共查询到20条相似文献，搜索用时 275 毫秒
1.
山东半岛致灾大暴雨成因个例分析 总被引：4，自引：0，他引：4
对2006年7月27日山东半岛东部致灾暴雨的成因进行了分析,暴雨是由4个中β尺度的对流云团影响产生的.在华南沿海登陆的0605号热带低压"格美"的倒槽、高空西风槽和副热带高压相互作用,在热带低压的东部和副热带高压的西侧形成偏南风低空急流,建立起通向暴雨区的水汽通道.低层暖湿气流的输送,使得中低层大气高温高湿和对流性不稳定.在低空南风急流的左前方,辐合、正涡度和上升运动发展,正k螺旋度增强;高空槽前西南风急流的右后侧,辐散和负涡度发展,负k螺旋度猛烈发展,对低层产生抽吸作用,加强了低层的辐合上升运动,触发对流不稳定能量释放,中尺度对流云团发展,造成强降水. 相似文献
2.
对2020年7月22日山东半岛一次极端暴雨天气过程开展观测分析,并利用中尺度模式WRF对此次局地降水过程进行了高分辨率数值模拟,对暴雨过程进行了天气背景和中尺度降雨的诊断。WRF模式较好地再现了此次极端暴雨过程,结果表明：此次极端暴雨过程短时降水强度大且局地性强,在时空上具有明显中尺度特征。降水发生在北抬副热带高压与华北低涡底部之间的西南气流中,强低涡与低空急流是影响此次降水的重要天气系统。西南急流为本次暴雨过程极端水汽的主要输送载体;在弱高空辐散场下,从地表延伸至500 hPa高空的深厚低涡是造成本次暴雨的主要影响因子,其时空演变特征与中尺度云团变化一致,与暴雨的发生直接相关。低涡、低空急流和副高之间的相互作用使低涡加强发展,低涡南部有暖湿气流入流,北部有干冷气流流入,比湿梯度基本呈现为自南向北递减分布,是典型的伴有低空急流的中尺度低涡流场分布;低涡辐合及其与副热带高压边缘强风速带的共同作用,导致强垂直运动发展并维持,是造成本次山东半岛极端暴雨的重要原因。 相似文献
3.
利用地面观测资料、FY-2C卫星红外云图及中尺度数值模式WRF对2010年7月19-20日河北省南部和中东部一次区域性大暴雨过程进行了诊断分析和数值模拟研究。结果表明,海上热带低压对西南涡的稳定和维持有远距离作用。由于热带低压的存在而促使西南低涡的发展,使西南低空急流在河北突然增强,降水得以再度加强;冷空气从高空侵入、下沉,加强了大气斜压性,迫使对流层中层空气的抬升,为西南涡的发展提供了动力条件;暖湿气流主要来自西南涡携带的西南气流及海上低压和西太平洋副热带高压的东南气流输送,为暴雨加强提供了充沛的水汽和热力条件。 相似文献
4.
海南2008年秋季持续性暴雨过程的物理机制分析 总被引：2，自引：0，他引：2
利用地面常规与加密自动站降水观测、卫星云图、NCEP FNL全球分析等资料对2008年10月12—14日海南持续暴雨天气过程进行诊断分析。分析表明:热带低压、冷空气以及副热带高压三者的相互作用,导致海南低空出现持续的东(东南)风急流,该急流在海南东部沿海形成的向岸风辐合及地形强迫抬升是MCS的重要触发机制,其暖湿输送作用是暴雨区不稳定能量得以循环建立的主要途径。南海东北风冷涌前沿强辐合、潜热加热以及高空强辐散有利于热带扰动的发展与维持。热带低压与冷空气相互作用导致大气斜压性增强,地转强迫作用与惯性振荡机制使得低压北侧东北风急流加强。东北与东南急流之间的形变与辐合导致持续锋生过程,锋生强迫产生的热力直接环流上升支与低空急流左前侧次级环流上升支是对流系统发展的主要动力触发机制,低空强潜热加热也有利于对流向更高层次发展。 相似文献
5.
低涡与急流对"04.9"川东暴雨影响的分析与数值模拟 总被引：23，自引：11，他引：12
2004年9月3日～5日川东出现了大范围的强暴雨过程,本文分析了这次暴雨过程的云图特征和环流形势,并利用MM5中尺度数值模式对本次暴雨进行了二重嵌套模拟,分析及模拟结果表明,本次降水过程与中尺度云团、高低空急流和对流层中低层涡旋活动密切相关,同时还与副热带高压活动和“桑达”台风活动相关。盆地涡出现在低空急流的左侧,而川东强降水发生在高空急流的南面、低涡东南侧与西南低空急流大风出口区之问。盆地正涡度维持有利于盆地上空垂直上升运动的发展和维持,对暴雨的发生提供了动力条件。垂直上升运动是高低空急流和盆地涡联系的纽带,也是盆地涡动力驱动的结果。分析结果还表明,西南低空急流在暴雨出现前建立,暴雨和盆地涡同时出现,而暴雨、低空急流和盆地涡几乎同时减弱。高空急流在过程前和过程中是逐步加大,当高空急流出现剧减时,预示暴雨即将结束。 相似文献
6.
