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1.
一次东北冷涡不同阶段强对流天气特征对比分析 总被引：3，自引：0，他引：3
利用NCAR/NCEP再分析（1?×1?）资料、区域自动站观测、FY-2D/2E卫星观测和GPS/MET水汽监测等资料,对2012年6月7-18日长春地区发生在同一东北冷涡系统不同演变阶段的3次强对流天气进行对比诊断分析。结果表明：在冷涡形成期,高低空急流耦合产生的次级环流上升支,触发锋前不稳定能量释放,导致中β尺度孤立深厚湿对流系统出现;在冷涡发展期,对流层高层干冷空气向对流层中下层侵入,形成高空露点锋,触发有组织的中α尺度对流系统;在冷涡消亡期,低涡减弱为高空槽并快速东移,其后部冷空气置于低层大范围暖湿空气之上,地面中尺度辐合触发不稳定能量释放,形成中β尺度对流系统。 相似文献
2.
多普勒雷达资料在冷涡强对流天气中的同化应用试验 总被引：3，自引：0，他引：3
应用WRF模式的三维变分同化系统(WRF-3DVAR),对沈阳多普勒天气雷达资料在东北冷涡暴雨个例中的同化应用进行了试验.研制了多普勒雷达资料质量控制系统,实现了对径向风和反射率因子的直接同化,不但可以反演中尺度三维气象要素场,而且可以为模式提供初始场.以天气尺度资料为背景场同化多普勒雷达资料,WRF-3DVAR可以较好地反演冷涡中尺度对流系统的三维结构,反演的地面强对流辐散气流及在对流层中层涡旋都符合中尺度系统概念模型,通过与实际地面探测资料进行了对比,风场环流基本接近,同化了雷达资料的气象要素场可为预报业务提供较好的包含中小尺度系统的实时三维分析场.通过冷涡个例同化试验,应用WRF-3DVAR同化雷达资料后,中尺度模式对对流降水的预报总体有正的影响,对强对流中的一些中小尺度雨团的预报也略有改善. 相似文献
3.
陕西一次持续性强对流天气过程的成因分析 总被引：7，自引：2，他引：5
利用常规资料、地面加密资料、TBB和NCEP再分析等资料,对2006年6月23—25日陕西一次持续性的强对流天气过程进行了天气动力学诊断和中尺度特征分析。结果表明：（1）这次持续性的强对流天气发生在蒙古冷涡的大尺度环流背景下,从冷涡底部分裂的下滑冷槽是强对流天气的影响系统;中高层冷槽和低层暖温度脊、湿舌的上下叠置,有利于对流不稳定的建立和发展。（2）对流层低层850 hPa附近的逆温层所形成的干暖盖,更有利于深厚对流活动的发生;大气温度直减率越大越有利于雷暴大风的发生,对流有效位能（CAPE）和垂直风切变的大小与对流性天气的强弱有很好的对应关系。（3）23和24日的强对流天气是由生命史达6小时左右的β中尺度雹暴云团造成,而25日的剧烈天气是由生命史达10小时左右的α中尺度飑线云团造成。（4）地面辐合线或干线是触发强对流天气的因子之一,对流单体一般生成于地面辐合线附近,在地面辐合线与干线结合处易于对流单体或云团的新生和发展。 相似文献
4.
利用常规气象观测资料、自动站资料、卫星、雷达和NCEP再分析资料,针对2015年8月22日冷涡背景下华北东北部和黄淮地区同时出现的不同类型强对流天气,对比分析引发不同天气的两种中尺度对流系统的演变过程及冷涡背景下不同强对流天气的成因。具体结论如下:(1)同一冷涡背景下,华北东北部位于冷涡中心外围西南象限和地面冷高压前沿,触发的分散性多单体风暴位于冷涡外围的涡旋云系中,引发以短时强降水为主的强对流天气;黄淮地区位于冷涡后部和地面冷锋前,槽后晴空区的多个对流单体,合并后形成人字形飑线系统引发短时强降水、冰雹和雷暴大风天气;(2)环境热力和水汽的差异为形成不同的强对流天气提供了前提条件:华北东北部受高层暖脊影响,地面高压后部的偏东气流带来水汽输送,整层暖湿的条件利于产生强降水;黄淮地区高层有补充干冷空气,利于热力不稳定条件发展,但黄淮地区低层水汽不足,风雹天气在较干环境场中不易被触发;(3)引发不同强对流天气的对流触发机制不同,两处的初始对流均受同一地面辐合线影响,但华北东北部在地形抬升与辐合线共同作用下不断新生单体;黄淮地区的初始局地热对流形成后,其前沿的辐散出流与环境风形成新的辐合,使原辐合线断裂和转向;(4)出现不同强对流天气时垂直风切变不同,黄淮风雹区的中层垂直风切变更显著,有利于形成持续性的强风暴;强对流天气发生时,华北东北部中低层风场的演变与天气尺度系统的变化有关,黄淮地区中低层风的垂直分布与中尺度对流系统的发生发展有关。 相似文献
5.
