Synoptic and dynamic analysis of a flash flood-inducing heavy rainfall event in arid and semi-arid central-northern Iran and its simulation using the WRF model     

《Dynamics of Atmospheres and Oceans》2021

The synoptic and dynamic aspects of heavy rainfall occurred on 5th May 2017 and caused flash flooding in arid and semi-arid central-northern Iran is analyzed by the Weather Research and Forecasting (WRF) model. This system synoptically is attributed to a surface low-pressure centered over southern Iran extended to the central parts, linking to a mid-tropospheric tilted-trough over western Iran, and advecting significant moisture from the Mediterranean Sea and the Red Sea to the studied area. The dynamical analysis revealed that the penetration of the upper-tropospheric potential vorticity streamer up to 300 hPa level was not related to such heavy rainfall. Contrarily, the low-level factors such as extensive moisture advection, mid-tropospheric diabatic processes such as the latent heat release, daytime deep convection, and topographical impact of Zagros Mountains were found as the key factors leading to this system. This study also examines 11 different convection schemes simulated by the WRF model and verified against rainfall observation. The forecast skills of the output simulations suggest the Grell-Devenyi scheme as the superior configuration in simulating observed precipitation of the event over the area.  相似文献   

中层涡旋诱生南海热带低压形成的位涡反演分析     

袁金南  谷德军  廖菲 《高原气象》2015,34(1):93-102

利用NCEP 1°×1°最终分析资料FNL和位涡反演方法,对2006年8月下旬一次中层涡旋诱发南海热带低压的形成过程进行了分析。结果表明,在中层涡旋诱发南海热带低压形成时高层暖心结构经历了由上向下逐渐发展的过程,而中层气旋性环流经历了由上向下快速发展的过程。高层暖心结构的向下发展主要与中低层凝结潜热加热作用和干空气从高层侵入有关,而高层波动的影响不明显,暖心发展到达近海面需要有底层热力异常和中低层凝结潜热加热作用的共同配合。中层气旋性环流的向下发展主要与中低层凝结潜热加热作用有关,高层波动对中低层涡度的影响不明显,而底层热力异常主要在900 h Pa以下产生负涡度。综合分析表明,中低层凝结潜热加热对南海热带低压的生成和发展起关键作用。  相似文献   

准静止梅雨锋连续暴雨个例的位涡反演诊断   总被引：2，自引：4，他引：2  

赵玉春李泽椿  肖子牛谌芸 《气象学报》2007,65(3):353-371

2006年6月5—8日,受准静止的梅雨锋系统影响,福建北部地区发生了连续4 d的暴雨天气,引发了严重的洪涝灾害。文中利用1°×1°NCEP再分析资料、位涡诊断和位涡反演的方法,详细分析了梅雨锋演变过程中主要天气系统的变化,位涡和位涡扰动(位涡异常)与梅雨锋及梅雨锋带上强降水之间的关系,并通过分离位涡扰动的方法探讨了与不同物理过程有关的位涡扰动在梅雨锋发生发展中的作用。结果发现:对流层低层锋面南北两侧高压系统的稳定维持是准东西向梅雨锋形成和维持的主要原因。满足非线性平衡方程的平衡流很大程度上代表了实际气流,它的演变基本上反映了梅雨锋流场的演变。非平衡流形成了梅雨锋辐合带,它主要来自梅雨锋北侧的高压系统。与潜热释放有关的对流层中低层的正位涡扰动是梅雨锋发生发展中有主要影响的因子之一。边界层的位涡扰动一定程度上有利于梅雨锋的形成和维持。总体而言,下边界位温扰动并不利于梅雨锋的形成和维持,但它具有一定的日变化。高层位涡扰动对梅雨锋形成和维持的作用相对其他位涡扰动要弱的多,且不利于梅雨锋的形成和维持,但在梅雨锋后期南压阶段作用增强。对流层中低层与潜热释放无关的其他位涡扰动对梅雨锋的南压起到了一定作用。  相似文献   

大气运动的慢流形概论     

赵南  沈新勇  丁一汇 《地球科学进展》2007,22(4):331-340

从动力学系统的慢流形（slow manifold）的一般概念及数学描述出发，系统地论述了大气运动的慢流形的存在性和一般性质。文中侧重于讨论与大气运动的慢流形密切相关的一些重要问题，包括平衡运动或平衡流的性质以及它对惯性重力波的自发辐射（spontaneous emission）、PV反演理论和应用、与数值模式初始化问题的联系等，并对上述研究领域的研究历史和现状也进行了较为全面的综述，旨在为国内气象界相关方向的研究者提供了解该领域概貌并较快切入具体研究问题的线索。  相似文献   

