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1.
《云南地理环境研究》2020,(2)
利用高空常规气象观测资料、NCEP/NCAR逐6 h 2.5°×2.5°再分析资料、葵花-8红外云图、自动气象站观测数据,对2019年1月7～9日孟加拉湾热带风暴"帕布"影响云南省期间造成红河州暴雨天气过程的大气环流背景、水汽条件、动力条件、大气不稳定层结等进行分析。结果表明:这是一次由孟加拉湾风暴远距离影响造成的冬季大暴雨天气事件;南支槽前的西南气流能把孟加拉湾风暴产生的云和水汽输送到云南省红河州上空;700 hPa西南低空急流为此次天气过程提供了充沛的水汽供应;高低空急流耦合为水汽的垂直输送提供了良好的动力抬升条件;地形作用和对称不稳定是造成此次冬季暴雨天气过程的触发机制。 相似文献
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应用M ICAPS常规资料,从环流背景和物理量场,对孟加拉湾风暴造成红河州不同降水的2007年5月16~18日和2008年5月3~5日的两次降水过程进行对比分析。对比分析得出:两次降水过程均受到孟湾风暴、冷空气、切变线的影响,孟湾风暴的强弱、水汽输送、副高是否西伸、中低层的对流是造成红河州不同降雨强度的主要原因。 相似文献
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利用MICAPS系统提供的大量天气实况和降雨实况,对云南省文山州2007年初夏第一场透雨的主要影响系统、水汽条件及动力条件进行分析,并对本次过程的雷达回波资料作简单的定量分析。发现云南文山一直处于副高外围的西南气流中,中低层切变南压过程中,一直维持在孟加拉湾一带的孟湾风暴沿着副高外围源源不断地输送水汽,这两者的密切配合,是这次持续强降水天气产生的主要因素。雷达回波图上也直观地显示了系统的移动路径及移动过程。 相似文献
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《云南地理环境研究》2017,(1)
利用NCEP 1°×1°资料和实况观测资料,针对2013年冬季云南4次降雪过程,使用诊断和对比的方法,分析研究4次降雪过程在形成机理等方面的异同点。研究发现:4次降雪中南支槽型降雪强度和范围明显强于无南支槽型;700 hPa上高度场北高南低型和锋区密集型为主要环流形势;南支槽前的西南暖湿气流与北方冷空气的交汇,会导致降水的明显加强。4次降雪过程云南西侧都有充沛的水汽输送,水汽通量增大是云南降雪的必备条件,降雪落区在辐合中心的偏东、偏北一侧、θ_(se)线陡立区附近及暖湿不稳定区域和高空急流入口右侧与地面锋区垂直环流相耦合的区域。强大的地面冷高压南压和地面冷空气的参与,能够为降雪提供有利的温度条件,更有利于降雪天气的产生和维持。 相似文献
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《云南地理环境研究》2018,(4)
通过对云南2次强寒潮过程进行对比分析,结果表明:横槽型和北脊南槽型是2次过程的主要中高纬环流形势;横槽型造成的降温范围更广,强度更强,持续时间更强,但降雪除了很大程度受制于冷空气外,还受到水汽和动力抬升条件的影响;北脊南槽型冷空气相对横槽型弱一些,但当配合强盛的南支槽,高原切变线,及高低空急流耦合作用下导致了暴雨强降雪天气; 2次强降雪过程云南西侧都有充沛的水汽输送,水汽通量的增大是云南强降雪的必备条件;中低层来自孟加拉湾的暖湿气流在云南南部形成能量积集区和强烈的水汽辐合区,在低层辐合、中高层辐散的耦合作用下,形成强烈的对流上升运动,为强降雨提供了动力和水汽条件;雨转雪相态变化过程中当地面出现"冷垫"一般指示降雪的出现。 相似文献
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采用合成平均分析方法,对2011年7月中旬江淮流域持续降水过程和11~13日大暴雨的大尺度环流和物理量进行了诊断,分析表明:(1)持续降水过程大尺度环流是不典型的双阻型,西脊在乌拉尔山以西地区,东脊在雅库茨克。副热带高压位置偏东脊线偏北。贝加尔湖东南方的低槽从蒙古经河套伸向华南,江淮流域处于槽前稳定的西南气流中。巴尔喀什湖低槽的加深东移及其底部不断分裂的短波槽,造成了持续降水期间的大暴雨过程。(2)江淮流域位于高空西南急流入口区右侧,低空风速大值带左侧。水汽主要来自孟加拉湾、南海和西太平洋地区,高低空的强烈辐散辐合所造成的深厚上升运动为暴雨提供了动力条件,对称不稳定为暴雨提供了不稳定机制。 相似文献
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中天山北坡春季寒潮型暴雪致灾成因分析 总被引：1，自引：0，他引：1
采用NCEP逐日4次1°×1°再分析资料和Micaps常规观测等资料,对2011年4月发生在中天山北坡乌鲁木齐地区寒潮型暴雪过程的致灾天气学成因进行综合分析,着重讨论了强降雪发生所具备的水汽条件、高低空急流等动力耦合机制及温度平流条件。结果表明:在稳定的环流背景下,春季500 h Pa西西伯利亚低槽位置南伸至35°N,使得冷暖空气活跃交绥造成中低层大气斜压性增强,加之天山准静止锋的长时间停滞维持,致使中天山北坡受强锋区的控制而形成持续性雨雪天气。深厚的湿层和持续的水汽辐合为暴雪的产生提供了丰沛的水汽条件;高低空急流配置及正涡度大值区由低层向对流层中层发展,有利于高层气流抽吸辐散、中低层暖湿气流辐合和上升运动的增强,为强降雪天气提供了动力条件;强降雪落区与湿位涡有较好的对应关系。冷暖平流稳定对峙加之低层冷平流侵入之强是造成暴雪持续、增幅和剧烈降温的重要原因之一。 相似文献
