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1.
《沙漠与绿洲气象(新疆气象)》2020,(4)
基于常规观测资料、NCEP(1°×1°)再分析资料、FY-2G卫星云图和多普勒雷达资料等对2018年6月10日发生在甘肃省平凉市的冰雹天气过程进行分析,得出以下结论:(1)此次冰雹过程属于典型的西北气流型,高空强冷平流、冰雹发生区明显的切变线和地面辐合线以及高层气流引导地面辐合线附近生成的中尺度对流系统MCS,是造成此次强天气的主要影响系统。(2)中尺度辐合线和干线为此次冰雹天气提供了较好的触发机制;强冰雹发生区螺旋度的异常增大为雹暴系统的发展增强提供了强有力的环境场条件;强垂直风切变可促使不稳定能量释放,形成冰雹等天气,和湿斜压作用共同形成MCS发生发展的有利条件;冰雹发生区0℃层、-20℃层高度及二者之间的厚度均有利于大冰雹的形成。(3)多普勒雷达资料显示,引发强天气的回波单体附近,悬垂回波、弱回波区、钩状回波等特征明显,对应径向速度图有明显的中气旋、中层径向辐合及风暴顶辐散等特征配合,对此次冰雹等天气有很好的指示作用。 相似文献
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河北平原一次春季强对流天气分析 总被引：2，自引：0，他引：2
利用NCEP6小时一次1°×1°再分析资料、常规高空地面资料和自动站、FY-2C卫星云图及石家庄CINRAD/SA型多普勒雷达等资料,从天气形势、物理机制、雷达回波和云图演变特征、地形作用等方面入手,分析了河北平原一次春季强对流天气的演变和成因。结果表明:这次强对流天气过程发生在高空槽由垂直结构向前倾结构转变的过程中,中高层干冷平流、低层暖湿平流的大气层结增强了对流不稳定的发展,飑线是此次强对流天气的直接影响系统;太行山地形和平原南部的中尺度辐合线,对飑线系统的触发、组织、移动具有重要作用,强对流区发生在地面中尺度辐合线南侧的偏南气流里。分析还发现,低层θse高能区、水汽通量大值区、强的辐合上升区和CAPE的高值区等物理量场都与强对流天气区有较好的对应关系。 相似文献
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利用常规气象观测资料、区域加密自动站风场资料、NCEP1°×1°再分析资料和喀什多普勒雷达资料,从天气背景、中尺度特征、物理量和雷达回波特征等方面对2018年春末喀什地区岳普湖县发生的一次致灾冰雹天气成因进行分析。结果表明：本次冰雹天气发生在中亚低涡影响的有利环流背景条件下,中尺度切变线、中尺度地面辐合线及中层干冷空气侵入是产生冰雹的触发系统,冰雹发生前大气处于上干冷、下暖湿的不稳定层结;冰雹云具有反射率强、回波顶高、垂直液态含水量大等特点,冰雹发生时垂直累积液态含水量值发生跃变,对判断冰雹的发生具有明显的指示意义;雷达径向速度场上显示有中小尺度气旋性流场存在,气旋性辐合出现的时间、位置与冰雹出现时间、位置有较好的对应关系,风场气旋性辐合有利于上升运动发展形成小冰雹;垂直风廓线（VWP）产品显示此次冰雹发生在较弱的垂直风切变环境下,弱的垂直风切变不利于上升气流和下沉气流的长时间维持,不利于产生大冰雹。 相似文献
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江苏沿江地区一次强冰雹天气的中尺度特征分析 总被引：11，自引：2，他引：9
利用常规气象资料、卫星、多普勒天气雷达、风廓线雷达等资料,对发生在江苏沿江地区一次强冰雹天气形势背景、环境热动力条件、强冰雹发生前地区环境场变化、超级单体雷达回波中尺度特征等进行了详细分析。结果表明:(1)在东北冷涡槽后干冷气流影响下,中高层干冷、低层暖湿的不稳定层结,高低空急流以及地面辐合系统的配置为此次强对流天气的产生提供了有利热动力条件;高CAPE值、逆温层、低层适当水汽条件及较强的深层垂直风切变有利于强冰雹天气的发生。(2)利用多普勒天气雷达、风廓线仪数据反演垂直分布的物理量场(平均散度、平均垂直速度、相对风暴螺旋度、垂直风切变)能够反映本站上空环境场的快速变化情况:强对流系统移入本站前雷达站上空逐渐调整为低层辐合、中高层辐散的风场配置结构,螺旋度和垂直风切变数值逐渐增加,表明环境场有利于强对流系统的维持发展。(3)强降雹超级单体除具有三体散射现象、入流缺口等雷达回波中尺度特征外,持久深厚的中气旋存在造成了显著的有界弱回波区和高悬垂强回波区。应用双多普勒雷达风场反演技术揭示了超级单体内部环流结构:低层气旋性旋转,中层旋转加强,高层风场辐散。超级单体内部涡旋特征的出现和维持有利于支撑空中大冰雹的增长。 相似文献
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《干旱气象》2017,(5)
利用常规观测资料、中尺度加密气象站资料以及卫星和雷达产品等资料,对2016年7月28日出现在山西中部的一次强对流天气进行综合分析。结果表明:此次强对流天气发生在低涡低槽后部西北气流控制的环流背景条件下;低层切变线、地面辐合线和干线是此次强对流天气的主要触发因素;较低层冷空气的渗透,使得大气层结不稳定度加大,促使垂直上升运动加强,为强对流天气的发展提供了有利条件。强对流发生前,850 h Pa存在明显的逆温层,有利于低层能量积累。对流层高低层湿位涡的正负垂直叠置,使大气对称不稳定性增强,强对流天气发生在湿位涡等值线前沿的湿位涡舌附近、冷暖空气交汇的区域。卫星云图上出现的椭圆形雹暴云团,是造成冰雹大风天气的主要中尺度系统。雷达回波强度图上出现的旁瓣回波和三体散射长钉是典型的冰雹特征,且较降雹时间提前约15~20 min,雷暴大风发生在弓形回波头部、强回波中心断裂处,强回波快速减弱对雷暴大风的发生具有指示意义;径向速度图上出现中等强度的中气旋以及中层明显的径向辐合有利于雷暴大风出现;回波顶高和垂直累积液态水含量(VIL)的跃增表明出现大冰雹的可能,VIL的快速降低也意味着出现雷暴大风的潜势较大。 相似文献
