Analysis of Causes for An Unusual Cloudy-rainy Weather for Several Days in Autumn

Cloudy-rainy weather for several days in 2007 was featured with the longest duration and the most serious extent of injury since the time from which there was meteorology observation record in Shandong.The causes of this process were analyzed in this article in terms of general circulation,character of physical quantity and tropical cyclone.The result showed that the precipitation process was a long wave adjustment process and it took place during the transformation process of general circulation turning from the zonal to the radial.During the cloudy-rainy weather process,the Ural mountain ridge and the Western Pacific subtropical high were more abnormally strong and in the further north than that in any other years.The tropical cyclone in the south of the subtropical cyclone activity was more frequent.There was more shortwave in middle latitudes of Asian.The cold air masses Siberia went down south.The cold air masses joined with the current of air in the Lower Yellow River.This led to the lasting cloudy-rainy weather for several days in Shandong.

Effects of rainy weather on traffic accidents of a freeway using cellular automata model

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.

Analysis of Continuous Rainy and Cold Weather in Yiwu in Early Spring of 2009

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 Iow-prassure 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.

Irregular Information of the Rainstorm in a Continuous Rainy Weather

[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.

Variation Characteristics of Low Temperature and Rainy Weather in Guangxi during Spring Sowing Period of Recent 50 Years

[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.

Design and evaluation of UHPP steel bridge deck pavement for high-temperature and rainy regions

To enhance the serviceability of steel bridge deck pavement(SBDP)in high-temperature and rainy regions,a concept of rigid bottom and flexible top was summarized using engineering practices,which led to the proposal of a three-layer ultra-high-performance pavement(UHPP).The high-temperature rutting resistance and wet-weather skid resistance of UHPP were evaluated through composite structure tests.The internal temperature distribution within the pavement under typical high-temperature conditions was analyzed using a temperature field model.Additionally,a temperature-stress coupling model was employed to investigate the key load positions and stress response characteristics of the UHPP.The results indicate that compared with the traditional guss asphalt+stone mastic asphalt structure,the dynamic stability of the UHPP composite structure can be improved by up to 20.4%.Even under cyclic loading,UHPP still exhibits superior surface skid resistance compared to two traditional SBDPs.The thickness composition of UHPP significantly impacts its rutting resistance and skid resistance.UHPP exhibits relatively low tensile stress but higher shear stress levels,with the highest shear stress occurring between the UHPP and the steel plate.This suggests that the potential risk of damage for UHPP primarily lies within the interlayer of the pavement.Based on engineering examples,introducing interlayer gravel and optimizing the amount of bonding layer are advised to ensure that UHPP possesses sufficient interlayer shear resistance.

Analysis of a Rare Continuous Rainy Process in Midsummer

[Objective] The research aimed to analyze a rare low temperature and rainy weather process which happened in Anhui Province from July 22 to August 14,2009.[Method] Based on the data of conventional observation,NCEP analysis field and automatic station,a rare low temperature and rainy weather process which occurred in Anhui Province from July 22 to August 14,2009 was analyzed.The formation reason of continuous rainy process in midsummer was discussed.The circulation characteristics and influence systems of continuous rainy process were revealed.On the base,the influences of configuration of circulation fields and difference of physical quantity fields at high and low layers on range and intensity of precipitation were analyzed.[Result] According to the circulation situation and influence system,the continuous rainy process could be divided into four stages:July 22-24,from July 27 to August 1,August 4-8 and August 9-14.Moreover,it was respectively affected by northeast low vortex,cold and warm air,high-level low trough,typhoon and periphery of subtropical high at four stages.The maintenance of big specific humidity zone provided sufficient water vapor condition for the continuous rainy weather.The rainstorm appeared in dense zone of specific humidity line,where the specific humidity >13 g/kg in the humidity front zone.A temperature trough maintained at 850 hPa.The cold air which continued to diffuse and go south was main reason of the abnormally low temperature during the continuous rainy period.Moreover,it provided ascending motion condition for precipitation maintenance.[Conclusion] The research provided references for actual forecast of continuous rainy weather.

