Methodology to set trigger levels in an urban drainage flood warning system – an application to Jhonghe,Taiwan     

Hsiang-Kuan Chang  Jihn-Sung Lai 《水文科学杂志》2018,63(1):31-49

A wireless water-level monitoring system for an urban drainage flood warning is developed, and stations equipped with pressure sensors are installed to monitor water levels. The water levels for flood warning are investigated. Two stages of warning water level for “larger” conduits are set based on the rate of rising water levels. In a similar way, only one stage of the warning water level is set for “smaller” conduits. The average rates of rising water levels for different scenarios are estimated using the US EPA Storm Water Management Model (SWMM). When evaluating the impact of flooding, the outflows from manholes simulated by the SWMM are used as sources for a two-dimensional overland flow simulation. The integrated system is successfully executed in Jhonghe, New Taipei City, Taiwan, which has experienced urban drainage floods. Therefore, this system can provide urban drainage flood warnings to the authorities to take disaster reduction measures.  相似文献   

Convection in an internally cooled fluid layer heated from below     

T. Hartlep  F. H. Busse 《地球物理与天体物理流体动力学》2018,112(1):20-35

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一次暴雨过程受不同系统影响的动力热力场结构特征     

任丽  关铭  李有缘  王深义 《气象科技》2019,47(6):959-968

本文使用常规观测资料、卫星云图、自动气象站降水量以及0.25°×0.25°的NCEP/NCAR再分析资料,对出现在东北地区北部受不同系统影响的连续2d暴雨过程的热力和动力场结构特征展开研究。结果表明:24日为暖锋锋生暴雨,暴雨范围大;25日为台风暴雨,暴雨出现在台风移动路径上,为狭长带状。暴雨是由MCS活动造成的,每次短时强降水均与TBB低值中心相对应,台风倒槽内的MCS强度比暖锋云系内的MCS弱,但是降水强度却更大。台风安比携带大量暖湿空气,其东侧的低空急流向北输送热量和水汽,水汽辐合集中在边界层内,台风暴雨的水汽辐合强度比暖锋暴雨更强烈,所造成的雨强更大。暖锋暴雨期间,小兴安岭迎风坡地形的辐合抬升作用明显;高层强辐散及地形辐合抬升作用对暴雨有较大贡献。台风暴雨期间,低空辐合,特别是水汽辐合作用对暴雨有较大贡献;辐合区位于台风倒槽附近,倒槽表现为冷锋性质。  相似文献   

Contribution of dendrogeomorphology to the dating of secondary processes on dormant rockslides     

《Quaternary Geochronology》2022

Rockslides in the Variscan orogenic belt of the Central Europe are a rare and poorly studied phenomenon. These relatively stable features have recently been shaped by secondary rockfall, toppling, sliding, or slumping. On afforested slopes, such processes can be efficiently analysed and dated by dendrogeomorphic methods. We performed detailed analyses of 355 increment cores from 81 Picea abies (L.) Karst. trees growing on two dormant rockslides in northeastern Czechia to reconstruct the activity of rock block movements and rockfalls. For the event determination we used standard event-response (I_t) index and a semi-quantitative approach involving logical spatial position of disturbed trees during a three-year period. Furthermore, climate preparatory and triggering factors were analysed to investigate possible main drivers of recent secondary processes. Overall, four periods of certain block reactivations at the Prudký site since 1940 and seven periods of certain block reactivations at the Rudohorský site since 1834 were reconstructed. Most of the events can be dated to the period 1960–2000, but our data do not indicate any high-magnitude activity. This paper also demonstrates the results of tree eccentric growth not only in the main supposed direction of stem tilting but also in the direction perpendicular to the main direction when ca. 40% of all trees growing on rock blocks recorded the movements in both analysed axes of stem tilting, suggesting possible complex deformation and different directions of block movements over time. It also appeared that the periods with greatest activity of secondary movements were characterised by a significantly higher rain-on-snow factor (p = 0.007 and 0.026 at the Prudký and the Rudohorský site, respectively) thus indicating block detachments during periods of rapid snowmelt.  相似文献   