气旋生成机制的位涡反演诊断   总被引：10，自引：2，他引：8  

周毅  寇正 《气象科学》1998,18(2):121-127

本文采用位涡反演方法,对一次西太平洋地区爆发性气旋的生成机制进行了诊断分析。结果表明：高层位涡扰动（即高空槽脊系统）所诱生的低层扰动风场特征为一支位于高空槽前下方的偏南气流,这支偏南气流是促使低层锋区扰动发展的主要动力因子：而低层位涡扰动（即低层锋区扰动）所诱生的低层扰动位势场和扰动风场是低层降压和气旋性环流生成的主要原因。  相似文献   

Integral spectroscopy of the nebula GM 1-29 and the star PV Cep     

T. A. Movsessian  T. Yu. Magakian  D. M. Sargsyan  E. H. Nikogossian 《Astrophysics》2008,51(3):387-393

Integral spectroscopy data for the nebula GM 1-29 and the source star PV Cep obtained on the 2.6-m telescope at the Byurakan Observatory are presented. The structure and kinematics of a collimated emission outflow directed along the axis of the nebula are studied. Changes in the radial velocity and intensity of the absorption component of the nebular Hα line are observed and studied; these are interpreted as a result of an anisotropy in the stellar wind at distances on the order of several stellar radii, where this absorption is formed. __________ Translated from Astrofizika, Vol. 51, No. 3, pp. 461–468 (August 2008).  相似文献   

ON THE RELATIONSHIPS BETWEEN THE UNUSUAL TRACK OF TYPHOON MORAKOT (0908) AND THE UPPER WESTERLY TROUGH     

费建芳  李波  黄小刚  程小平 《热带气象学报(英文版)》2012,18(2):187-194

In this paper,by carrying out sensitivity tests of initial conditions and diagnostic analysis of physical fields,the impact factors and the physical mechanism of the unusual track of Morakot in the Taiwan Strait are discussed and examined based on the potential vorticity(PV)inversion.The diagnostic results of NCEP data showed that Morakot’s track was mainly steered by the subtropical high.The breaking of a high-pressure zone was the main cause for the northward turn of Morakot.A sensitivity test of initial conditions showed that the existence of upper-level trough was the leading factor for the breaking of the high-pressure zone.When the intensity was strengthened of the upper-level trough at initial time,the high-pressure zone would break ahead of time,leading to the early northward turn of Morakot.Conversely,when the intensity was weakened,the breaking of the high-pressure zone would be delayed.Especially,when the intensity was weakened to a certain extent,the high-pressure zone would not break.The typhoon,steered by the easterly flow to the south of the high-pressure zone,would keep moving westward,with no turn in the test.The diagnostic analysis of the physical fields based on the sensitivity test revealed that positive vorticity advection and cold advection associated with the upper-level trough weakened the intensity of the high-pressure zone.The upper-level trough affected typhoon’s track indirectly by influencing the high-pressure zone.  相似文献   

The eclipsing binary PV Cas: a case of strong differential rotation in depth     

M. Y&#;ld&#;z 《Monthly notices of the Royal Astronomical Society》2005,363(3):967-976

In this study, we show that only models with differential rotation, as opposed to non-rotation or solid-body rotation for the components of PV Cas, are in satisfactory agreement with the observations (including constraints on the apsidal advance rate and the synchronous rotation of the components in addition to their luminosities and radii). Internal rotation profiles found for solar and metal-rich chemical compositions are similar to each other in that only a small part of the outermost regions is rotating very slowly  ( v _eq∼ 65 km s ⁻¹)  and the rest is rotating very rapidly. Confirmation of Ap-like variations in the light curve of the system leads us to search for a connection between this type (and similar types) of internal rotation and chemically peculiar stars. The temperature difference between the blue sides of the main sequence for the normal and for the magnetic Ap stars may arise from such a connection, since we find a similar difference between the models with this kind of rotation and the non-rotating models of somewhat lower mass.  相似文献   

光伏屋顶项目发电系统设计与分析     

王艳国 《中国勘察设计》2012,(1):81-83

基于建筑屋顶面积大、无遮阳等具有可利用光伏屋顶发电的有利条件,本文以山西某市职中校区内的建筑物为例,从气象条件、系统运行方式、光伏电池方阵设计及并网电气设计等方面提出了综合优化设计方案。  相似文献