Harm of Hail to Crops and Countermeasures of Artificial Hail Suppression in Ulanqab City

Hail is one of meteorological disasters affecting crop growth in Ulanqab City.It happens frequently from May to September,and this period is also the main growing season of crops.In this period,hail will cause damage to crops,make farmland soil harden,and bring varying degrees of harm to agricultural production.Artificial hail suppression is an important scientific and technological means for disaster prevention and mitigation.It is necessary to strengthen the monitoring,analysis and forecast of severe convection weather,intensify the release of early warning information of hail weather,provide accurate and reliable real-time information for the implementation of artificial hail suppression operations,strengthen the implementation of artificial weather modification,effectively carry out artificial hail suppression operations,and avoid and reduce the impact of hail disaster.

Analysis of a Large-scale Hail Process in Ulanqab City

Based on the weather monitoring data,NCEP/NCAR reanalysis data and Doppler weather radar data,the circulation background,atmospheric stability and changing characteristics of radar echoes of a large-scale hail weather process in Ulanqab City on July 5,2021 were analyzed.The results show that this hail weather process occurred in the summer afternoon of the hail-prone period in Ulanqab City,and was formed under the influence of upper trough and the circulation background of"two troughs and one ridge",which was conducive to the occurrence of strong convection weather.The low-level shear line provided the dynamic and water vapor conditions for the occurrence of the hail.In strong convection weather,water vapor was transported mainly from the Bay of Bengal,India and Nepal over the Himalayas.Before the occurrence of strong convection weather,water vapor transport increased significantly,and the low-level water vapor concentrated below 400 hPa,with obvious convergence and vertical transport.The characteristic parameters of radar echoes,such as combined reflectivity,vertically integrated liquid,and echo top height,increased significantly before and during the occurrence of hail,which had good indicative significance for the prediction and early warning of hail.

Will Online Car-Hailing Affect Consumers’ Decisions about Automobile Purchase?—An Empirical Study Based on Questionnaire Investigation

The online car-hailing industry, which provides the right of use, has a certain impact on the traditional automobile market, but there is no unified theory on whether it has a positive impact or a negative impact. Based on 362 consumer questionnaire data, this study builds a structural equation model to discuss the driving factors of residents’ choice of online car-hailing and whether the development of online car-hailing will have a certain substitution impact on the sales of private cars. From the perspective of consumers’ purchase intention, the research results show that consumers’ price consciousness, convenience consciousness, environmental protection consciousness and possession tendency will affect their choice of travel mode, and the use of online car-hailing is positively correlated with consumers’ willingness to replace private car ownership with online car-hailing.

网约车对传统出租车使用量的影响——基于广东城市的实证分析

基于广东省21个城市的样本,收集2010—2016年平衡面板数据,采用连续型双重差分法(连续型DID),探究网约车与传统出租车使用量之间的因果关系,并进行一系列稳健性检验。研究结果表明:(1)网约车会对传统出租车使用量产生显著的负向影响;(2)进一步的分析表明这种负向影响在“珠三角地区”城市中更为严重。此结果表明网约车对城市传统出租车使用量的影响在“珠三角地区”和非“珠三角地区”存在异质性。以上结果表明:在广东城市中需要展开网约车治理,在“珠三角地区”城市中显得更为迫切;传统出租车经营者很有必要做出改革、创新以寻求行业的长远发展。

Risk Assessment of Hail Disaster on Cotton——A Case Study in Anhui Province

[Objective] The aim was to reveal the pattern of hail disaster risk for cotton in Anhui Province. [Method] Based on database of risk evaluation on hail disaster for cotton in Anhui Province, statistical inference and comprehensive indices measurement were made use of for extraction of disastrous index of hail （H） and loss rate of cotton （L）. Hail vulnerability curves in four stages （seedling, bud, boll and boll opening stages） of cotton were fitted by Matlab and SPSS software. Risk evaluation on hail disaster of cotton in Anhui Province was conducted and the related map was drawn on basis of yearly model of loss rate （by hail disaster）, as follows： Sa=n∑i=1Si-a∏i=1Si=1-（1-Si） [Result] In Anhui Province, high risk area by hail concentrates in northeast regions and mountainous regions in west of Anhui, and lower risk area is distributed in middle and down streams of Yangtze River and mountainous area in south of Anhui. [Conclusion] The research explored evaluation methods on hail risks based on the limited information, and could provide references for risk evaluation on hail disaster in other regions.