不同类型大尺度环流背景下强对流天气的短时临近预报预警研究 总被引：19，自引：6，他引：13
利用常规气象资料、自动站资料、卫星资料、NCEP再分析资料,对2001—2010年安徽省强对流天气过程的物理机制、中尺度特征进行分析。结果表明：强对流天气其发生发展和一定的大尺度环流背景场有关,强对流发生的天气学条件即：丰富水汽、不稳定层结、抬升触发机制或强上升运动,强烈发展的强风暴常有逆温层、强的风垂直切变、中层干冷空气等有利条件。然而,这些条件在不同的大尺度环流背景下各要素的重要性不尽相同,产生的强对流天气类型也不相同。冷涡槽后类对流不稳定表现在中低层温度直减率大;风垂直切变强,风随高度强烈顺转,400～500 hPa有西风急流存在,且与强对流天气的发生区域紧密相关;存在明显的中尺度低压和辐合线、干线;主要造成雷雨大风和冰雹天气。槽前类通常对流不稳定能量较大,中低层有急流存在,风速水平切变和垂直切变大;快速东移的短波槽是触发强对流天气的主要机制;低层水汽条件较好;主要导致雷雨大风、短时强降水和龙卷天气。通过对不同类型大尺度环流背景下强对流天气各天气要素和物理量统计,提取环境场消空指标,明显提高了基于多普勒雷达反射率因子和平均径向速度的龙卷识别和预警水平。对比分析了2010年7月19—20日发生在副高边缘槽前类和在东北冷涡形势下的2009年6月3日、5日、14日在黄淮和江淮地区分别产生飑线并造成大范围雷雨大风、冰雹等强对流天气产生的物理机制、中尺度特征差异,提高对不同类型大尺度环流背景下强对流天气的短时、临近预报水平。 相似文献
6.
一次东北冷涡过程的数值模拟与降水分析 总被引：2，自引：2，他引：0
本文利用WRF模式对2007年7月8日至12日的东北冷涡过程进行模拟。通过分析天气尺度背景场可知, 在对流层中高层出现干侵入过程, 干空气主要来源于我国内蒙古西部和东北冷涡的西北部, 随着东北冷涡一起呈涡旋状运动, 在对流层中层的干侵入更加明显; 东北冷涡的东部为水汽通量辐合区, 说明此处水汽丰沛, 该处的暖湿空气与干冷空气相汇, 有利于降水的生成。通过分析中尺度对流系统的地面和对流层中下层的风场结构可知, 中尺度对流系统易发生在东北冷涡东南侧和东北侧的气旋性曲率最大处, 此处的对流层低层易形成强辐合区, 而风场的水平辐合运动激发出垂直上升运动, 在对流不稳定区配合着强上升运动, 有利于对流系统发展而产生降水, 因此在低压系统东南侧及东北侧的 “气旋曲度” 区易形成降水。从对流涡度矢量的垂直分量可知, 在东北冷涡中的东南侧和东北侧, 对流涡度矢量的垂直分量对于中尺度系统的发生位置和降水区域有很好的指示作用。 相似文献
7.
《干旱气象》2016,(3)
利用常规气象资料、区域加密观测站资料、雷达资料以及WRF模式输出资料,对一次漏报的受弱冷空气影响而引发的鲁中山区局地强对流天气过程进行诊断。结果表明,此次过程发生在500h Pa浅槽引导弱冷空气自对流层中层缓慢下沉造成气层位势不稳定的天气背景下,强对流在触发和加强的过程中复杂下垫面的影响有不可忽视的作用。局地对流易在山区西北边界的迎风坡、地面中尺度低压中心、温度梯度最大处触发;山区地形对垂直环流的激发是对流发展的主要原因;地形造成的近地面来自海上的东南风绕流辐合是对流加强的有利因素;在环境场较弱的情况下,局地对流触发后,强雷暴回波会沿着地面中尺度高能区发展、移动。 相似文献
8.
