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1.
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
2.
不稳定能量参数在一次强对流天气数值模拟中的应用 总被引：5，自引：0，他引：5
采用常规观测资料和1°×1°NCEP／NCAP再分析资料,运用MM5V3．7高分辨率中尺度数值模式,对2004年7月12日17时30分前后发生在江苏南通的一次强中尺度对流系统（龙卷）进行模拟分析。结果表明：南通上空处在上干冷、下暖湿的大气不稳定层结中。干冷空气侵入与边界层暖湿气流强烈辐合,大量能量释放造成了本次龙卷的发生。运用数值模拟结果,计算了最佳对流有效位能IBCAPE、对流抑制能量ICIN、归一化对流有效位能INCAPE、能量—螺旋度指数,刚和强对流天气威胁指数／SWEAT等不稳定能量参数。通过分析上述参数的空间分布和在南通上空的时间分布,发现它们对强对流天气的发生有一定反映。 相似文献
3.
利用常规气象资料、NCEP FNL 1°×1°再分析资料以及卫星雷达资料，对2019年6月17日发生在张家口的一次与线状对流伴随的龙卷天气进行分析。结果表明：（1）龙卷天气发生在对流层中低层高能中心、强垂直风切变以及中层强风速区的环境中。（2）中低层强的正水平螺旋度、低层强辐合与高层强辐散配置为龙卷发生提供了有利的环境条件。（3）在对流不稳定区，边界层辐合线是对流的触发条件，弧状云线的发展加强和上冲云顶的识别分析有利于判断对流云团的发展趋势，对强对流的短临预警有重要参考意义。（4）通过雷达资料与风场反演分析，线状对流中的龙卷是由γ中尺度涡旋在低层强辐合与上升气流的拉伸下形成的。强辐合区主要位于3 km高度以下。 相似文献
4.
本文应用逐时地面和台风加密观测资料及常规资料,对89.9大范围台前龙卷天气的形成作了较为详细的分析。结果表明;(1)龙卷天气三个峰值期和集中区的出现与地面中尺度切变线和中低压有密切联系;(2)切变线和申低压位于暖脊附近,切变线和中低压的附近各有一个较强的辐合中心与之配合;(3)龙卷的发生与中尺度辐合中心和1小时强降水中心的活动密切相关;(4)龙卷的发生区、强度和中尺度辐合中心,地面ΔP_1负中心的位置和强度相对应;(5)中层的强风和低湿以及空气的潮湿不稳定也是龙卷形成和发生的重要原因之一。 相似文献
5.
利用常规地面和探空资料、珠海S波段双偏振多普勒天气雷达和珠海横琴X波段相控阵雷达资料对2021年6月1日发生在珠江口的水龙卷过程进行分析。研究表明:此次水龙卷过程发生在高层强辐散、中层短波槽影响、低层西南风的背景场下;极低的抬升凝结高度、较大的0~1 km风矢量差、超过超级单体发生阈值的风暴相对螺旋度,为龙卷的发生提供了较好的动力条件。两部雷达均观测到超级单体结构特征,最强反射率因子超过65 dBZ。X波段相控阵雷达资料能够清晰展现水龙卷超级单体风暴精细化演变特征,0.9 °仰角首先出现风切变,随后风切变出现高度逐渐增高,并加强为中气旋,切变最高高度达到17.1 °仰角,随后高度逐渐降低,龙卷减弱。三维反射率因子图清楚地反映了龙卷母体风暴穹窿结构形成过程,以及强反射率因子区向上延伸,变细加强,龙卷触及水面后变粗的过程。S波段雷达探测到在龙卷发生前,出现ZDR低值眼区和ρHV弧,这对于预报员提前预警以及识别龙卷具有一定帮助。 相似文献
6.
2018年6月8日,在1804号台风“艾云尼”螺旋雨带中发生了两次陆龙卷天气,分别袭击了广州市南沙区横沥镇和佛山市南海区大沥镇。利用广州CINRAD/SA多普勒天气雷达、佛山CINRAD/XD多普勒天气雷达、5 min间隔的地面自动气象站和MICAPS等资料,研究了两次陆龙卷的天气背景、环境参数和龙卷风暴中尺度结构特征。结果表明:广州南沙龙卷为台风环流外围龙卷,位于台风中心的东北象限,强度为EF3级;佛山南海龙卷为台风环流内部龙卷,位于台风中心的东侧,强度为EF1级。龙卷均发生在中低空强东南急流在珠江口附近上下叠加和高层辐散的有利大尺度环流背景下。环境条件表现为较强的低层风垂直切变和较大的风暴相对螺旋度（SRH）、较小的对流有效位能（CAPE）和对流抑制能量（CIN）、极低的抬升凝结高度（LCL）;地面存在中尺度辐合线和小尺度涡旋。广州S波段雷达探测到两次龙卷母风暴的低层钩状回波和入流缺口回波特征及低层中等强度中气旋,龙卷出现在钩状回波顶端、中气旋中心附近。佛山X波段双偏振雷达清晰地探测到佛山南海区大沥龙卷的微型超级单体和龙卷碎片特征（TDS）。 相似文献
7.
2016年6月23日江苏阜宁EF4级龙卷天气分析 总被引：7，自引：0，他引：7
2016年6月23日,江苏省盐城市阜宁县发生了历史罕见的EF4级龙卷,导致99人死亡,846人受伤,并有大量建筑物被损毁。文章利用观测资料对产生强龙卷的天气背景和中尺度特征进行了分析,发现：阜宁龙卷发生在我国东部龙卷最高发的地区和季节,产生龙卷的天气尺度背景为典型的梅雨期暴雨环流,产生龙卷的中尺度对流系统发生在地面暖锋南侧,这里也是高低空急流耦合的区域,与高空急流相伴的动力强迫特征明显,大气热力不稳定条件为中等偏强;产生阜宁龙卷的中尺度对流系统与美国大部分强龙卷相似,为块状的离散单体对流模态,且具有经典超级单体的钩状回波和强中气旋特征,并伴有龙卷涡旋特征（tornado vortex signature,TVS）;龙卷位于钩状回波顶端,主要发生在中气旋底高高度低于1 km期间。 相似文献
8.