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利用1961—2019年降雪期乌鲁木齐市5个国家气象站日降水资料、NCEP逐日4次0.25°×0.25°和1°×1°再分析资料,统计分析乌鲁木齐市暴雪特征及大尺度环流形势,归纳出现暴雪的3种典型环流类型,并分别选取典型个例进行诊断和对比分析。结果表明：（1）乌鲁木齐市暴雪发生频率以0.3次·（10a）-1趋势上升,具有准20 a振荡周期,发生次数最多为3月（40%）,11月次之（32%）。（2）乌鲁木齐市暴雪分为槽前西南气流型、高空槽东移型和强锋区型,强锋区型比例最高但降雪量小,槽前西南气流型持续时间长且降雪量最大,高空槽东移型最少但影响面积更大且雪强更强。（3）乌鲁木齐市暴雪的主要影响系统为300 hPa极锋急流、500 hPa偏西或西南气流、700 hPa低空偏北急流和850 hPa西北气流。（4）形成乌鲁木齐市暴雪的机制为低层偏北气流遇山堆积迫使暖湿空气抬升形成“冷垫”,并与500 hPa以上西南气流形成强垂直风切变和深厚的锋生区,但因三类过程强锋生维持时间和锋面斜率与伸展高度的不同使产生暴雪的原因有明显差异。（5）暴雪的水汽输送主要为西南、偏西和西北路径,... 相似文献
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应用MICAPS常规资料结合FY-2卫星云图,通过天气分析与物理量诊断分析方法,对红河州2007年5月16～18日的持续性强降水天气过程进行了分析。这次过程主要影响天气系统为初夏孟加拉湾风暴、700 hPa切变线及地面冷锋,冷空气侵入孟加拉湾风暴外围环流导致强降水发展并持续。冷锋切变南下有利于水汽凝结量的增加及强降水天气发生发展环境的形成。孟加拉湾风暴带来的充沛水汽输送和强烈的上升运动与不稳定大气为持续强降水发生发展提供了有利条件。卫星云图上强对流云团覆盖区与红河州强降水区相对应。 相似文献
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我国西南地区2009年秋季特大旱灾大气环流特征分析 总被引：2，自引：0，他引：2
利用西南地区5省市126个气象站1961―2009年逐月降水资料以及NCEP/NCAR月平均资料,分析了西南地区2009年秋季特大旱灾降水变化特征以及同期的环流特征。结果显示:(1)2009年秋季,来自孟加拉湾地区、南海地区暖湿水汽与来自内蒙古水汽均减弱;西南地区大部分地区水汽净获得减少或者由水汽净获得转换为水汽净失去。(2)2009年9―10月份西风带纬向环流较往年增强,西风槽偏东,东亚大槽西翼偏北;11月份西风带经向环流较强,但内蒙古西部、宁夏、甘肃、青海东部南下偏北风经向分量较往年减弱,西风槽偏北。(3)2009年9月份副高偏西偏强,西南在副高控制下,辐合上升水汽减少;10月份云南、贵州、广西大部分地区受控副高;11月份副高西伸至孟加拉湾地区,偏南风只存在17.5°N以北的孟加拉湾地区,这削弱了孟加拉湾地区向我国西南地区输送的水汽量。 相似文献
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利用1951～2009年沾益测站的降水资料以及NCEP/NCARR的月平均气象场再分析资料分析了2009～2010年曲靖严重干旱天气成因。采用Z指数对曲靖秋冬春连旱异常年份进行划分,表明2009年是夏秋冬连旱最严重的年份。并通过分析曲靖历史上夏秋冬降水偏少年和偏多年的500 hPa高度距平场差值场来为2009年严重的连旱天气提供成因分析,认为:冷空气和偏南气流异常是造成曲靖降水正负异常的成因。2009年夏秋冬季环流与历史上旱年同期的中高纬槽脊强弱分布形势并不一致。从夏季到冬季,贝加尔湖附近位势高度经历了从偏高到异常偏低的变化,孟加拉湾到西太平洋的环流场位势高度持续性异常偏高,暖湿气流缺乏,即使北方有冷空气南下,由于云南下沉运动较常年明显偏强,冷空气也无法与水汽汇合,水汽输送少是产生持续气象干旱的关键原因。 相似文献
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During February 1992, a series of relatively warm storms passed eastward across southern California, yielding intense precipitation that triggered widespread mass movement, flooding, property damage, and loss of life. These storms were triggered by an intense low pressure system (976 mb) off northern California which deepened as its eastward progress was initially blocked by a high pressure ridge (1040 mb) across