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1.
中国龙卷时空分布及其环境物理量特征 总被引：6，自引：2，他引：6
利用2004—2012年《中国气象灾害年鉴》和CFSR再分析资料,研究中国龙卷的时空分布以及三个龙卷频发区的环流背景场和环境物理量特征,并比较他们之间的区域差异。结果表明:中国龙卷多发生于春夏季,午后傍晚较多,江苏和广东等平原地区出现龙卷概率最高。龙卷临近时,“江苏及其邻近地区”位于500 hPa槽前,850 hPa上有西南急流,造成了较强的低层垂直风切变;“广东及其邻近地区”在龙卷发生前地面对流有效位能均值达997.3 J/kg,0~1 km螺旋度均值达91 m2/s2,层结不稳定,动力抬升强;“东北地区”受深厚东北冷涡控制,整层水汽含量低,中低层比湿均值小于10 g/kg。通过比较环境物理量平均场的分布特征发现:螺旋度、垂直风切变、能量螺旋度指数和强龙卷参数对分析龙卷发生有很好的指示意义。“东北地区”对流有效位能和比湿均值远低于“江苏及其邻近地区”和“广东及其邻近地区”,但高低空的温度直减率大、中低层的垂直风切变强,该地区也会产生龙卷。 相似文献
2.
利用常规观测、自动气象站、多普勒雷达等资料分析珠江三角洲台风龙卷的活动特征及其产生的环境条件。结果表明:台风龙卷发生在6—10月,时间多为10—20时,出现在台风登陆后1.3～21.3 h的时段内;多数龙卷位于台风中心的东北象限,台风中心在广东湛江一广西东南部或北部湾附近时是珠江三角洲龙卷发生的高风险期。高层辐散、低层辐合及中低空强东南急流在珠江口附近叠加是龙卷产生的有利环流背景。强或弱龙卷环境条件的共同特征为低抬升凝结高度、强深层和低层垂直风切变及较大风暴相对螺旋度(SRH),主要差异是强龙卷的深层和低层垂直风切变与SRH更大;相似台风路径下,有/无龙卷环境条件的明显差异在于0～1 km低层垂直风切变和SRH,两值越大出现超级单体或中气旋的可能性越大,龙卷发生概率也就越高。台风龙卷风暴母体属于低质心的微型超级单体风暴;低层有强或中等强度中气旋,有时强中气旋中心伴有龙卷涡旋特征(TVS);龙卷出现在钩状回波顶端或TVS附近。与西风带超级单体龙卷相比,台风龙卷中气旋的尺度更小、垂直伸展高度更低。 相似文献
3.
利用现场灾调资料、Micaps资料、地面加密自动站和广州SA雷达资料等，对2018年8月31日广州番禺龙卷天气过程进行分析。结果表明：该次龙卷发生在14:25前后，路径长度约80 m,最大破坏宽度约52 m,破坏等级为EF1级。龙卷发生在季风低压活动天气背景下，中低空西南急流的叠加交汇及低层辐合、高层辐散的配置为龙卷的发生提供了有利的天气尺度条件；较大的对流有效位能、深厚的湿层和极低的抬升凝结高度为龙卷的发生提供了充足的对流不稳定能量和水汽条件；较大的低空垂直风切变、较大的风暴相对螺旋度和较大的能量螺旋度，为超级单体风暴的发生提供了有利的动力条件，地面中尺度辐合线和小尺度涡旋是对流风暴触发的有利中小尺度系统；龙卷产生在微型超级单体风暴中，伴有弱中气旋，龙卷触地前后伴有风暴质心明显下降、中气旋强度增强和直径尺寸明显缩小等特征。 相似文献
4.
非超级单体龙卷风暴多普勒天气雷达产品特征及预警 总被引：6，自引：3，他引：3
利用济南和烟台多普勒天气雷达资料,结合环境物理量和天气实况,对发生在山东境内的6个非超级单体龙卷风暴特征进行了分析。6个非超级单体龙卷风暴产生于5次天气过程,其中4次过程属于后倾槽结构,1次是西北气流结构。6个非超级单体龙卷中EF0级龙卷2次,EF1级龙卷3次,EF2级龙卷1次。综合分析结果表明,低层大的湿度和0~1 km垂直风切变≥7 m·s~(-1)是非超级单体龙卷发生的有利条件。平均径向速度产品上,方位上相邻距离库之间速度差值超过20 m·s~(-1),或者,相对风暴平均径向速度产品上,方位上相邻距离库之间速度差值超过15 m·s~(-1),可预警龙卷。6次龙卷有4次发生在风暴单体迅猛发展的阶段,风暴顶在1个体扫时间内迅速增高。风暴单体迅猛发展需要强上升气流配合,强上升气流将低层辐合线上的小涡旋迅速拉伸,使得旋转运动进一步发展,诱发小尺度范围的强切变,从而导致龙卷发生。 相似文献
5.