四川盆区油菜花期低温阴雨灾损评估及风险区划

花期低温阴雨是四川盆区油菜生产的主要气象灾害之一。本研究利用四川盆区1961-2020年101个气象站的逐日气象资料,1983-2000年油菜产量资料和干旱、低温冷害、连阴雨、大风、冰雹灾情资料,筛选花期低温阴雨灾害年份,采用数理统计方法获取花期低温阴雨产量灾损率和致灾因子,通过相关性分析确定油菜花期低温阴雨致灾指标,并利用2001-2020年灾情资料进行检验;基于筛选出的低温、连阴雨关键致灾因子,采用回归分析法建立油菜花期低温阴雨灾害损失评估模型,并进行回代和预测检验,分析灾害风险区划和变化趋势。结果表明:(1)日平均气温≤7℃、过程持续天数≥1d是四川盆区油菜花期低温致灾指标,日平均气温≤7℃的负积温和≥3d过程持续降水量共同组成低温阴雨灾害的关键致灾因子;选用2001-2020年油菜花期低温冷害发生情况对指标进行检验,与实际情况相符。(2)选用1983-2000年的气象、产量、灾情数据建立四川盆区油菜花期低温阴雨灾损评估模型,模型对轻度、中度灾害损失评估等级与实际等级相同或相差1级的评估准确率在96%以上;重度、特重评估等级与实际等级相同的准确率为0,与实际等级相差1级的准确率为75%和0。选用2001-2020年油菜花期低温阴雨灾害发生情况对模型检验,与实际情况基本相符。(3)1961-2020年四川盆区油菜花期低温阴雨灾害风险偏高区域主要分布于盆区西南部、南部及东北部,以中-高风险为主;灾害风险偏低的区域集中于盆区西北部及中部,以低-次低风险为主。(4)气候变暖背景下,四川盆区油菜花期低温阴雨灾害高风险区域呈减少趋势,低风险区域呈增加趋势。综上分析,四川盆区油菜花期低温冷害指标结果可靠,低温阴雨灾损评估模型能够较好地评估灾害损失,可应用于农业气象业务服务;灾害风险区划结果可为四川油菜生产布局提供参考依据。

2023年河南麦收连阴雨的形成和环流异常分析

2023年5月25—30日河南遭遇了1961年以来同期持续时间最长、影响最大的连阴雨天气过程。连阴雨天气导致小麦大幅减产,品质下降,豫南、豫中和豫东部分种子田失去种用价值,被评为“烂场雨”。利用常规观测资料、NCEP再分析资料和EC数值预报产品,对这次连阴雨过程的大尺度环流形势和影响系统进行分析。结果表明:(1)该天气过程发生在异常大气环流背景下,西太平洋副热带高压显著偏强,脊线5天滑动平均位置偏北达8个纬度,越过25°N线;西伯利亚高压也显著偏强且频繁向南暴发。(2)乌拉尔山阻塞系统的形成导致我国新疆西北部长时间维持一深厚冷涡,从而在35°—40°N形成了稳定纬向环流,冷涡底部不断有冷空气分裂东移南下影响河南。远距离超强台风的逼近导致副热带高压迅速西伸北抬,在其外围形成了一条宽广、深厚的从南海伸向中纬度地区的暖湿气流输送带,最终在豫西北汇聚出低空急流。随着暖湿气流输送带向北扩展,在大风速区的前方,对流层中低部有明显的空气质量和水汽的辐合,从而引发上升运动的发生发展,导致多地暴雨、局部大暴雨的出现。(3)南北两个异常的天气系统的结合,促成了中纬度能量锋区的稳定维持,锋面抬升对暖区降水起到增幅和维持作用。(4)数值模式对中、短期环流趋势和影响系统均作出了较准确的预报,但对降水量级及其分布的预测还需要进一步推敲订正。

2023年江苏省麦收期连阴雨天气特征及其对冬小麦的影响分析

基于自动气象站观测资料、ECMWF再分析资料、江苏省冬小麦生育期及产量资料,对2023年5月下旬大范围连阴雨过程的成因进行研究,分析了天气过程和大气环流背景特征,以及连阴雨对江苏省冬小麦成熟和收获进度等的影响。结果表明:(1)本次过程具有降水日数多、范围广、雨量大、短时强降水特征明显、伴有高温天气出现及日照时数少等特点,5月26—31日江苏省雨量较常年同期偏多2~4倍,降水日数较常年同期偏多4成,长江以北累计日照时数较常年同期偏少5~8成。(2)500 hPa上,与历史同期相比,乌拉尔山脉附近高压与贝加尔湖附近低槽强度偏大40~60 gpm,副热带高压偏强偏北约5个纬度;850 hPa上,副热带高压边缘的西南气流与“玛娃”台风外围云系提供了有利的水汽输送条件,多系统共同作用下造成了此次连阴雨过程的极端性。(3)持续阴雨寡照,不利于作物光合作用,造成江苏省冬小麦收获期较2008—2022年推迟2~3天、淮北局部麦田发生“穗发芽”现象。淮北地区冬小麦受影响程度总体大于苏南地区,徐州市2023年冬小麦千粒重较2022年的减少3.94 g,这主要与生育期、作物品种、连阴雨强度有关。近16年来江苏省麦收平均受连阴雨影响的频次为3.2年/次,适时早播,成熟收获期适时提前收割,育种方面突出培育早熟或抗穗发芽的小麦品种,可以避免麦收期间连阴雨灾害影响,减少或避免粮食损失。