7.
江苏一次持续性梅雨锋暴雨过程诊断与分析 总被引：3，自引：3，他引：0
利用NCEP再分析资料,FY2E卫星的TBB资料,常规和加密气象站资料,对2012年7月2—4日,江苏省一次持续性梅雨锋暴雨过程进行了诊断和中尺度特征分析。结果表明:此次过程是东北冷涡槽东移与副热带高压西北侧暖湿气流交汇形成的。暴雨落区在低空西南急流的左侧和中高空急流的一、三象限,低层干线触发了不稳定能量的释放。经分析有7个中尺度云团造成了本次持续性暴雨,-64℃的冷云盖是较强降水的指标性温度,不断东移的中尺度云团类似于"列车效应",带来持续降水,降水开始时间落后于中尺度云团生成时间约2~4 h。地面中尺度辐合线是触发此次强降水的重要中尺度系统,辐合线附近易触发对流,且对流降水沿着辐合线方向移动。低层正、高层负的垂直螺旋度,高温高湿的大气以及较高的位势不稳定为暴雨和强对流天气提供有利条件。在垂直上升运动区北侧有明显下沉运动补偿气流,使上升气流得以长时间维持。暴雨区位于925 hPa超低空急流核移动方向的左侧。 相似文献
8.
引发梅雨锋暴雨的频发型中尺度低压(扰动)的诊断研究 总被引：17，自引：6，他引：11
利用再分析资料及加密观测资料,对1999年6月下旬有利大尺度环境条件下长江中下游地区梅雨锋上频发的5个中尺度低压(扰动)进行了诊断研究.由合成分析得到了长江中下游地区中尺度低压(扰动)的基本特征(共性);依其特征将之归纳为两种类型;之后选择两个典型个例分析了它们各自发生发展过程中特征的异同(个性).分析结果揭示了梅雨锋中尺度低压(扰动)的动力和热力结构特征、暴雨过程中对流活动的详细过程及典型雨团的路径和生命史.此外,高山站每小时的风记录等信息反映出低空西南急流和其上大风速中心同中尺度低压(扰动)及暴雨发生演变过程有密切关系.高空急流对中尺度低压(扰动)的发展及暴雨有明显的作用,有无高空西风急流与低空急流的耦合似乎是未来发展与不发展中尺度低压(扰动)之间重要的动力学区别之一. 相似文献
9.
利用非常规观测资料对上海特大暴雨过程的模拟研究 总被引：12，自引：4，他引：8
2001年8月5～6日,上海市区出现了建国以来破记录的一次特大暴雨.天气形势分析表明,停滞在上海的热带低压和主体位于海上的西太平洋副热带高压为此次特大暴雨的发生提供了有利的环流背景,而低压内部特有的动力、热力结构及在其内发生发展的一系列中尺度对流云团与此次暴雨的发生有直接的关系.作者利用非静力中尺度数值模式MM5V3对此次暴雨过程进行了数值模拟研究,结果表明:在非静力中尺度模式全物理过程的模拟中,采用牛顿张弛逼近法的四维资料同化方案来同化分析场和云顶亮温及上海地面气象自动站等非常规观测资料,模拟结果不仅基本上再现出大尺度及天气尺度系统的发展演变过程,而且还较好地模拟出了此次城市强暴雨过程的雨量空间分布及时序变化.因此,将较高时空密度的非常规观测资料用于高分辨率MM5中尺度数值模式,对于有效地预报城市灾害性暴雨是必要和有意义的.研究还揭示:与热带低压相伴随的偏南暖湿气流不仅是此次暴雨过程的强水汽及热量输送带,而且也是热带低压和其内中尺度对流系统维持发展的必要条件;造成暴雨的中尺度对流系统垂直向上是一具有相对暖心、高湿且低空湿对流不稳定结构的气旋性涡旋,其内强上升运动与涡柱内低空辐合、高空强辐散密切联系. 相似文献
10.
利用MICAPS常规资料和NCEP再分析资料,对2013年7月辽宁省降水异常物理机制进行了研究。结果表明:2013年7月辽宁省降水偏多发生在异常环流背景下,乌拉尔山高压脊和贝加尔湖低压槽强度大于常年,冷空气偏强且路径偏南;东亚40°—50°N处在纬向强锋区中,有利于气旋生成发展;副热带高压脊线比常年偏北2个纬度,西北侧暖湿气流活跃。7月中高纬地区有3次明显冷空气向南侵入至40°N,与中低纬北上至40°N及以北的暖湿气流交绥形成暴雨,影响系统分别为华北气旋、蒙古气旋冷锋和副热带高压西侧辐合线,不同影响系统暴雨过程的物理机制存在差异。3次暴雨过程中,华北气旋暴雨水汽供应最充沛,水汽源地不仅有西太平洋、南海、东海和黄海,还有孟加拉湾;暴雨区水汽主要由副热带高压外围西南或偏南气流向北输送,东海北部和黄海是水汽汇合及输送量最大的区域。高空急流受贝加尔湖低槽强度影响,不同影响系统高空急流演变和强度不同,低空急流分布与强度及高空辐散区、低空辐合区相对高、低空急流轴分布的位置也不同;高、低空急流耦合发展及高空辐散区、低空辐合区叠置产生的强垂直上升运动造成了水汽强烈辐合,其中华北气旋暴雨水汽辐合最强,水汽辐合层顶达850hPa,蒙古气旋冷锋和副热带高压西侧辐合线暴雨水汽辐合顶在900hPa附近及以下。热力分析表明,3次暴雨过程环境大气中层均有干冷空气侵入,增加了降水对流的不稳定性。 相似文献
11.
