but there was an error in the late stage,and the forecast system moved slower than the actual situation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.41205040 and 41375078)the State Key Development Program for Basic Research,China(Grant No.2012CB955203)the Special Scientific Research Project for Public Interest(Grant No.GYHY201306021)
文摘Considering the differences between the Northeast China Cold Vortex(CV) and the Mid-Summer(MS) rainy period and their corresponding atmospheric circulations are comprehensively analyzed, and the objective identification methods of defining the annual beginning and ending dates of Northeast China CV and MS rainy periods are developed respectively.The annual beginning date of the CV(MS) rainy period is as follows. In a period from April to August, if daily regional mean precipitation ryi is larger than yearly regional mean precipitation R(or 2R) on a certain day, the station precipitation rs is larger than the station yearly mean precipitation r(or 2 r) in at least 50% of stations in Northeast China, and this condition is satisfied in the following 2(7) days, then this date is defined as the beginning date of the CV(MS) rainy period.While the definition of the ending date of the MS rainy period shows the opposite process to its beginning date. With this objective identification method, the multi-year average(1981–2010) beginning date of the CV rainy period is May 3, the beginning date of the MS rainy period is June 27, the ending day of the CV rainy period is defined as the day before the beginning date of the MS rainy period, and the ending date of the MS rainy period is August 29. Meanwhile, corresponding anomaly analysis at a 500-h Pa geopotential height, 850-h Pa wind, Omega and relative humidity fields all show that the definitions of the average beginning and ending dates of the CV and MS rainy periods have a certain circulation meaning.Furthermore, the daily evolution of the CV index, meridional and zonal wind index, etc. all show that these objectively defined beginning and ending dates of the CV and MS rainy periods have climate significance.
文摘The article is devoted to a discussion of the possibilities of biometeorological assessment of the severity of weather conditions during the cold season.The relevance of the study is ensured not only by the fact that residents of a number of states,whose total number is more than 27 million people,live in these extreme climatic conditions,but also by the need to improve biometeorological approaches to assessing the impact of these conditions on the body and health of the population.This study examined biometeorological characteristics that illustrate a measure of cold stress.These include the Siple wind-chill index;Bodman winter severity index;Arnoldi weather hardness coefficient;Mountain wind chill index;weather hardness coefficient according to I.M.Osokin.The results of a comparison of winter severity assessments based on the values of the calculated Siple and Bodman indices made it possible to establish that the Bodman index is more acceptable when assessing mildly severe winters.The most adequate for assessing the“severity”of the cold period against the background of a decrease in air temperature and an increase in wind speed is the Siple index.The need to provide the countries of the world with high-quality hydrometeorological and biometeorological forecast information is justified and relevant.In this regard,these studies are very promising.
基金Supported by Special Item of Climate Variation of China Meteorologcal Administration (CCSF2011-25)Guangxi Science Foundation Item (Guiqingke 0991060)
文摘[Objective] The research aimed to study the variation characteristics of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years.[Method] Based on the daily average temperature data from 1961 to 2010 at 88 meteorological stations in Guangxi,yearly days and end date of low temperature and rainy weather during spring sowing period were carried out statistics.The variation characteristics of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years were analyzed by using linear tendency calculation,phased analysis,Morlet wavelet analysis and correlation analysis.Moreover,the influences of climate warming on days and end date of low temperature and rainy weather in spring sowing period were analyzed.[Result] The average days of low temperature and rainy weather in Guangxi during spring sowing period from 1961 to 2010 was during 3.5-23.2 d.The regional distribution characteristics were that it was more in northeast and mountain zone,and less in southwest and valley.The regional distribution characteristics of end date were that it was late in northeast and mountain zone,and early in southwest and valley.The days of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years presented slight decrease trend,and the end date presented slight advancing trend.The phased variation characteristics of days and end date of low temperature and rainy weather were obvious.The days of low temperature and rainy weather from the early 1980s to metaphase of 1990s was obviously more,and the end date was obviously later.After the 1990s,the days of low temperature and rainy weather was obviously less,and the end date was obviously earlier.The days of low temperature and rainy weather had periodic oscillation signals of 4,6,8,10-14 years.The end date had periodic oscillation signals of 6,12-14 years.The days and end date of low temperature and rainy weather in Guangxi during spring sowing period significantly related to average temperature from middle dekad of February to first dekad of April.The climate warming made that the days of low temperature and rainy weather tended to decrease,and the end date tended to advance.[Conclusion] The research provided reference for further understanding the occurrence rule of low temperature and rainy weather,going after profits and avoiding disadvantages,reasonably arranging production,carrying out correlated research.