山区公路线形及天气对驾驶人生理及行为特性影响

目的探究山区公路线形与天气条件对不同熟练度驾驶人生理及行为特性的耦合影响。方法通过开展实车试验,采集20名驾驶人在山区公路驾驶过程中的生理及行为特性数据,以心率增长率和瞳孔面积变化率为生理指标,以速度均值和标准差为行为指标,分析不同熟练度驾驶人在山区公路不同线性及天气条件下的驾驶负荷变化规律,使用熵权TOPSIS法对驾驶负荷进行量化评价。结果降雨量、线形条件和熟练度对驾驶人生理变化和速度控制具有显著影响;此外,降雨和线形耦合作用下的驾驶负荷变化显著,非熟练驾驶人、大雨/中雨和回头曲线场景下的驾驶负荷相对较高,相对接近度均高于0.5。结论驾驶负荷与降雨量呈正相关关系,与熟练度呈负相关关系,回头曲线路段驾驶负荷高于直线段,研究结果可为山区公路安全预警防控及安全配套设施设置提供参考。

多雨天气对大樱桃的不良影响及应对措施

近3年间,陕西省商洛市大面积结果期大樱桃由于遭受多雨天气的不良影响,致使果农正常生产经营活动受限,从而导致相关病虫危害加重、落花落果、缩果、大量裂果及树体生长不良等弊端。该文从不同角度剖析了这些危害的发生原因、过程及对大樱桃生产经营活动的影响程度和造成的经济损失,通过有关技术措施的应用,提出相应的应对措施。供广大果农参考。

太行山区连翘雨季直播造林技术研究

在太行山区开展了连翘雨季直播造林试验,通过出苗率、越冬越夏存活率、留苗率、生长量等指标的测定,探讨连翘在无灌溉条件下的种植方法,包括种子处理、保水剂应用、雨季播种时机选择、造林地选择、有无地面覆盖物等。结果表明,在7月4日、7月9日、7月13日、7月20日,将经包衣剂或保水剂处理的种子播种于半阴坡、半阳坡或阳坡上,其出苗率、留苗率和生长量显著高于对照(CK)和其他处理;6月下旬进行直播,由于降水量相对少、雨期间隔时间久,不利于种子萌发。7月下旬至8月降水量充足,此时播种持续降雨会使种子被冲失,同时高温易抑制种子萌发。9月初播种幼苗生长期短,越冬难度大,留存率逐渐下降;在土层厚度≥12.5 cm,有地面覆盖物的阴坡、半阴坡,连翘幼苗越夏越冬存活率均在80%左右,株高在90.81 cm以上。故认为连翘在无灌溉条件下雨季直播造林,最适宜时期为7月上中旬,且在土层厚度大于12.5 cm的半阴坡或有植被覆盖的阳坡直播造林较好。

冷型小麦对干旱和阴雨的双重适应性

通过 10余年的研究 ,发现冠层温度持续偏低的冷型小麦具有广幅生态适应性 ,即在正常天气条件下 ,它的活力较好、代谢功能较强、具有较好的抗早衰能力 ,优于其它类型小麦 ;而在气象要素反差很大的干旱和连阴雨天气下 ,冷型小麦和暖型小麦、中间型小麦相比 ,不但冠层温度依然持续偏低 ,且在叶片功能期、叶绿素含量、可溶性蛋白质含量、过氧化氢酶活性、净光合速率和籽粒饱满指数等一系列重要内、外性状上仍能继续保持优势。这种对干旱和阴雨条件的双重适应性是冷型小麦一种宝贵的生物学品质 ,它有可能为小麦在多种气象生态条件下的高产、稳产打下较为坚实的生态生理基础 ,并能为优良品种的选育提出一个把冷温特征作为重要内容的较为新鲜的育种目标。

2008年初中国南方低温雨雪冰冻天气的季节内振荡特征

利用中国气象局国家气象中心750站逐日平均气温和降水资料、NCEP/NCAR再分析的逐日风场和近地面气温资料、以及NOAA逐日向外长波辐射资料,分析了2008年1月我国南方发生的低温冰冻雨雪天气异常。结果表明,这次冰雪灾害伴有异常的季节内振荡特征,整个过程共包括4次降温、降水过程,这4次降温过程都在近地面气温30~60天振荡的负位相控制下,而10~20天振荡的同位相叠加使第一、三次过程的降温更加明显。冰雪灾害前期（第一、二次过程）我国南方主要受由北向南传播的两种尺度（30~60天、10~20天）近地面气温季节内振荡的共同影响,以剧烈的降温天气为主;后期（第三、四次过程）主要受近地面气温和风场30~60天振荡的影响导致持续低温,同时伴有明显的降水,造成了严重的雨雪冰冻灾害。此外,热带季节内振荡（MJO）的活动对这次低温冰冻雨雪也有一定的影响,冰雪灾害前期赤道东印度洋到孟加拉湾一带MJO对流活动受抑制,西南风和水汽输送不足,没有为我国南方带来明显的降水;后期赤道东印度洋MJO对流异常活跃,对流层低层有暖湿空气流入我国南方,配合近地面冷空气的持续影响产生大范围的低温冰冻雨雪灾害。