Analysis of Physical Quantities and Radar Parameters about Hail Shooting and Heavy Convective Rainfall

[Objective] The paper is to analyze physical quantities and radar parameter of hail shooting and heavy convective rainfall weather. [Method] Using radar data of Jinan station during 2002 and 2008, combined with sounding data, the physical quantities and radar parameter of hail shooting and heavy convective rainfall weather are compared and analyzed. [Result] The smaller Sl is conducive to the generation of hail weather. When K〉 35 ~C, the probability for occurrence of heavy rainfall weather is significantly increased; when K〈20 ^（3, the probability for occurrence of heavy rainfall weather is significantly decreased. When CAPE value is greater than 1 500 J/KG, the probability for occurrence of hail weather is significantly decreased, while the probability for occurrence of heavy rainfall weather is significantly in- creased. The possibility for occurrence of hail monomer is small when the wind shear is less than 5 m/s; and it is large while wind shear is greater than 20 m/s. The radar forecasting indexes of hail monomer is as follows： VIL value reaches 35 kg/m2 （May）, 43 kg/m2 （June and July）, the monomer height is greater than 9 km, the maximum reflectivity factor is larger than 60 dBz, strong center height reaches 3.3 km （May）, 4.3 km （June） and 5.5 km （July）; VlL value of heavy rainfall monomer generally is below 25 kg/m2. [Conclusion] The paper provides basis form prediction of hail and heavy rainfall.

内蒙古冰雹特征及基于机器学习的冰雹识别方法研究

利用1959—2021年内蒙古人工观测冰雹记录,分析冰雹分布的时空特征,并基于机器学习算法构建了冰雹识别方法。结果表明:(1)时间分布上,冰雹事件出现的站数和站日数均呈现下降趋势;空间分布上,冰雹多集中在阴山山脉和大兴安岭一带,冰雹多发区沿山脉伸展分布。(2)冰雹发生具有明显的季节变化和日变化特征,每年5—9月是冰雹频发月份,占全年雹日的91.79%,雹日中12:00—19:00是冰雹的多发时段。(3)利用随机森林、LightGBM、K近邻和决策树4种机器学习算法,通过数据预处理、预报因子选择、模型训练、模型调优等步骤,对内蒙古冰雹天气过程进行建模与评估。评估结果表明,采用机器学习方法可以有效地识别冰雹天气过程,各模型的TS评分均达到0.83以上,命中率达到92%以上,随机森林算法在测试集上识别效果最优。研究结果可为内蒙古冰雹预报预警和人工防雹工作提供参考。

江西春季一次大冰雹的雷达回波特征分析

为更好地做好冰雹天气的监测预警工作,使用MICAPS天气图、雷达拼图、雷达PUP产品等资料,采用天气学和雷达气象学原理与研究方法,对2021年3月30-31日江西大冰雹过程进行分析。结果表明:(1)500 hPa低槽、850 hPa西南急流、925 hPa切变线和地面倒槽等天气系统,以及大气层结具有“上干下湿”有利条件。(2)≥5 cm的大冰雹回波系统有孤立超级单体和回波带上超级单体两种。其共同特征是:回波强度≥60 dBZ,并有65 dBZ以上的回波核;60 dBZ强回波面积≥100 km^(2);30~60 dBZ强回波梯度(最密集区域距离)≤7 km和具有云砧回波。(3)垂直积分液态水含量(VIL)达到60 kg/m^(2);径向速度V0.5°仰角具有正负速度对;反射率因子垂直剖面(RCS)有悬挂、穹窿、回波墙等特殊回波结构;径向速度垂直剖面(VCS)具有辐合型气旋结构。(4)超级单体在3 km等高平面显示(CAPPI)上,反射率因子都在60 dBZ以上,有65 dBZ回波核,风场处于辐合型气旋性环流中。上述研究结果有助于大冰雹天气雷达回波特征的认识和应用。

