温带气旋爆发性发展的中期背景及预报     

李晓东  马德贞 《气象》1993,19(5):34-38

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大兴安岭地区的一次暴雪天气诊断分析   总被引：1，自引：0，他引：1  

张桂莲  姚晓娟  孙永刚  孟雪峰  仲夏  刘文炜 《气象科技》2018,46(5):971-978

利用常规观测资料、FY-2气象卫星水汽云图、多普勒雷达资料、NCEP(1°×1°)逐6h再分析资料对2016年11月13—14日东北冷涡背景下的大兴安岭地区暴雪天气过程进行分析。结果表明:高空冷涡后部横槽南摆,使干冷空气南下以及冷涡前部西南低空急流北上且辐合急剧加强为暴雪天气提供了非常有利的环流背景;≥20m·s-1的西南低空急流作为水汽输送带,为暴雪区提供了充足的水汽来源;垂直上升运动中心和散度辐合辐散中心基本耦合且加强,为暴雪提供了强有利的动力抬升条件,有利于上升运动的增强发展;暴雪是发生在条件对称不稳定的(湿位涡MPV2<0)的背景下,暴雪中心位于MPV2等值线密集带以及MPV2绝对值得到较大增长的区域。水汽图像上有表征干侵入特征的干缝、斧形暗区等;雷达回波显示低层东南风急流非常显著,低层强烈发展的东南暖湿气流与东北—西南走向的大兴安岭山脉相垂直时,地形强迫抬升不仅使迎风坡的垂直上升运动迅速加强,而且使低层水汽辐合得到加强和维持为暴雪提供了充足的水汽,这也是暴雪主要集中在大兴安岭东麓的重要因素。  相似文献   

Asymmetric Relationship between the Meridional Displacement of the Asian Westerly Jet and the Silk Road Pattern     

Xiaowei HONG  Riyu LU  Shuanglin LI 《大气科学进展》2018,35(4):389-397

In previous work, a significant relationship was identified between the meridional displacement of the Asian westerly jet(JMD) and the Silk Road Pattern(SRP) in summer. The present study reveals that this relationship is robust in northward JMD years but absent in southward JMD years. In other words, the amplitude of the SRP increases with northward displacement of the jet but shows little change with southward displacement. Further analysis indicates that, in northward JMD years, the Rossby wave source(RWS) anomalies, which are primarily contributed by the planetary vortex stretching, are significantly stronger around the entrance of the Asian jet, i.e., the Mediterranean Sea–Caspian Sea area, with the spatial distribution being consistent with that related to the SRP. By contrast, in southward JMD years, the RWS anomalies are much weaker.Therefore, this study suggests that the RWS plays a crucial role in inducing the asymmetry of the JMD–SRP relationship.The results imply that climate anomalies may be stronger in strongly northward-displaced JMD years due to the concurrence of the JMD and SRP, and thus more attention should be paid to these years.  相似文献   

江苏一次大范围的爆发性强浓雾过程研究   总被引：7，自引：4，他引：3  

严文莲  朱承瑛  朱毓颖  刘端阳  濮梅娟 《气象》2018,44(7):892-901

利用江苏省70个自动观测站和365个交通气象观测站资料,对2016年2月11日夜间至12日上午出现在江苏的一次大范围强浓雾天气过程进行分析。结果表明:这次强浓雾过程具有爆发性形成和加强的特征,大部分站点从1000m以上快速下降形成强浓雾,且部分站点存在多次爆发增强现象;夜间天空打开,长波辐射降温作用加强,是大范围强浓雾形成和爆发性发展的一个重要原因;同时,雾前降雨为本次强浓雾的形成创造了基础条件,也是日出后部分站点由于水汽蒸发增强而导致雾爆发性增强的直接原因;另外,雾前和雾期间近地层强逆温的存在为雾的爆发性发展提供了稳定的大气层结条件,而逆温顶附近低空急流的形成,也一定程度上促进了逆温的维持和加强,利于雾的爆发性发展。  相似文献   

武警湖北省总队团职楼深基坑设计与施工          下载免费PDF全文

陈飞  黄晓琴 《探矿工程》2008,35(10):36-38,48

针对武警湖北省总队团职楼深基坑极为复杂的地质条件和周边环境,采用桩锚、锚喷网、放坡挂网喷砼和双排粉喷桩的联合支护方案,保证了基坑施工和周边建筑物及地下管线的安全,降低了工程成本,缩短了工期,取得了很好的经济效益和社会效益。  相似文献   

Predecessor Rain Events in the Yangtze River Delta Region Associated with South China Sea and Northwest Pacific Ocean (SCS-WNPO) Tropical Cyclones     

Huiyan XU  Xiaofan LI  Jinfang YIN  Dengrong ZHANG 《大气科学进展》2023,40(6):1021-1042

Predecessor rain events(PREs) in the Yangtze River Delta(YRD) region associated with the South China Sea and Northwest Pacific Ocean(SCS-WNPO) tropical cyclones(TCs) are investigated during the period from 2010 to 2019.Results indicate that approximately 10% of TCs making landfall in China produce PREs over the YRD region; however,they are seldom forecasted. PREs often occur over the YRD region when TCs begin to be active in the SCS-WNPO with westward paths, whilst the cold air is still existing...  相似文献   

Bias Analysis in the Simulation of the Western North Pacific Tropical Cyclone Characteristics by Two High-Resolution Global Atmospheric Models     

Qiyang LIU  Fengxue QIAO  Yongqiang YU  Yiting ZHU  Shuwen ZHAO  Yujia LIU  Fulin JIANG  Xinyu HU 《大气科学进展》2023,40(4):634-652