文摘Objective:To investigate the effect of cold weather on carotid artery stenosis and occlusion.Methods:We conducted a retrospective observational study,in which 145 patients with carotid artery stenosis and occlusion were enrolled[115 men and 30 women;the mean age was 61.08 years(95%CI 59.27-62.88)].Patients were divided into the low-temperature group(n=98)(≤12℃)and the non-low temperature group(n=47)(>12℃).Clinical characteristics,blood pressure,National Institutes of Health Stroke Scale(NIHSS),blood fat,and blood viscositys were compared between the two groups.Correlation between NIHSS and mean daily temperature was analyzed.Results:There was no significant difference in the systolic and diastolic blood pressure between the two groups(P>0.05).The NIHSS score was slightly higher in the non-low temperature group compared to that of the low-temperature group(U=2984,P<0.01).Glycemia,cholesterol level,prothrombin time,fibrinogen,and International Normalized Ratio did not show any significant difference(P>0.05).Correlation analysis showed a very low positive and statistically significant correlation between ambient temperature and NIHSS score(r=0.18,P=0.029).Conclusion:Cold weather does not impact blood pressure,blood cholesterol,and coagulation factors of patients with carotid artery stenosis and occlusion.The neurological deficit is more severe in the non-low ambient temperature group.A potential relationship exists between ambient temperature and the level of neurological impairment.
文摘Application of weathering and cold-formed steel in transmission lines can reduce steel consumption and environmental pollution. Some advances in the studies on the weathering and cold-formed steel in transmission tower are introduced. Firstly, corrosion-resistant tests of weathering steel samples under different simulating technical atmospheres were carried out separately for 240 hours. It shows that the corrosion degree of joint samples is higher than that of single chip samples, and the corrosion-resistant performance of weathering steel is superior to common carbon steel. The corrosion-resistance of weathering steel meets with the requirement of transmission tower. Secondly, experiments and finite element analysis for cold-formed angles and a 220kV prototype tower were completed, and the stability coeffi-cient fitting curves as well as the modification formulas of slenderness ratio for cold-formed members were determined. According to the structural characteristics of transmission towers, four sections of cold-formed angles with different sections and slenderness ratios were selected in this study. The finite element model well predicted the buckling behav-iour of the cold-formed members. Ultimate loads calculating by the fitting curve were well agreed to the experimental values, especially for the members with small slenderness ratios. Weight of the cold-formed steel tower can be reduced by more than 5 percent after considering the strength enhancement. Cost of the weathering and cold-formed steel transmission tower is nearly equivalent to that of hot-rolled steel tower with hot galvanizing.
基金the National Natural Science Foundation of China(Grant No.41731173)the National Key R&D Program of China(Grant No.2019YFA0606701)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB42000000 and XDA20060502)the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(Grant No.GML2019ZD0306)the Innovation Academy of South China Sea Ecology and Environmental Engineering,the Chinese Academy of Sciences(Grant No.ISEE2018PY06)。
文摘China experienced significant flooding in the summer of 2020 and multiple extreme cold surges during the winter of 2020/21.Additionally,the 2020 typhoon season had below average activity with especially quiet activity during the first half of the season in the western North Pacific(WNP).Sea surface temperature changes in the Pacific,Indian,and Atlantic Oceans all contributed to the heavy rainfall in China,but the Atlantic and Indian Oceans seem to have played dominant roles.Enhancement and movement of the Siberian High caused a wavier pattern in the jet stream that allowed cold polar air to reach southward,inducing cold surges in China.Large vertical wind shear and low humidity in the WNP were responsible for fewer typhoons in the first half of the typhoon season.Although it is known that global warming can increase the frequency of extreme weather and climate events,its influences on individual events still need to be quantified.Additionally,the extreme cold surge during 16–18 February 2021 in the United States shares similar mechanisms with the winter 2020/21 extreme cold surges in China.