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利用常规探空资料、区域自动站资料、FY2E卫星云图以及青海西宁多普勒雷达资料,对2010年7月6日发生在青海省海晏县境内的一次大范围强对流天气进行了分析。结果表明:哈密附近沿西北气流快速东移南下的短波槽是这次强对流天气的主要影响系统,在北上的东南暖湿气流与西亚槽底分裂冷空气在青海东北部地区交汇、低层辐合高层辐散的强上升运动、午后太阳辐射对地表不均匀加热与上干冷下暖湿的对流不稳定层结的共同作用造成了此次强对流天气,并促使500hPa切变线附近不稳定能量的释放,从而产生中尺度对流复合系统(MCS),在卫星红外和水汽云图上有明显的中β尺度孤立MCS特征,在雷达回波图上表现为有中气旋相伴随的强降水超级单体特征。 相似文献
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利用常规观测资料、加密地面资料、卫星云图和多普勒雷达回波等资料,从天气形势、物理量场和回波演变特征等方面对2011年6月11日午后发生在豫北地区的强对流天气进行分析发现:高空冷平流和24 h显著降温区叠加在低层暖区之上,形成上干冷下暖湿的位势不稳定层结,为强对流的产生提供了层结条件;地面暖低压发展和辐合中心、辐合线是这次强对流天气的触发机制;0-6 km较大的垂直风切变有利于强对流天气的发展和维持。卫星云图和雷达产品显示:对流云团的发展和移动与地面切变线、雷达回波一致,并可预测强天气落区。当回波中心强度≥50 d Bz、回波顶高≥12 km、垂直累积液态含水量≥45 kg/m2时,极易造成短时强降水和冰雹天气。三体散射特征和中气旋的出现对确定发布冰雹预警有指示意义,17:50第一次观测到三体散射特征发布冰雹预警,时效在20~90 min。垂直液态含水量在强降水发生前20 min开始剧增,为判别短时强降水等强对流天气提供有效依据。 相似文献
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利用常规气象观测资料、ECMWF细网格资料、FY-2E卫星云图、喀什新一代多普勒雷达资料和新疆区域自动站气象观测资料,对2013年6月18日发生在新疆喀什地区境内的一次罕见的强冰雹天气从天气形势、中尺度系统、水汽条件、雷达回波特征等方面进行了综合分析。分析显示,此次冰雹天气是在有利的大尺度环流背景下产生的,冰雹出现前,雹区附近低层到地面存在中尺度切变线、涌线和地面中低压等多个中尺度系统;水汽在中低层集中,并不断向冰雹区输送;雹区附近强烈的辐合上升运动为冰雹的出现提供了水汽和动力条件;探空物理量参数有利于大气不稳定能量的聚积和爆发。分析此次强冰雹天气的成因,有利于改进南疆地区冰雹短时和临近预报、预警的基本思路。 相似文献
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利用常规观测资料、卫星云图、雷达、风廓线组网资料对2017年8月8日-9日天津地区局部大暴雨天气进行分析,得到以下结论：A、B两个中尺度雨团先后影响天津,A雨团持续了4个小时,雨强相对较大；B雨团持续了3个小时,雨强相对较小；对应有两个MCS,强降水发生在TBB低值中心偏向温度梯度最大的区域；降水回波的移动路径和强度特征存在差异,A雨团回波为自西北向东南方向移动的带状的高质心降水回波；B雨团回波自西南向东北方向移动,为低质心降水回波带状回波,高质心降水回波雨强高于低质心降水回波。新型探测资料有助于分析中尺度影响系统,判断对流系统的移动方向。用风廓线组网资料对比两个阶段降水的中尺度系统,A雨团为上冷下暖的高低空配置,B雨团降水出现在整层西南气流中,引导风的不同,导致回波的移动方向、天气剧烈程度的不同；变压梯度、温度梯度等环境因素对判断局地对流暴雨发生的环境条件有一定指示性。 相似文献
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This paper reviews the main theoretical progress of mesoscale weather dynamics since 2003, including： （1） The dynamic mechanisms of balanced and unbalanced flow are applied to study the genesis and development problems of mesoscale circulation. The symmetric instability and transverse-wave instability are analyzed in line and vortex atmosphere convection, and further research has been done on nonlinear convective symmetric instability. The interaction between forced convection and unstable convection and the wave characteristics of mesoscale motion are also discussed. （2） Intermediate atmosphere dynamic boundary layer models are developed. The complicated nonlinear interaction is analyzed theoretically between the atmospheric boundary layer and the free atmosphere. The structure of the topography boundary layer, atmospheric frontogenesis, the structure and circulation of the low-level front and other boundary layer dynamic problems are discussed. （3） The formation and development of meso-β-scale rainstorms under the background of the East-Asia atmosphere circulation are diagnosed with the variation of MPV （moist potential vorticity） anomalies. And some physical vectors are modified and applied in the moist atmosphere. 相似文献