This study compares the atmosphere-only HighResMIP simulations from FGOALS-f3-H(FGOALS) and MRIAGCM3-2-S(MRI) with respect to tropical cyclone(TC) characteristics over the Western North Pacific(WNP) for the July–October months of 1985–2014. The focus is on investigating the role of the tropical easterly jet over the Western Pacific(WP＿TEJ) in modulating the simulation biases in terms of their climatological distribution and interannual variability of WNP TC genesis frequency(TCGF) based on the a...  相似文献   

Thermodynamics and Microphysical Characteristics of an Extreme Rainfall Event Under the Influence of a Low-level Jet over the South China Coast     

徐碧裕  黎慧琦  叶朗明  刘显通  饶晓娜  肖辉  徐加民  林青蒲义良  黄青兰 《热带气象学报(英文版)》2023,29(2):216-235

In this paper, the data of Automatic Weather Stations (AWSs), ERA5 reanalysis, sounding, wind profile radar, and dual-polarization radar are used to study an extreme rainfall event in the south China Coast on 11 to 12 May 2022 from the aspects of thermodynamics and microphysical characteristics under the influence of low-level jets (LLJs). Results show that: (1) The extreme rainfall event can be divided into two stages: the first stage (S1) from 0000 to 0600 LST on May 12 and the second stage (S2) from 0700 to 1700 LST on the same day. During S1, the rainfall is mainly caused by the upper-level shortwave trough and the boundary layer jet (BLJ), characterized by strong upward motion on the windward side of mountains. In S2, the combined influence of the BLJ and synoptic-system-related low-level jet (SLLJ) increases the vertical wind shear and vertical vorticity, strengthening the rainstorm. In combination with the effect of topography, a warm and humid southwest flow continuously transports water vapor to farther north, resulting in a significant increase in rainfall over the study area (on the terrain’s windward slope). From S1 to S2, the altitude of a divergence center in the upper air decreases obviously. (2) The rainfalls in the two stages are both associated with the mesoscale convergence line (MCL) on the surface, and the wind field from the mesoscale outflow boundary (MOB) in S1 is in the same direction as the environmental winds. Due to a small area of convergence that is left behind the MOB, convection moves eastward quickly and causes a short duration of heavy rainfall. In S2, the convergence along the MOB is enhanced, which strengthens the rainfall and leads to strong outflows, further enhancing the surface convergence near the MOB and forming a positive feedback mechanism. It results in a slow motion of convection and a long duration of heavy rainfall. (3) In terms of microphysics, the center of a strong echo in S1 is higher than in S2. The warm-rain process of the oceanic type characterizes both stages, but the convective intensity in S2 is significantly stronger than that in S1, featuring bigger drop sizes and lower concentrations. It is mainly due to the strengthening of LLJs, which makes small cloud droplets lift to melting levels, enhancing the ice phase process (riming process), producing large amounts of graupel particles and enhancing the melting and collision processes as they fall, resulting in the increase of liquid water content (LWC) and the formation of large raindrops near the surface.  相似文献   

海南岛不同强弱秋汛期暴雨的环流形势和动力特征分析     

冯文  吴俞  赵付竹  周玲丽 《气象科学》2017,37(6):784-796

基于天气学诊断分析方法,对2000年10月11—14日、2010年10月1—8日和2003年10月4—5日、2005年10月10-11日4次不同降水强度的秋汛期暴雨过程进行了对比分析,研究结果表明:不同强度秋汛期暴雨过程的降水分布和高低层天气系统配置具有相似性,导致秋汛期暴雨出现强度差别的主要原因是天气系统强度、位置的差异。秋汛期暴雨强个例中,南亚高压中心位于海南岛上空,辐散强度是弱个例的2~3倍,南海热带低值系统相对更强,位置偏北,副高偏弱主体退缩至海上。南海中北部出现偏东风低空急流是秋汛期暴雨过程中最显著的环流特征。在不同强度的降水个例中,急流的分布形态、强度存在明显差别。强个例中低空急流的急流核强度、长度、厚度,以及急流核上方的风速梯度均远大于弱个例,且水平风随高度顺时针旋转现象十分显著,出现强的暖平流。此外,最强降水日中强个例的低空急流核位于海南岛东部近海上空,在水平方向上稳定少动,垂直方向和风速上则脉动剧烈。弱个例的急流核在水平方向上东西振荡明显,在垂直高度和风速上变化很小。秋汛期暴雨强个例的水汽主要由偏南风、偏东风和东北风3支气流输送而来,既有经向输送也有纬向输送,弱个例的水汽以经向输送为主,多为偏东气流所致。  相似文献   

不同区域海温对亚洲夏季副热带西风急流变异主模态的影响   总被引：3，自引：2，他引：1  

李笛  陈海山 《气象科学》2017,37(4):425-435

利用1979—2014年ERA Interim再分析资料和NCAR CAM5.1大气环流模式,围绕海温对夏季亚洲急流变异主模态的影响展开研究。首先通过理论分析和动力诊断方法,对急流主模态的物理特征进行分析,并证实了海温与急流变异的显著联系。随后基于观测结果设计数值试验方案,探究不同区域海温对急流演变的具体贡献。结果表明,急流第一模态与太平洋及印度洋异常海温紧密联系,在二者相似的贡献下,高层异常风场表现为沿急流轴线南北偏移的纬向对称分布;急流第二模态的上、下游风场则受到不同海表热源影响,在印度洋、太平洋及北大西洋异常海温的协同作用下,亚洲上空形成了四极型纬向非对称的风场分布。该结果有利于更加综合地认识亚洲夏季副热带急流的变异特征,也为研究海温对急流的影响效应提供了新的依据。  相似文献