Using the International Comprehensive Ocean-Atmosphere Data Set(ICOADS) and ERA-Interim data, spatial distributions of air-sea temperature difference(ASTD) in the South China Sea(SCS) for the past 35 years are compared,and variations of spatial and temporal distributions of ASTD in this region are addressed using empirical orthogonal function decomposition and wavelet analysis methods. The results indicate that both ICOADS and ERA-Interim data can reflect actual distribution characteristics of ASTD in the SCS, but values of ASTD from the ERA-Interim data are smaller than those of the ICOADS data in the same region. In addition, the ASTD characteristics from the ERA-Interim data are not obvious inshore. A seesaw-type, north-south distribution of ASTD is dominant in the SCS; i.e., a positive peak in the south is associated with a negative peak in the north in November, and a negative peak in the south is accompanied by a positive peak in the north during April and May. Interannual ASTD variations in summer or autumn are decreasing. There is a seesaw-type distribution of ASTD between Beibu Bay and most of the SCS in summer, and the center of large values is in the Nansha Islands area in autumn. The ASTD in the SCS has a strong quasi-3a oscillation period in all seasons, and a quasi-11 a period in winter and spring. The ASTD is positively correlated with the Nio3.4 index in summer and autumn but negatively correlated in spring and winter. 相似文献
12.
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
13.
Various features of the atmospheric environment affect the number of migratory insects, besides their initial population. However, little is known about the impact of atmospheric low-frequency oscillation(10 to 90 days) on insect migration. A case study was conducted to ascertain the influence of low-frequency atmospheric oscillation on the immigration of brown planthopper, Nilaparvata lugens(Stl), in Hunan and Jiangxi provinces. The results showed the following:(1) The number of immigrating N. lugens from April to June of 2007 through 2016 mainly exhibited a periodic oscillation of 10 to 20 days.(2) The 10-20 d low-frequency number of immigrating N. lugens was significantly correlated with a low-frequency wind field and a geopotential height field at 850 h Pa.(3) During the peak phase of immigration, southwest or south winds served as a driving force and carried N. lugens populations northward, and when in the back of the trough and the front of the ridge, the downward airflow created a favorable condition for N. lugens to land in the study area. In conclusion, the northward migration of N. lugens was influenced by a low-frequency atmospheric circulation based on the analysis of dynamics. This study was the first research connecting atmospheric low-frequency oscillation to insect migration. 相似文献
14.
The atmospheric and oceanic conditions before the onset of EP El Ni?o and CP El Ni?o in nearly 30 years are compared and analyzed by using 850 hPa wind, 20℃ isotherm depth, sea surface temperature and the Wheeler and Hendon index. The results are as follows: In the western equatorial Pacific, the occurrence of the anomalously strong westerly winds of the EP El Ni?o is earlier than that of the CP El Ni?o. Its intensity is far stronger than that of the CP El Ni?o. Two months before the El Ni?o, the anomaly westerly winds of the EP El Ni?o have extended to the eastern Pacific region, while the westerly wind anomaly of the CP El Ni?o can only extend to the west of the dateline three months before the El Ni?o and later stay there. Unlike the EP El Ni?o, the CP El Ni?o is always associated with easterly wind anomaly in the eastern equatorial Pacific before its onset. The thermocline depth anomaly of the EP El Ni?o can significantly move eastward and deepen. In addition, we also find that the evolution of thermocline is ahead of the development of the sea surface temperature for the EP El Ni?o. The strong MJO activity of the EP El Ni?o in the western and central Pacific is earlier than that of the CP El Ni?o. Measured by the standard deviation of the zonal wind square, the intensity of MJO activity of the EP El Ni?o is significantly greater than that of the CP El Ni?o before the onset of El Ni?o. 相似文献
15.
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
16.
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
17.
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
18.
Fei LIU Chen XING Jinbao LI Bin WANG Jing CHAI Chaochao GAO Gang HUANG Jian LIU Deliang CHEN 《大气科学进展》2020,37(7):663-670
正The Taal Volcano in Luzon is one of the most active and dangerous volcanoes of the Philippines. A recent eruption occurred on 12 January 2020(Fig. 1a), and this volcano is still active with the occurrence of volcanic earthquakes. The eruption has become a deep concern worldwide, not only for its damage on local society, but also for potential hazardous consequences on the Earth's climate and environment. 相似文献
19.
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
20.