Diagnostic Analysis on A Hail Storm Occurred in Dalian Area

By using regular meteorological data and Doppler radar data,causes for a hail storm over northern area of Dalian on Oct.13,2009 were analyzed from several aspects,including synoptic background,T-LnP charts and the characteristics of radar reflectivity factor evolution.The results showed that the hail storm occurred in downstream of 500 hPa trough.The 500 hPa cold trough turned zonally and triggered the formation of shear line on lower level.Before the hail event,instability energy and moisture supply were observed.The shear line on lower level intensified the atmospheric instability,promoted the release of potential energy,caused the hail event.The cooperation of upper and lower level jet streams provided favorable dynamic condition for strong convection development.The Doppler radar analysis showed that strong convection was comprised of multiple convection cells,which demonstrated 'L' and 'V' shapes during mature stage,with peak intensity of 50-60 dBz.

基于双偏振雷达和FY-4A卫星资料的一次湖南秋季强冰雹预警特征分析

为提升秋季冰雹监测预警能力,基于双偏振雷达和风云四号A星(FY-4A)资料,对2023年11月湖南一次罕见的秋季强冰雹过程进行分析,探讨其预警特征。研究发现:(1)强冰雹由超级单体风暴产生,在降雹阶段,强回波中心(水平反射率因子Z H≥65 dBz)底部接近地面,相关系数(CC)<0.9,差分传播相移率(K DP)为空洞,差分反射率因子(Z DR)为-3~0 dB,对应直径≥5 cm的大冰雹降落,与实况吻合。(2)Z DR柱上升和下降可表征上升气流的加强和减弱,Z DR结合CC有助于识别三体散射(TBSS)和旁瓣特征。强回波面积和质心高度对超级单体风暴不同发展阶段有很好的指示作用,结合监测可使冰雹预警提前量达12 min以上。此次过程超级单体造成的TBSS长度达到罕见的73 km,TBSS的出现、风暴顶辐散呈明显减弱趋势较降雹时间提前17 min以上。(3)冰雹、雷暴大风发生区域与冰雹云黑体亮温(TBB)、云顶温度(CTT)、云顶高度(CTH)、云顶气压(CTP)梯度大值区对应较好。结合雷达分析冰雹云发展过程发现,可将TBB≤-58℃,CTT≤-56℃,CTH≥13 km,CTP≤180 hPa且TBB≤-52℃面积持续增大作为FY-4A卫星秋季冰雹云特征参量的监测预警指标。(4)TBB最大递减率发生时间较降雹时间提前11 min以上。13.3μm和10.8μm通道亮温差对冰雹云的发展和减弱反应最为敏感,6.5μm和10.8μm通道亮温差则在单站对流监测指标中对冰雹过境前后较其他亮温差反应敏感。

The Role of Initial Cloud Condensation Nuclei Concentration in Hail Using the WRF NSSL 2-moment Microphysics Scheme

The effects of the initial cloud condensation nuclei （CCN） concentrations （100-3000 mg-1） on hail properties were investigated in an idealized non-severe hail storm experiment using the Weather Research and Forecasting （WRF） model, with the National Severe Storms Laboratory 2-moment microphysics scheme. The initial CCN concentration （CCNC） had obvious non-monotonic effects on the mixing ratio, number concentrations, and radius of hail, both in clouds and at the surface, with a CCNC threshold between 300 and 500 mg-1. An increasing CCNC is conducive （suppressive） to the amount of surface hail precipitation below （above） the CCNC threshold. The non-monotonic effects were due to both the thermodynamics and microphysics. Below the CCNC threshold, the mixing ratios with the increasing CCNC, resulting in more latent heat released of cloud droplets and ice crystals increased dramatically from condensation and frozen between 4 and 8 km and intensified updraft volume. The extent of the riming process, which is the primary process for hail production, increased dramatically. Above the CCNC threshold, the mixing ratio of cloud droplets and ice crystals increased continuously, but the maximum updraft volume was weakened because of reduced frozen latent heating at low level. The smaller ice crystals reduced the formation of hail and smaller clouds, with decreased rain water reducing riming efficiency so that graupel and hail also decreased with increasing CCNC, which is unfavorable for hail growth.