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一次中纬度特大暴雨过程的中尺度分析 总被引：4，自引：0，他引：4
用Shuman-Shapiro中尺度滤波方法，结合大尺度环流背景，对1999年8月11－12日山东半岛特大暴雨过程进行了中尺度分析。结果表明，这将过程是热带中尺度气旋北上发展造成的；地面冷空气侵入西移的中尺度低压所导致的对流发展，是热带中尺度气旋发展的原因；大尺度环境场丰富的水汽输送为强对流的发展和维持提供了能源保障；地面中尺度低压中心和与其配置的切变线上的波动点对降水落区有指示意义。 相似文献
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贵州南部一次突发性大暴雨的中尺度分析 总被引：9，自引：0，他引：9
利用地面加密观测资料、贵州自动站雨量资料、FY-2C卫星红外辐射亮度温度(tbb)资料等,对2006年6月12日夜间贵州南部突发性大暴雨过程进行了中尺度分析.结果表明:具有类似于MCC(Mesoscale Convective Complex)特征的中尺度对流云团的发生发展及其缓慢东移是造成此次大暴雨的直接原因.对流层中低层大量的水汽输送和对流有效位能的积累为大暴雨的形成提供了有利的环境条件,中高层弱冷空气入侵使偏南暖湿气流被迫抬升、地面中尺度低压和辐合线的形成是暴雨发生的可能触发机制.中尺度天气系统具有低层辐合、高层辐散的高、低空配置,暴雨区南、北两侧的正、反垂直环流构成了中尺度次级环流圈的垂直结构特征. 相似文献
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典型超级单体风暴过程分析 总被引：10，自引：2，他引：8
利用郑州７１４ＣＤ多普勒天气雷达观测资料,结合有关地面要素资料和郑州探空资料,对１９９８年９月４日一次典型超级单体造成的冰雹大风和短时强降水过程进行分析探讨,揭示了强对流天气雷达回波强度场和多普勒速度场的典型特征,为强对流天气的监测、识别、临近预报和人工消雹提供参考。 相似文献
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The Evolution of a Meso-β-Scale Convective Vortex in the Dabie Mountain Area 总被引：1，自引：0，他引：1 
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下载免费PDF全文 The evolution of a mesoscale convective system (MCS) that caused strong precipitation in the northern area of Dabie Mountain during 21-22 June 2008 is analyzed, along with the evolution of the associated meso-β-scale convective vortex (MCV). The mesoscale reanalysis data generated by the Local Analysis and Prediction System (LAPS) at a 3-km horizontal resolution and a 1-h time resolution during the South China Heavy Rainfall Experiment (SCHeREX) were utilized. The results show that two processes played key roles in the enhancement of convective instability. First, the mesoscale low-level jet strengthened and shifted eastward, leading to the convergence of warm-wet airflow and increasing convective instability at middle and low levels. Second, the warm-wet airflow interacted with the cold airflow from the north, causing increased vertical vorticity in the vicinity of steeply sloping moist isentropic surfaces. The combined action of these two processes caused the MCS to shift progressively eastward. Condensation associated with the MCS released latent heat and formed a layer of large diabatic heating in the middle troposphere, increasing the potential vorticity below this layer. This increase in potential vorticity created favorable conditions for the development of a low-level vortex circulation. The vertical motion associated with this low-level vortex further promoted the development of convection, creating a positive