基金supported by the National Natural Science Foundation of China(Grant No.50478088)the Natural Science Foundation of Hebei Province,China(Grant No.E2015202266)
文摘The aim of this work is to investigate the influence of rainy weather on traffic accidents of a freeway. The micro-scale driving behaviors in rainy weather and possible vehicle rear-end and sideslip accidents are analyzed. An improved CA model of two lanes one-way freeway is presented, where some vehicle accidents will occur when the necessary conditions are simultaneously satisfied. The characteristics of traffic flow under different rainfall intensities are discussed and the accident probabilities are analyzed via the simulation experiments by using variable speed limit(VSL) and incoming flow control. The results indicate that the measures are effective especially during heavy rainstorms or short-time heavy rainfall.According to different rainfall intensities, an appropriate strategy should be adopted in order to reduce the probability of vehicle accidents and enhance traffic flux as well.
文摘The cold wave weather process in Jiujiang in the early spring of February 2020 was analyzed.The results show that the establishment of blocking high near Lake Baikal and the rapid southward of cold air after accumulation resulted in the cold wave weather accompanied by strong cooling,hale and rain(snow)weather in Jiujiang.Before the cold wave broke out,the ground warmed up significantly,which was also one of thermal conditions for this cold wave weather.Water vapor conditions were abundant at middle and low levels;at 850 hPa,temperature dropped by 12-14℃during February 14-15,and-4℃isotherm appeared in the southern part of central Jiangxi,which is a favorable condition for rain(snow)in most areas of Jiujiang.
基金jointly supported by the National Key R&D Program of China [grant number 2016YFA0600701]the National Natural Science Foundation of China [grant numbers41675083 and 41210007]the CAS–PKU Joint Research Program
文摘[Objective]The research aimed to analyze irregular information of the local rainstorm process (during 5-6 September,2009) in autumn continuous rainy weather in north Shaanxi. [Method] Based on V-3θ chart, routine observation data provided by Micaps system, satellite cloud chart and data at 100 automatic meteorological stations of Shaanxi, for rainstorm process in autumn continuous rainy weather in north Shaanxi during 4-10 September, 2009, by using structure analysis method, irregular information in local rainstorm weather was analyzed. [Result]In whole precipitation process, atmospheric structure in rainstorm zone presented obvious evolution process. Before precipitation, typical atmospheric structure information of the sudden convective weather appeared. Obvious ultra-low temperature structure appeared at 200 hPa, and consistent clockwise rotation flow was at vertical wind field. Meanwhile, water vapor was sufficient, and unstable energy existed at low layer. Structure characteristic of the convective strong precipitation appeared by advancing for 12h. As precipitation weakened, unstable energy was released, and ultra-low temperature disappeared. [Conclusion]The research provided some thoughts for the forecast of such weather process.
基金supported by the National Key Technology R&D Program(2018YFC2000301)from the Ministry of Science and Technology of China.
文摘Objective:Many researches have demonstrated the effects of the extreme cold ambient temperature on the risk of out-of-hospital cardiac arrest(OHCA);yet,the results have been inconsistent.We performed a meta-analysis to evaluate whether extreme cold ambient temperature is related to OHCA.Methods:We searched for time-series studies reporting associations between extreme cold ambient temperature and OHCA in PubMed,web of science and Cochrane database.Results:Six studies involving 2337403 cases of OHCA were qualified for our meta-analysis.The odds ratio(OR)of OHCA was significantly increased in extreme cold weather(defined as the 1st or 5th centile temperature year-round)compared to reference temperature(as the 25th centile temperatures or daily mean temperature with minimum risk of OHCA)(OR=1.49,95%CI 1.18-1.88).The subgroup analysis for the elderly and the female failed to detect the influence of extreme cold weather on OHCA,the ORs are 1.25(95%CI 0.89-1.75)and 1.19(95%CI 0.87-1.64),respectively.Conclusion:The risk of OHCA is significantly higher in extreme cold ambient temperatures than in reference temperature,according to a relative temperature scale with percentiles of the region-specific temperature distribution.