通过台风登陆前的探空、多普勒雷达资料以及数值模拟,对0709号台风“圣帕”登陆前龙卷发生的环境背景、发生、发展和消亡的过程特点进行了分析。从周围环境场分析表明,龙卷发生地处于高的能量不稳定区并且具有非常低的抬升凝结高度和较强的低层垂直风切变,利于龙卷生成。雷达分析显示龙卷发生前存在弱的中气旋和低层气旋式切变,龙卷发生时伴随着这两个弱涡旋的合并增强,这可能是爆发龙卷的重要原因之一。数值模拟能较好地模拟出在龙卷发生时该区域有较强的风切变和水汽通量的辐合,并且螺旋度和风暴相对螺旋度有瞬时的强烈变化。 相似文献
6.
2018年8月19日受台风“温比亚”影响,山东省临沂市遭受龙卷袭击。通过实地灾情调查,给出了该龙卷的影响范围、灾害分布和强度评估等,综合考虑不同标识物和致灾过程,评估本次龙卷强度为EF3级。分析龙卷发生的环境和天气雷达特征,结果表明:龙卷发生在低抬升凝结高度（≤300 m）、强低层垂直风切变（≥18×10-3 s-1）、强相对风暴螺旋度（≥350 m2/s2）和较低对流有效位能（≤400 J/kg）的有利环境条件下;龙卷超级单体嵌于台风右侧螺旋雨带内,龙卷发生在中气旋与风暴后侧下沉气流区相接一侧,与龙卷涡旋特征位置对应;龙卷及地时中气旋向下延伸加强,同时风暴顶及单体质心迅速下降;若探测到低层中等强度中气旋时应发布龙卷预警,则此次过程的龙卷预警时间提前量为15~20 min。 相似文献
7.
利用高空、地面常规观测资料、分钟级加密自动气象站资料和榆林多普勒雷达资料,对 2013 年8月4日傍晚发生在榆林市的一次超级强对流风暴天气进行中尺度分析。结果表明：（1）此次过程疑似一次超级单体龙卷天气过程;（2）从环流背景来看,榆林市上空中层强干冷平流配合低层切变线、西南急流,高层干冷、低层暖湿特征明显;从环境条件来看,强风暴发生前和发生期间能量、抬升凝结高度、风切变满足龙卷发生所需的热力不稳定、垂直风切变条件;（3）雷达钩状回波结构清晰,并伴有强中气旋,大于60 dBZ的回波和正负速度对已接地,呈现龙卷发生时的回波特征;（4）强风暴发生前后,由北向南经过榆林地区有多个龙卷涡旋TVS产品被识别;（5）气象要素场变化剧烈,地面气压明显降低,风速出现极值增强,风向发生突变,与龙卷发生期间风场观测特征基本一致,表明该区域出现龙卷的可能性较大。 相似文献
8.
2018年9月17日09:37—10:00,在登陆台风“山竹”外围螺旋雨带中,广东省佛山市三水区到肇庆市四会区发生了EF2级强龙卷,龙卷路径长度18 km,持续时间23 min,平均时速47 km/h,导致不少建筑物损毁。本次过程佛山市进行了龙卷预警试验,提前37 min发布了龙卷预警,龙卷没有造成人员伤亡。利用观测资料对产生强龙卷的环境场特征、地面自动站和雷达观测的中小尺度特征以及龙卷预警试验进行了分析,结果表明:产生龙卷的微型超级单体出现在台风外围和副高边缘之间的强东南急流中,具有低层辐合、高层辐散、水汽充足等典型台风外围龙卷环流形势特征;强的低空0~1 km垂直风切变、大的风暴相对螺旋度和低的抬升凝结高度等环境条件利于龙卷的生成;龙卷影响时,邻近地面自动气象站观测要素表现出明显的信号,瞬时大风和最低气压的极值区呈东南至西北向带状分布,与龙卷路径一致,龙卷过境前后,单站气压“漏斗”明显,5 min降压/升压幅度达-2.5 hPa/+2.1 hPa;广州多普勒天气雷达探测到龙卷母体风暴的低层钩状回波和入流缺口特征,以及低层强中气旋和类TVS特征。预警试验初步表明,对台风龙卷高发区,在环境场有利情况下,若低层出现中等或以上强度中气旋,其底高在1 km以下,可以考虑发布龙卷预警。 相似文献
9.