feedback between the deep convection and the low-level vortex circulation. This feedback mechanism not only promoted the maturation of the MCS, but also played the primary role in the evolution of the MCV. The MCV formed and developed due to the enhancement of the positive feedback that accompanied the coming together of the center of the vortex and the center of the convection. The positive feedback peaked and the MCV matured when these two centers converged. The positive feedback weakened and the MCV began to decay as the two centers separated and diverged. 相似文献
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常规资料获取中尺度信息的一种简便方案 总被引：9，自引：1，他引：9
基于Ｂａｒｎｅｓ滤波原理，利用低通滤场的连续性特征，设计了一种从观测资料中提取中尺度气象信息的简便方案。利用该方案，可独立地获得观测站网和规则网格点上的中尺度气象信息，为基层气象台站进行中分析提供了方便。该方案与过去方案相比，具有计算量小，速度快，程序设计简单，计算精度高等优点，尤其适合基层台站使用。 相似文献
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Mesoscale research conducted by Chinese meteorologists during the past four years is reviewed.Advances in theoretical studies include (a) mesoscale quasi-balanced and semi-balanced dynamics, derived through scale analysis and the perturbation method which are suitable for describing mesoscale vortices;(b) subcritical instability and vortex-sheet instability; (c) frontal adjustment mechanism and the effect of topography on frontgenesis; and (d) slantwise vorticity development theories, the slantwise vortex equation,and moist potential vorticity (MPV) anomalies with precipitation-related heat and mass sinks and MPV impermeability theorem. From the MPV conservation viewpoint, the transformation mechanism between different scale weather systems is analyzed. Based on the data analysis, a new dew-point front near the periphery of the West Pacific subtropical high is identified. In the light of MPV theory and Q-vector theory, some events associated with torrential rain systems and severe storms are analyzed and diagnosed.Progress in mesoscale numerical simulation has been made in the development of meso-α, meso-β vortices,meso-γ-scale downbursts and precipitation produced by deep convective systems with MM5 and other mesoscale models. 相似文献
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Vorticity budget investigation of a simulated long-lived mesoscale vortex in South China 总被引：2，自引：0，他引：2
A vorticity budget investigation is performed using the output data from a numerical simulation of a typical MCV (mesoscale convectively generated votex) case in South China. Results suggest that the divergence caused by convection in the low troposphere is the main producer of positive vorticity, while vertical vorticity transferred by the tilting term from the horizontal vorticity compensates the upward output of cyclonic