2012年上半年我国南方地区极端阴雨天气评价——以湖南省为例

基于湖南省97个地面气象观测站观测资料,根据所选定的阴雨天气评价指标,运用数理统计方法,对2012年上半年湖南省阴雨天气特征及强度进行分析评估,结果表明,阴雨天气阶段性特征显著,属隆冬至初春历史罕见的寡照低温多雨事件与初春至初夏的极端多雨寡照事件的组合。同时根据社会调查数据对阴雨天气的影响展开多方位分析,得出低温阴雨天气不仅对农业造成了重大影响,而且对水利、交通、建筑业等多行业和人们身体健康也有较大影响,以此提出了应对极端天气气候事件的对策建议。

广东低温阴雨的低频振荡及环流特征

为了做好广东2—3月低温阴雨的中期与延伸期预报,该文分析了1953—2011年广州低温阴雨年景变化与广东低温阴雨年景变化的关系,并采用小波分析、相关分析等方法探讨了12月次年4月广州逐日气温的低频振荡及与低温阴雨的关系。结果表明:广州低温阴雨的年景变化与广东年景一致的相同率达94.9%(56/59)。轻度低温阴雨年份,12月—次年4月广州逐日气温主要存在8.0～18.3 d显著周期,而中等及严重年份主要存在10.1～28,4 d及30～89.6 d的振荡。2—3月长低温阴雨主要与18 d以上的周期振荡有关,尤其与45 d以上的季节内振荡强度变化密切相关。利用典型个例的合成分析,建立了长低温阴雨30～64 d季节内振荡的天气概念模型,它们反映了长低温阴雨回暖—降温—开始—维持—结束的大气环流演变特征,其中乌拉尔山—贝加尔湖以西的阻塞高压可作为广东出现长低温阴雨的500 hPa前兆信号。

2008年初我国南方雨雪低温天气的中期过程分析--Ⅲ：青藏高原-孟加拉湾气压槽

针对2008年1月24日～2月2日我国南方地区雨雪低温过程,分析了其中期演变特征及其可能机理。在亚非副热带地区,Rossby波能量从北非东北侧传播到东亚地区,引起青藏高原附近气压槽的加深和西太平洋副热带高压的加强及北扩,并与亚洲北部的高压脊配合,造成了这次较长时间的雨雪低温过程。东北大西洋和西欧的反气旋式异常环流为亚非副热带急流Rossby波与欧亚高纬度Rossby波活动的主要波源区。在对流层上层,贝加尔湖一带的高压脊在过程之前已形成,而在这次过程中缓慢减弱,来自上游Rossby波能量主要起抵消摩擦耗散的作用。西太平洋副热带高压在偏北位置上维持主要由来自青藏高原和孟加拉湾地区Ross-by波能量的注入所致。亚洲冷高压系统的强度、位置及形态决定了这次我国南方地区低温过程的重要特性。

广东省春季低温阴雨的年景变化趋势分析

利用广州２～３月１９０８～１９９７年平均气温与１９５１～１９９７年平均日照资料，用小波变换分析广东省低温阴雨的年景趋势变化，着重分析重低温阴雨年在小波系数图中的分布特征，并根据分析结果对未来１～２年的低温阴雨年景进行了预测估计；然后利用小波方差图确定２～３月平均气温存在４０年、６年左右周期振荡，日照存在４３年左右的周期振荡；最后分析了低温阴雨的年景变化与同期和前期５００ｈＰａ环流场及海温场分布特征的关系，得出了预测广东省低温阴雨年景趋势的一些有用信息。

高温多雨条件下沥青混合料水损害模拟研究

通过室内外模拟试验,研究了夏季高温多雨条件下沥青路面的水稳定性,并提出了以劈裂抗拉强度指标评价夏季室外水浴高温循环变化对沥青混合料水损害影响的方法.试验结果表明:在夏季高温多雨条件下,沥青路面浸水1个月,可导致其水稳定性降低60%左右;在饱水条件下,荷载和高温的循环作用加剧了沥青混合料的水损害.