基金Supported by the National Natural Science Foundation of China(42088101)Joint Open Project of KLME&CIC-FEMD,NUIST(KLME202212)。
文摘Low temperature together with snow/freezing rain is disastrous in winter over southern China.Previous studies suggest that this is related to the sea surface temperature(SST)anomalies,especially La Nina conditions,over the equatorial central–eastern Pacific Ocean(EP).In reality,however,La Nina episodes are not always accompanied by rainy/snowy/icy(CRSI)days in southern China,such as the case in winter 2020/2021.Is there any other factor that works jointly with the EP SST to affect the winter CRSI weather in southern China?To address this question,CRSI days are defined and calculated based on station observation data,and the related SST anomalies and atmospheric circulations are examined based on the Hadley Centre SST data and the NCEP/NCAR reanalysis data for winters of1978/1979–2017/2018.The results indicate that the CRSI weather with more CRSI days is featured with both decreased temperature and increased winter precipitation over southern China.The SSTs over both the EP and the southeastern Indian Ocean(SIO)are closely related to the CRSI days in southern China with correlation coefficients of-0.29 and 0.39,significant at the 90%and 95%confidence levels,respectively.The SST over EP affects significantly air temperature,as revealed by previous studies,with cooler EP closely related to the deepened East Asian trough,which benefits stronger East Asian winter monsoon(EAWM)and lower air temperature in southern China.Nevertheless,this paper discovers that the SST over SIO affects precipitation of southern China,with a correlation coefficient of 0.42,significant at the 99%confidence level,with warmer SIO correlated with deepened southern branch trough(SBT)and strengthened western North Pacific anomalous anticyclone(WNPAC),favoring more water vapor convergence and enhanced precipitation in southern China.Given presence of La Ni?a in both winters,compared to the winter of 2020/2021,the winter of 2021/2022 witnessed more CRSI days,perhaps due to the warmer SIO.
文摘In most areas of China, affected by the environment of low temperature and high humidity, the wind speed sensor and wind direction sensor are frozen and cannot output data in autumn, winter or the alternation of winter and spring. In order to solve the freezing situation of the wind sensor, this paper designs a new type of antifreeze wind speed sensor. After meteorology performance testing and field observation tests, the correlation coefficient of the observation data is demonstrated, and the data curve is fitted. The result shows the sensor is stable, and has a good antifreeze effect, the data output is reliable.
基金the Project of Zhejiang Provincial Transportation Department(No.2020059)。
文摘The feature bends and tunnels of mountainous expressways are often affected by bad weather,specif-ically rain and fog,which significantly threaten expressway safety and traffic efficiency.In order to solve this problem,a vehicle–road coordination system based on the Internet of Things(IoT)is developed that can share vehicle–road information in real time,expand the environmental perception range of vehicles,and realize vehicle–road collaboration.It helps improve traffic safety and efficiency.Further,a vehicle–road cooperative driving assistance system model is introduced in this study,and it is based on IoT for improving the driving safety of mountainous expressways.Considering the influence of rain and fog on driving safety,the interaction between rainfall,water film,and adhesion coefficient is analyzed.An intelligent vehicle–road coordination assistance system is constructed that takes in information on weather,road parameters,and vehicle status,and takes the stopping sight distance model as well as rollover and sideslip model as boundary constraints.Tests conducted on a real expressway demonstrated that the assistance system model is helpful in bad weather conditions.This system could promote intelligent development of mountainous expressways.