一次华北飑线天气过程中环境条件与对流发展机制研究 总被引：12，自引：6，他引：6
利用多种观测和分析数据对2008年6月23日午后华北地区一次持续时间较长的强飑线天气过程进行了研究。分析表明这是一次在夏季冷涡背景下发生的强对流天气过程,相对孤立的MCSs在副冷锋附近发生发展。此次飑线天气过程中强风暴对流单体、超级单体活跃,对流组织化过程与地面风场辐合线以及锋面有紧密的关系。天气分析表明22日夜间主冷锋过境后,变性高压后部的偏东风以及偏南回流导致在华北东部的锋区开始增强,通过地面观测订正的探空分析表明,对流天气发生前华北地区局地具有较明显的对流潜势。从23日午后开始,河套地区对流层中低层有明显的短波槽扰动发展,在冷涡后部有副冷锋向华北地区逼近,对流的触发与副冷锋密切相关,并通过次级环流方程进一步诊断了锋面所造成的垂直运动;来自气旋后部对流层中高层的强下沉气流,造成了华北地区垂直方向上干湿对比明显,形成较强位势不稳定,有利于对流的触发以及地面大风的形成。通过对垂直风廓线结构和飑线移动速度的分析,表明在此次过程中冷池边界扩张速度与低层风垂直切变大致相当,因此MCS具有较强的强度并维持较长时间。 相似文献
9.
《高原气象》2015,(6)
以2009年6月8日个例为主,对东北冷涡造成的华北暴雨的卫星云图、雷达回波特征及降水特点进行了分析,并利用NCEP FNLs分析资料分析了东北冷涡的非对称结构特征、对流不稳定的建立过程和可能的释放机制。结果表明:东北冷涡具有非对称结构特征;除对流层中层风场、温度场结构较对称外,冷涡在对流层高层对应低槽、暖中心和高空急流,在对流层低层对应倒槽、暖舌,冷中心不明显;冷涡的负涡度、主要辐合辐散和上升运动中心分布在冷涡东南部;在冷涡东南部,对流层中层自西北伸向东南的干冷平流叠加在自西南伸向东北的暖湿平流上,造成对流不稳定迅速增长,且午后晴空辐射增温进一步加强了对流不稳定;冷涡系统建立对流不稳定的同时,冷涡东南部的上升运动为对流有效位能的释放提供了有利条件。 相似文献
10.
一次冷涡发展阶段大暴雨过程的中尺度对流系统研究 总被引：7，自引：0，他引：7
利用2009年东北暴雨试验资料、常规气象观测资料、自动站资料、FY-2C卫星资料和NCEP再分析资料,对2009年6月19日东北地区一次短时强降水过程的天气尺度环流特征、中尺度对流系统(MCS)环境场及其触发机制进行了分析,概括了此次冷涡发展阶段暴雨过程的三维概念模型.结果表明,此次强降水系统主要发生在东北冷涡的发展阶段,造成强对流天气的系统尺度较小、突发性强,具有明显的β-γ中尺度对流系统的特点.高温高湿及位势不稳定层结、低层的湿舌北伸及中层干冷空气的侵入,为MCS的发生、发展提供了非常有利的环境条件.位于高空西风急流出口区北侧和偏东北大风中心入口区南侧的暴雨区上层有强的高空辐散,与辐合区南侧的低空急流前部相互耦合,使得暴雨区上升气流增强;高空急流出口区南侧的偏南风低空急流加强了风暴的人流强度,为风暴提供了有利的风场环境和水汽条件.暴雨区西南侧中低层存在干空气侵入,使中低层干冷空气迅速向对流风暴发生区输送,形成逆温层.在强对流爆发前,中低层的逆温层与上层的干层分开,使风暴发展所需的不稳定能量得以累积,冷涡系统东移引导低层偏西北气流南下,增强了地面流场的辐合,是触发初始对流的关键因素. 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
12.
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
14.
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
15.
《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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17.
<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
18.
《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
19.
《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
20.
《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