Prevalence of intestinal parasite infections among patients in local public hospitals of Hail,Northwestern Saudi Arabia

Objective:To evaluate the prevalence of intestinal parasites among patients in Hail,Northwestern Saudi Arabia.Methods:Stool samples were collected from 130 patients(69females and 61 males) in Hail General Hospital.Each sample was examined by direct wet mount microscopic examination using both normal saline and Lugol's iodine preparation and concentration techniques using salt and formol-ether solutions.Permanent stained smears were performed for intestinal coccidian using modified Ziehl-Neelsen technique.Results:The overall prevalence of intestinal parasitic infection was 45.38%(59 cases).Forty-four(33.84%)were found to be infected with one or more intestinal protozoa.5(3.84%) were infected with helminthes and 10(7.69%) had mixed infection with both helminthes and protozoa.The most common intestinal helminth detected was Ancyloxtoma duvdenale(n=5.3.84%),followed by Ascaris lumlmcnidex.Taenia sp.and Trichuris trichiura(n=2 for each species,1.5%).For intestinal protozoa,the coccidian Cryptosporidium parvum(n=25,19.23%) was the most common followed by Entamoeba histolytica/dispur(n=21,16.15%),Giurdia lamblia(n=15,11.54%),Entamoeba coli(n=5.3.85%) and Blastocysts hominis(n=3,2.30%).The prevalence of intestinal parasitic infections in females was significantly higher than in males(P<0.05).Conclusions:This is the first study highlighting that intestinal parasites are still an important public health problem in Northwestern Saudi Arabia Therefore,health education would be the best way to prevent from intestinal parasite infections which are mainly food borne diseases.

Distribution Characteristics of Heavy Metals and Grain Size of Sediments from Hailing Bay, China

The geochemical properties of sediment in the nearby seawater areas of Hailing Bay of the western Guangdong province were first time investigated in the dry period of 2001 and the flood period of 2002, respectively. The temporal and spatial characteristics of Cu, Pb, Zn, Cd and Hg concentrations, organic carbon and total sulfides contents, and granulometric distribution in the surface sediment from the Hailing Bay were analyzed. Results demonstrated that there were no remarkable changes in the composition of sediment between the dry period and the flood period; the average concentrations of Cu, Pb, Zn, Cd and Hg were 32.1 ± 17.5, 36.1 ± 10.0, 107.0 ± 37.4, 0.26± 0.15 and 0.109 ± 0.073 mg·kg-1, respectively; the organic carbon and total sulfides contents were 1.33 ± 0.53 % and 140.13 ± 136.42 mg·kg-1, respectively; surface sediments were dominated by clayey silt and sand, and their mean grain size was 4.62 ± 2.36 φ and in the range 0.52-7.55 φ; there existed obvious correlation between the concentrations of Cu, Pb, Zn and Hg, and among Cu, Pb, Zn and Hg concentrations, organic carbon contents and grain size of sediments.