western North America. Between February 10 and 13, large areas of Ventura and Los Angeles counties experienced cumulative precipitation of 200–400 mm with intensities reaching 40–50 mm hr-1. Mass movement, mainly as soil slips that transformed downslope into debris flows, occurred where cumulative precipitation exceeded 300 mm and when sustained intensities exceeded 25 mm hr-1. Stream response was rapid, particularly in urban areas where impermeable surfaces and storm drains fed concrete stream channels. The canalized upper Los Angeles River and Arroyo Simi exceeded all previous discharges for over 43 and 36 years of record, respectively. Other streams, from the large Santa Clara River to modest Malibu Creek, yielded recurrence intervals for the peak discharge of between 8 and 24 years, but the rapidity of flooding everywhere was remarkable. Whereas main trunk streams, canalized or not, responded predictably, the storm series emphasized the problems of poorly controlled development of potentially unstable hillsides and floodable lowlands and indicated a need to reassess the assumptions upon which such development is permitted. [Key words: climatology, cyclonic storm, geomorphology, mass movement, flooding, California]. 相似文献
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A synoptic-scale climatology of precipitation amounts from thunderstorms was developed by analysis of amounts from individual storms for 220 stations in the conterminous United States for the period 1948-1977. The probability of having a thunderstorm without rainfall was assessed for each station. For storms which did produce precipitation, the probability distribution of amounts was found to be well summarized by the incomplete gamma distribution. Sets of seasonal maps of the probability of receiving any measurable amount, less than 4 mm, and more than 20 mm of precipitation are presented. Consistent spatial patterns are found. Thunder without precipitation is most likely in the west. The greatest probability of heavy precipitation occurs along the Gulf Coast, extending in the summer throughout the mid-section of the nation. Topographic effects are apparent, with mountainous areas generally having less intense precipitation than surrounding regions. [Key World: thunderstorms, precipitation probabilities, gamma distribution.] 相似文献
15.