利用逐日4次1°×1°FNL/NCEP分析资料及多普勒天气雷达、地面自动气象站等观测资料,在对近十年江苏梅雨期龙卷天气的环境特征进行合成分析并提炼对流参数特征值后,着重对2013年7月7日发生在安徽天长至江苏高邮一带导致龙卷的对流风暴的形成和结构特征演变进行了分析。结果表明:江淮梅雨期间,地面中尺度气旋的右侧附近(100 km)、对流层低层中尺度低涡右下方约200~300km处和低空急流左后侧之间区域是龙卷易发区;梅雨期大气环流背景为龙卷的发生提供了对流层低层充沛的水汽和有利的不稳定层结与动力条件,低层气旋性涡度在龙卷发生前强烈发展,边界层内强的垂直风切变促进了龙卷风暴内气旋性涡度的迅速增强,而对流层低层辐合的增强将有利于初始对流的触发;但梅雨期龙卷对对流不稳定能量蓄积条件要求低于冰雹和雷暴大风;龙卷对流参数特征值及其与气候平均值的差异性为龙卷天气的短期预报提供了参考依据。引发2013年7月7日龙卷的对流风暴起源于地面辐合线附近,地面辐合及中尺度锋区的增强有利于对流风暴的快速发展,此次系列龙卷是由一个生命史较长的超级单体风暴产生,该对流风暴具有典型超级单体的回波特征,风暴内的中气旋维持2h之久,中气旋相关参数的演变对龙卷的临近预警有较高的参考价值,当中气旋底高较低且中气旋切变值明显增强时,发生龙卷天气的可能性较大。 相似文献
10.
利用ECMWF高分辨率再分析资料及广州多普勒天气雷达资料,对1522号台风"彩虹"外围衍生的广州番禺龙卷和1806号台风"艾云尼"外围衍生的广州南沙龙卷进行对比分析,同时还挑选了一个未发生龙卷的台风做外围环境参数对比。结果表明:两次强龙卷都发生在登陆台风的东北象限,中低空急流明显、低层辐合、高层辐散在珠江三角洲地区叠加是产生龙卷的有利天气背景。环境影响因子均表现为对流有效位能较大、低层风速较大、垂直风切变较强、抬升凝结高低较低、抬升指数较小、风暴相对螺旋度较大:相比之下,未发生龙卷的台风外围中低空急流依然明显,但其他环境影响因子大多数未达到发生龙卷的条件阈值。雷达反射率上均表现为一些超级单体特征,最强反射率均在59 dBZ以上,且低仰角都存在明显的速度对。由于"彩虹"龙卷过程的对流有效位能、中低层风速、低层风切变、抬升指数及中气旋强度等环境影响因子均明显强于"艾云尼"龙卷过程,导致其强度明显强于"艾云尼"龙卷。 相似文献
11.
Observed daily precipitation data from the National Meteorological Observatory in Hainan province and daily data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis-2 dataset from 1981 to 2014 are used to analyze the relationship between Hainan extreme heavy rainfall processes in autumn (referred to as EHRPs) and 10–30 d low-frequency circulation. Based on the key low-frequency signals and the NCEP Climate Forecast System Version 2 (CFSv2) model forecasting products, a dynamical-statistical method is established for the extended-range forecast of EHRPs. The results suggest that EHRPs have a close relationship with the 10–30 d low-frequency oscillation of 850 hPa zonal wind over Hainan Island and to its north, and that they basically occur during the trough phase of the low-frequency oscillation of zonal wind. The latitudinal propagation of the low-frequency wave train in the middle-high latitudes and the meridional propagation of the low-frequency wave train along the coast of East Asia contribute to the ‘north high (cold), south low (warm)’ pattern near Hainan Island, which results in the zonal wind over Hainan Island and to its north reaching its trough, consequently leading to EHRPs. Considering the link between low-frequency circulation and EHRPs, a low-frequency wave train index (LWTI) is defined and adopted to forecast EHRPs by using NCEP CFSv2 forecasting products. EHRPs are predicted to occur during peak phases of LWTI with value larger than 1 for three or more consecutive forecast days. Hindcast experiments for EHRPs in 2015–2016 indicate that EHRPs can be predicted 8–24 d in advance, with an average period of validity of 16.7 d. 相似文献
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Based on the measurements obtained at 64 national meteorological stations in the Beijing–Tianjin–Hebei (BTH) region between 1970 and 2013, the potential evapotranspiration (ET0) in this region was estimated using the Penman–Monteith equation and its sensitivity to maximum temperature (Tmax), minimum temperature (Tmin), wind speed (Vw), net radiation (Rn) and water vapor pressure (Pwv) was analyzed, respectively. The results are shown as follows. (1) The climatic elements in the BTH region underwent significant changes in the study period. Vw and Rn decreased significantly, whereas Tmin, Tmax and Pwv increased considerably. (2) In the BTH region, ET0 also exhibited a significant decreasing trend, and the sensitivity of ET0 to the climatic elements exhibited seasonal characteristics. Of all the climatic elements, ET0 was most sensitive to Pwv in the fall and winter and Rn in the spring and summer. On the annual scale, ET0 was most sensitive to Pwv, followed by Rn, Vw, Tmax and Tmin. In addition, the sensitivity coefficient of ET0 with respect to Pwv had a negative value for all the areas, indicating that increases in Pwv can prevent ET0 from increasing. (3) The sensitivity of ET0 to Tmin and Tmax was significantly lower than its sensitivity to other climatic elements. However, increases in temperature can lead to changes in Pwv and Rn. The temperature should be considered the key intrinsic climatic element that has caused the "evaporation paradox" phenomenon in the BTH region. 相似文献
13.