Analysis on the Hail Climate and Radar Characteristics in Linyi City

[Objective] The research aimed to study the hail climate and radar characteristics in Linyi City.[Method] The five representative stations which were Mengyin,Yishui,Linshu,Cangshan,Linyi and were collectively called as Linyi City in Yimeng mountain area were selected.From the hail path,weather situation and influence system,the 40 times hail weather processes which happened in every station in June during 1965-2008 were carried out the statistics analysis.The typical weather situation and physical structure characteristics in the hail weather process in Linyi City were studied.On this basis,the statistical analysis on the new generation weather radar characteristics in the hail process during 2003-2008 was carried out.The climatic index of hail occurrence,the characteristic index of radar data and the radar observation characteristic in the city were discussed.[Result] The weather systems which affected the hail shooting in Linyi City were Mongolia cold vortex type,eastward shift small trough type,northwest airflow cold temperature trough type and so on.On the 6 h ground chart before the hail shooting,there were the small low pressure,cold front or wind shear line(airflow convergence field) in Shandong Province.They had the 'trigger' and 'development' effects on the occurrence and development of strong convection hail shooting.The joining of small trough in the rear of 500 hPa low vortex had three forms that were the west small trough supplementary type,the airflow field divergence in front of vortex and the small trough in the rear of vortex southward swing in general.When the vertical liquid water content quickly increased from zero or the small amount to above 40 kg/m2,it was possible to generate the hail weather.In the different months,when the echo intensity of convective cloud body >50 dBz,the initial echo height >5 km,and the crown elevation,strong center height reached the certain values,it was possible to generate the hail weather.On the radar radial velocity chart,the meso-scale convective system characteristic(the bottom layer was the convergence,and the high layer was the divergence) was obvious.At 1.5° and 3.4° elevation angles in the middle layer,there was the strong wind shear in the vertical direction of convective storm monomer.[Conclusion] The research provided the certain reference value for the analysis and forecast of this kind of weather.

Diagnosis of An Infrequent Regional Hail Weather Course in Gansu

Based on routine weather charts, numerical predication products and satellite cloud images, the causes of an infrequent regional hail weather process occurred in east of Gansu on Aug. 2, 2006 were diagnosed and analyzed. The results showed that the hail weather process occurred at the abnormal large-scale circulation leading the system to west. When the cold trough, which was separated by the north cold vortex, moved southward through Hetao and then intersected with 300 hPa jet stream and the surface cold front, that led to the strong convection. There were strong upward motion and unstable stratification in hail area, three MCS in satellite cloud, and a character of formed arch shape echo on radar echo charts.

Climatic Characteristics of Hail Disaster and Division of Defense Region in Guizhou Province

[Objective] The aim was to study the climatic characteristics of hail disaster from 1984 to 2006 in Guizhou Province,China.[Method] Through statistical analysis,the climatic characteristics and disaster characteristics of hail from 1984 to 2006 in Guizhou Province were annalyzed and compared with previous results,then the classification standards of hail disaster were established,finally the defense zoning map of hail disaster in Guizhou Province was made.[Result] According to the statistical analysis on the historical data of hail disaster from 1984 to 2006,the frequency hail was 1 243 times in Guizhou in 23 years,that is,annual average frequency reached 54 times;annual average hailing days were 0.1-2.7 d in Guizhou Province,and the average frequency of hail was 3.8 times during each hail process;the frequency of hail was below 30 times in 52% of years and 30-80 times in 35% of years among 23 years.Hail could appear in the whole year,and 74% of hails occurred in spring,while winter had the fewest times.The results above were basically consistent with those of previous studies.Hail disaster mainly resulted in casualties and direct economic loss,and was divided into four grades according to direct economic loss,namely Grade I(extremely severe hail disaster),Grade II(severe hail disaster),Grade III(comparatively severe hail disaster) and Grade IV(medium hail disaster).The defense zoning map of hail disaster in Guizhou Province was made based on the frequency of hail and severe hail disaster,that is,the defense region at Grade I mainly distributed in Liupanshui City(in western Guizhou) and southern Guizhou;the defense region at Grade II was in the west,south and northeast of Guizhou Province,while the rest was at Grade III.[Conclusion] The study was of reference value for the defense of hail disaster in Guizhou Province.