利用FY-2E静止气象卫星云图和新一代天气雷达资料,结合常规天气资料对2010年5月15日发生在黑龙江省西部地区的龙卷天气进行分析.通过卫星云图分析环流特征和中尺度特征,讨论了产生龙卷的雷暴云团的形成环境和触发条件,利用天气雷达资料详细阐述了雷暴云团的发生发展过程和产生龙卷天气处的云图及雷达回波特征.结果表明:这次龙卷天气发生在高空槽和地面冷锋前,由多个小尺度对流发展成为α中尺度对流云团所引发的.大的湿度梯度、干侵入、垂直风切变和上干下湿的环境场为龙卷的发生提供了不稳定能量,地面冷锋提供了触发机制,雷暴云团在发展过程中不断生消与合并,在两个云团的交界处产生龙卷.雷达回波上环境大风、入流、下沉气流、中气旋、钩状回波,有界弱回波区等特征回波明显;风暴成熟时,钩状回波、有界弱回波区达到最大,高、中、低三层大风区清晰,下沉气流和入流开始相交并产生出流边界,龙卷就发生在该回波附近. 相似文献
9.
为了探测、分析和研究尺度小、生命史短、致灾重的龙卷等强对流天气三维精细化垂直结构及演变规律,江苏正在龙卷易发区苏北平原建设高时空分辨率的双偏振雷达网。本文为支撑苏北龙卷雷达网建设,从龙卷雷达组网的必要性出发,重点分析苏北龙卷雷达组网策略。研究表明:(1)苏北龙卷雷达网拟采用大天线、全固态、高性能技术指标的X波段双偏振雷达组网,采用不同的观测模式,可获得空间一致性好、时空分辨率高且丰富的探测数据,满足龙卷等强对流天气的快速、精细化探测要求。此外,采用较高的脉冲重复频率等扩展测速范围,解决X波段雷达速度模糊问题。(2)经理论计算与比较,苏北龙卷雷达网可采用正三角形组网拓扑结构,取累计空间密度值90%,雷达间距为60km时,波束直径b_s特征值为282.0m,最低波束高度b_h特征值为52.6m,探测灵敏度Z_(min)特征值为2.7dB;X波段雷达组网与S波段业务雷达相比,在60km探测距离处,其波束直径减小了约2倍,0°仰角盲区高度降低了约1.5倍,探测灵敏度降低了2.4dB。即在方位分辨率、探测盲区、弱回波探测能力、数据空间一致性等方面均得到提升,可提供更多低于1km、甚至百米的高时空分辨率的雷达资料,便于捕捉龙卷等强对流天气。(3)苏北龙卷雷达网在盐都、阜宁、大丰、宝应、兴化(龙卷易发区),各布设一部固定式X波段全固态双偏振多普勒天气雷达。综合考虑在苏北平原雷达选址的各种因素,最终雷达网基本单元拟采用近似正三角形(N=3,L=45～65km)的拓扑结构。5部高时空分辨率的龙卷探测雷达组成3个近似正三角形的单元,镶嵌在S波段雷达业务网内(盐城、淮安、泰州雷达中间)。后续可进一步增加雷达数量及拓宽观测区域,例如在高邮等龙卷易发地区,可增补X波段天气雷达或C波段相控阵天气雷达。 相似文献
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2021年6月1日和6月9日黑龙江省哈尔滨尚志市及阿城区和齐齐哈尔梅里斯区分别发生双龙卷事件。利用常规气象观测、多普勒天气雷达等资料对比分析二者的多尺度特征。结果表明:两次龙卷均发生在东北冷涡的东南象限，高空急流出口区左侧，中低层偏南气流有利于暖湿气流输送和垂直运动发展。6月1日和6月9日分别以短时强降水和雷暴大风天气为主，6月1日水汽条件、垂直运动、0~1 km高度垂直风切变和抬升凝结高度更有利于产生强龙卷，且中尺度气旋维持时间更长。干线与地面辐合线为中尺度触发机制。雷暴冷池出流与中尺度暖锋形成的伪冷锋有利于龙卷的发展和维持。龙卷出现在地面伪冷锋与干线交界处的湿区一侧，冷池前沿，龙卷母云为超级单体。暖湿气流产生的入流缺口是钩状回波发展的前兆，中等到高强度的中尺度气旋在3 km高度产生并发展，5~10 min后触地，当钩状回波与中尺度气旋同时出现时龙卷产生。 相似文献
11.
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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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
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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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Yuepeng PAN Mengna GU Yuexin HE Dianming WU Chunyan LIU Linlin SONG Shili TIAN Xuemei Lü Yang SUN Tao SONG Wendell W. WALTERS Xuejun LIU Nicholas A. MARTIN Qianqian ZHANG Yunting FANG Valerio FERRACCI Yuesi WANG 《大气科学进展》2020,37(9):933-938
正While China’s Air Pollution Prevention and Control Action Plan on particulate matter since 2013 has reduced sulfate significantly, aerosol ammonium nitrate remains high in East China. As the high nitrate abundances are strongly linked with ammonia, reducing ammonia emissions is becoming increasingly important to improve the air quality of China. Although satellite data provide evidence of substantial increases in atmospheric ammonia concentrations over major agricultural regions, long-term surface observation of ammonia concentrations are sparse. In addition, there is still no consensus on 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
20.
《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