Storms that occur at the Bay of Bengal (BoB) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the BoB are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the BoB storm activity, and the “bimodal period” of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the “bimodal pattern” storm activity in the BoB. The analysis on sea surface temperature (SST) shows that the SSTs of all the year around in the BoB area meet the conditions required for the generation of tropical cyclones (TCs). However, the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a “two-peak” storm activity pattern. The genesis potential index (GPI) quantifies and reflects the environmental conditions for the generation of the BoB storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms. 相似文献
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The spatial and temporal variations of daily maximum temperature(Tmax), daily minimum temperature(Tmin), daily maximum precipitation(Pmax) and daily maximum wind speed(WSmax) were examined in China using Mann-Kendall test and linear regression method. The results indicated that for China as a whole, Tmax, Tmin and Pmax had significant increasing trends at rates of 0.15℃ per decade, 0.45℃ per decade and 0.58 mm per decade,respectively, while WSmax had decreased significantly at 1.18 m·s~(-1) per decade during 1959—2014. In all regions of China, Tmin increased and WSmax decreased significantly. Spatially, Tmax increased significantly at most of the stations in South China(SC), northwestern North China(NC), northeastern Northeast China(NEC), eastern Northwest China(NWC) and eastern Southwest China(SWC), and the increasing trends were significant in NC, SC, NWC and SWC on the regional average. Tmin increased significantly at most of the stations in China, with notable increase in NEC, northern and southeastern NC and northwestern and eastern NWC. Pmax showed no significant trend at most of the stations in China, and on the regional average it decreased significantly in NC but increased in SC, NWC and the mid-lower Yangtze River valley(YR). WSmax decreased significantly at the vast majority of stations in China, with remarkable decrease in northern NC, northern and central YR, central and southern SC and in parts of central NEC and western NWC. With global climate change and rapidly economic development, China has become more vulnerable to climatic extremes and meteorological disasters, so more strategies of mitigation and/or adaptation of climatic extremes,such as environmentally-friendly and low-cost energy production systems and the enhancement of engineering defense measures are necessary for government and social publics. 相似文献
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《大气和海洋科学快报》2013,(1):67
正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome.SUBMISSIONAll submitted 相似文献
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<正>With the support of specialized funds for national science institutions,the Guangzhou Institute of Tropical and Marine Meteorology,China Meteorological Administration set up in October 2008 an experiment base for marine meteorology and a number of observation systems for the coastal boundary layer,air-sea flux,marine environmental elements,and basic meteorological elements at Bohe town,Maoming city,Guangdong province,in the northern part of the South China Sea. 相似文献
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《大气和海洋科学快报》2014,7(6):F0003-F0003
AIMS AND SCOPE
Atmospheric and Oceanic Science Letters （AOSL） publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome. 相似文献
Atmospheric and Oceanic Science Letters （AOSL） publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome. 相似文献
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《大气和海洋科学快报》2014,(5):F0003-F0003
AIMS AND SCOPE Atmospheric and Oceanic Science Letters （AOSL） pub- lishes short research letters on all disciplines of the atmos- phere sciences and physical oceanography. Contributions from all over the world are welcome. 相似文献
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《大气和海洋科学快报》2012,(3):273
正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences 相似文献