Analysis on the Climatic Characteristics of Hail in the South Mountain Area of Ningxia

[Objective] The research aimed to study the climatic characteristics of hail in the southern mountain area of Ningxia in recent 50 years. [Method] Based on the hail observation data of 5 surface meteorological stations (Guyuan, Xiji, Jingyuan, Longde, Liupanshan) in the south of Ningxia during 1960-2009, the spatial distribution rule, the interannual and monthly climatic characteristics and variation trends of hail in the south mountain area of Ningxia were analyzed by using the statistical method. Moreover, the hail disaster prevention and reduction measures in Guyuan were put forward. [Result] The hail in the south mountain area of Ningxia in recent 50 years had the obvious annual, seasonal, monthly and daily variation characteristics. The hail might occur from March to October and mainly concentrated during May-August which occupied 72% in the whole year. The occurrence probability of hail in June was the biggest and occupied 21.7% in the whole year. It was the typical multi-hail zone in summer. The interannual variation of hail occurrence in Guyuan was big and had 3-year periodicity. The secondary-order time trend of hail in Guyuan was the anti-parabolic type, and the hail occurrence times during the 1960s-1980s presented the increase trend. It was the hail multi-occurrence period in the 1970s and 1980s. After the 1990s, the hail presented the decrease trend. In recent 20 years, the hail significantly decreased. The hail in Guyuan mainly concentrated during 12:00-21:00, and the hail occurrence times occupied 85% of total times. The hail distribution in Guyuan area had the obvious regional characteristics. The hail in the mountain area, hilly area was more and in the stream valley, north Pingchuan area was less. The hail cloud mainly derived from the mountain areas, such as Liupanshan, Nanhua Mountain, Yueliang Mountain, Xifeng Mountain and Yunwu Mountain, etc. The move direction of hail cloud was mainly from northwest to southeast or from north to south. Part of hail cloud disappeared in the original place. According to the regional distribution of hail, the hail risk in Guyuan City was divided into the high, moderate and low occurrence zones by combining with the hail disaster data. [Conclusion] The research provided the scientific basis for the forecast, early-warning of hail weather and the artificial hail suppression.

Analysis on Features of Hail and Hail Suppression in Hohhot in Recent 30 Years

Some characters of hail,such as its frequency,duration,diameter,disaster degree,were analyzed,based on the 1 375 pieces data of hails in Huhhot from1969 to 2000.Besides,3 000 pieces information about hail prevention from 1985 to 2000 was elaborated.The results showed that normally,the hail disaster lasts less than 5minutes,and its diameter is between 1 to 5 mm.Hail is more likely to happen from 16:00 pm to 17:00 pm.The practice of hail prevention effectively decreased hail disasters,and thus resulted in less damage.

Climatic Characteristics of Hail and Risk Zoning of Its Disaster Factor in Anhui Province

[ Objective] The research aimed to study climatic characteristics of hail and dsk zoning of its disaster factor in Anhui Province. [Method] Based on the hail-day records from 82 weather stations in Anhui Province, Chinese Meteorologica/Disaster Dictionary （1951 to 2005） and The Yearbook of Meteorological Disaster in Anhui Province （2006 to 2009）, we discussed the climatic characteristic and dsk zoning of hail disaster in Anhui Province. [Result] The hail days exhibited significant interdecadal variability, and it had a significant negative correlation with annual mean minimum temperature. The hail usually occurred from March to August, most frequently in June but less in autumn and winter. It most likely took place from aftemoon to sunset. The spatial distribution showed that the hail occurred more in northeast of Huaibei, south of Dabie Mountain and some areas of Huangshan Mountain, but less in Jianghuai region. The index of hail intensity was defined by three factors, the diameter, duration and gust grade, and the percentile method was used to grade the intensity of the hail disaster. This work provided a possibility for quantitative assessment of the intensity of hail disaster. The results of hail disaster risk zoning in Anhui Province showed that high dsk zones were concentrated in northeast of Huaibei, and low risk zones were mainly in south of Huaihe River. Finally, vedfied by historic disaster, it showed that the results of risk zoning had a certain rationality and feasibility. Conclusion The research could provide reference basis for hail disaster defense and assessment.