vorticity. Scale analyses of the vorticity equation suggest that the advection of planetary vorticity can be neglected owing to the low latitude, which is different from the larger scale systems in high latitude areas. In addition, the distribution of relative vorticity tendency on pressure level is not uniform. A vortex will move along the vector from the negative to the positive vorticity tendency region. The mechanism of the phenomenon-that nearly all of the convectively ascending region is located southward/southeastward of the vortex center-is also discussed. Convergence with regard to latent heat release would be in favor of the spin-up of meso-vortex, however, the horizontal vorticity caused by windshear is tilted by vertical motion due to convection. Consequently, the negative and positive vorticity tendencies are located symmetrically about the convective center, which suggests that the vortex southward movement is dynamically driven by convection. 相似文献
20.
In this study, the accuracy of a Pennsylvania State University-National Center for Atmospheric Research mesoscale model (PSU/NCAR MM5) for predicting heavy summer precipitation over the Korean Peninsula was investigated. A total of 1800 simulations were performed using this model for 30 heavy rainfall events employing four cumulus parameterization schemes (CPS), two grid-scale resolvable precipitation schemes (GRS), and two planetary boundary layer (PBL) schemes in three model resolutions (90 km, 30 km, and 10 km). The heavy rainfall events were mesoscale convective systems developed under the influence of mid-latitude baroclinic systems with low-level moisture transport from the ocean. The predictive accuracy for maximum rainfall was approximately 80% for 10-km resolution and was 60% for 30-km resolution. The predictive accuracy for rainfall position extended to ～150 km from the observed position for both resolutions. Simulated rainfall was most sensitive to CPS, then to PBL schemes, and then to GRS. In general, the Grell (GR) scheme and the Anthes and Kuo (AK) scheme showed a better prediction capability for heavy rainfall than did the Betts-Miller (BM) scheme and the Kain-Fritsch (KF) scheme. The GR scheme also performed well in the 24-h and 12-h precipitation predictions: the parameterized convective rainfall in GR is directly related to synoptic-scale forcing. The models without CPS performed better for rainfall amounts but worse for rainfall position than those with CPS. The MM5 model demonstrated substantial predictive capacity using synoptic-scale initial conditions and lateral boundary data because heavy summer rainfall in Korea occurs in a strong synoptic-scale environment. 相似文献