Based on the sand dust storms data and climatic data in 12 meteorological stations around sand dust storm originating areas of the Taklimakan Desert, we analyzed the trends of the number of dust storm days from 1960 to 2005 as well as their correlations with temperature, precipitation, wind speed and the number of days with mean wind speed ≥ 5 m/s. The results show that the frequency of dust storm events in the Taklimakan region decreased with the elapse of time. Except Ruoqiang and Minfeng, in the other 10 meteorological stations, the frequency of dust storm events reduces, and in 4 meteorological stations of Kuqa, Korla, Kalpin and Hotan, the frequency of dust storm events distinctly decreases. The temperature has an increasing trend, while the average wind speed and the number of days with mean wind speed ≥ 5 m/s have decreasing trends. The correlation analysis between the number of days of dust storms and climatic parameters demonstrates that wind speed and the number of days with mean wind speed ≥ 5 m/s have strong positive correlation with the number of days of dust storms, with the correlations coefficients being 0.743 and 0.720 (p<0.01), respectively, which indicates that strong wind is the direct factor resulting in sand dust storms. Whereas precipitation has significant negative correlation with the number of days of dust storms (p<0.01), and the prior annual precipitation has also negative correlation, which indicates that the prior precipitation restrains the occurrence of sand dust storms, but this restraining action is weaker than the same year’s precipitation. Temperature has negative correlation with the number of dust storm days, with a correlations coefficient of –0.433 (p<0.01), which means that temperature change also has impacts on the occurrence of dust storm events in the Taklimakan region. 相似文献
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本文通过对1963—1987年北京城、郊区测点的降水和相对湿度资料的对比分析,发现北京城区夏、秋季存在“干岛”现象,而冬、春季却存在明显的“湿岛”现象。城区四季都存在雨岛,雨岛现象夏季最明显。 相似文献
18.
湖南降水变化及与印度降水关系研究 总被引：2，自引：0，他引：2
基于湖南和印度的降水资料,采用回归分析、相关系数和小波分析方法研究了近46 a来湖南降水变化趋势、湖南与印度降水关系以及湖南年降水的周期。结果表明:(1)湖南年降水微弱增加,存在4个特征时间尺度,分别为3 a左右、7 a、11 a以及22 a左右。同时发现年降水以22 a左右尺度上的周期振荡为主。(2)湖南冬夏降水显著增加,春秋降水微弱减少。值得注意的是夏季降水增加而降水日数却在减少,这导致了暴雨发生概率的加大。(3)湖南与印度降水关系较好。如同期,湖南与印度东北区降水关系最为密切,自春到冬,两者相关程度逐渐加大。降水的上述变化趋势致使湖南洪涝、旱灾和暴雨事件频发,严重影响着人们的生产与生活。 相似文献
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Based on the sand dust storms data and climatic data in 12 meteorological stations around sand dust storm originating areas of the Taklimakan Desert, we analyzed the trends of the number of dust storm days from 1960 to 2005 as well as their correlations with temperature, precipitation, wind speed and the number of days with mean wind speed 〉 5 m/s. The results show that the frequency of dust storm events in the Taklimakan region decreased with the elapse of time. Except Ruoqiang and Minfeng, in the other 10 meteorological stations, the frequency of dust storm events reduces, and in 4 meteorological stations of Kuqa, Korla, Kalpin and Hotan, the frequency of dust storm events distinctly decreases. The temperature has an increasing trend, while the average wind speed and the number of days with mean wind speed ≥ 5 m/s have decreasing trends. The correlation analysis between the number of days of dust storms and climatic parameters demonstrates that wind speed and the number of days with mean wind speed 〉 5 m/s have strong positive correlation with the number of days of dust storms, with the correlations coefficients being 0.743 and 0.720 （p〈0.01）, respectively, which indicates that strong wind is the direct factor resulting in sand dust storms. Whereas precipitation has significant negative correlation with the number of days of dust storms （p〈0.01）, and the prior annual precipitation has also negative correlation, which indicates that the prior precipitation restrains the occurrence of sand dust storms, but this restraining action is weaker than the same year＇s precipitation. Temperature has negative correlation with the number of dust storm days, with a correlations coefficient of -0.433 （p〈0.01）, which means that temperature change also has impacts on the occurrence of dust storm events in the Taklimakan region. 相似文献
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ABSTRACT. Historically, storm tides wreaked havoc in the Bay of Fundy. With the tidal system resonating at close to the 12-hour, 25-minute dominant lunar tide of the Atlantic Ocean, variations in normal Fundy tides are in the main caused by astronomical factors. The strongest Fundy tides occur when the three elements—anomalistic, synodical, and tropical monthly cycles—peak simultaneously. The closest match occurs at intervals of 18.03 years, a time known as the Saros. Problems arise when storms coincide with these intervals. A strong Saros has coincided with several major historical storm tides in the Bay of Fundy, including the 1976 Groundhog Day storm, the 1869 Saxby Tide, and the 1759 storm tide. With continuing global sea-level rise and regional crustal subsidence, the possible recurrence of destructive storm tides has grave implications for property owners and settlements in the Fundy coastal zone. 相似文献