2017年6月一次华南沿海强降水的对流性特征及热动力机制研究          下载免费PDF全文

曾智琳  谌芸  朱克云 《大气科学》2019,43(6):1295-1312

在华南北部或长江流域有锋面雨带活动时,华南沿海常常会出现对流性强降水,突发性很强,给预报造成很大的困惑。文章采用多种观测资料、ERA-Interim 0.125°×0.125°逐6 h再分析资料,对2017年6月15～16日华南北部的锋面雨带及沿海强降雨过程开展分析,对比了二者降水特征与环境条件,重点探讨了该次过程华南沿海强降雨的对流触发与维持,揭示了一种由边界层风切变强迫造成涡度持续发展的动力效应。结果表明:（1）锋面雨带与华南沿海强降雨在降水特征上有显著差异,并各有特点。锋面雨带以大尺度层状云降水和弱对流性降水为主,降水强度东段弱西段强。沿海强降雨以对流性降水为主,局地性强、落区集中、强降雨持续时间长、夜发性明显。（2）水汽方程诊断发现沿海强降雨在边界层水平水汽平流项、垂直水汽输送项比锋面雨带东段具有更大量级,大气层结反映出更深厚的暖层、湿层与对流不稳定,是二者降水强度及性质差异的主要原因。（3）莲花山、峨眉嶂造成气流侧向摩擦与正面阻挡促使漯河河谷内垂直涡度发展,暖湿空气堆积上升并达到自由对流高度,触发了华南沿海最初的降水。夜间建立的西南风急流使边界层垂直风速切变增强,水平涡度倾斜部分转化为垂直涡度发展,与风速水平切变造成的垂直涡度叠加,是强降雨持续时间长的动力机制。海陆边界摩擦差异造成水平、垂直两个方向的风切变增强,共同强迫垂直涡度发展是此次强降雨过程对流维持的动力效应。（4）方程诊断表明华南沿海强降雨由对流潜热释放造成的垂直上升速度占总垂直上升速度的39%～75%,持续、稳定的对流潜热释放是强降雨持续时间长的热力驱动因素。  相似文献   

On the linkage between changes in cloud cover and precipitation extremes over Central India     

《Dynamics of Atmospheres and Oceans》2019

In this study, linkage between changing characteristics of precipitation extremes and cloud covers over Central India is explored during summer monsoon period using Satellite data (1998–2015). This is a first attempt to relate the changes in cloud cover to the changes in precipitation extremes. Non-rainy cirrus clouds are excluded from this study. Results show that heavy rainfall (≥ 60 mm/day) is associated with cold cloud tops (Tb≤220 K) while moderate rainfall (<60 mm/day and ≥20 mm) occurs mostly with middle clouds (Tb>220 K and ≤245 K). Low level clouds (Tb> 245 K) are responsible for light rainfall (<20 mm/day). Increases in top 20%, 10%, 5% and 1% heavy precipitation relate well with the increases in very deep convective, deep convective and convective cloud cover. Among these relations, increase in top 5% heavy precipitation relates best with increase in very deep convective cloud cover. Decrease in bottom 30% low precipitation relates with decrease in low level cloud cover. The results reported in this study fit into the framework of how weather extremes respond to climate change.  相似文献   

Volcanism Pacing Slumping Gravity Flow Deposits during the Late Carboniferous in the Southern Margin of the Junggar Basin,China     

LI Shixin  ZHANG Tingshan  ZHANG Xi  LIANG Zeliang  JI Dongsheng  Mihai Emilian POPA  YONG Jinjie  LUO Jinyu  ZENG Jianli  ZHU Haihua 《《地质学报》英文版》2023,97(5):1422-1450

Deep-water gravity depositional processes and evolution in arc systems have become topics of intense research focus in recent years. This study discusses the co-evolution of volcanism and deep-water gravity flow deposits at the southern margin of the Junggar Basin, based on petrology, geochronology and geochemical analyses. The results show that a massive collapse of unstable sediments from the slope was triggered by volcanism, resulting in the formation of slumping gravity flows. The occurrence...  相似文献   

基于时态数据库技术的导航信息空间关系局部动态更新方法     

郭继发  毛健  崔铁军 《测绘软科学研究》2011,(4):47-50

针对目前导航电子地图生产中导航地图数据生产周期长的问题,提出了一种基于导航数据生命周期状态维护触发器的导航地图数据生产时空动态更新模型。首先基于时空数据库技术构建了导航地图数据生产时空数据模型,构建了导航数据生命周期状态维护触发器,将导航数据空间关系分为一级几何拓扑和二级逻辑拓扑。利用触发器,使得导航数据的任何变更（几何和逻辑）得到有效记录,保证了增量包的有效导出。  相似文献   

基于BJ-RUC系统的临近探空及其对强对流发生潜势预报的指示性能初探   总被引：19，自引：12，他引：7  

陈敏  范水勇  郑祚芳  仲跻芹 《气象学报》2011,69(1):181-194

缺乏对流天气发生临近时刻的探空观测资料是制约强对流短时预报水平进一步发展的重要因素.随着数值预报技术水平的持续提高,高时空分辨率数值预报输出的模式探空性能越来越好,这为获取对流发生前的临近探空提供了有益的补充.本文针对北京地区2008年夏季20次较强的对流过程,得出北京市气象局BJ-RUC数值预报系统输出的54511站在分析时次(t=0)和预报时效分别为3和6 h的预报偏差均略差于t=0的分析探空,但是此两个时次的预报探空误差仍然处于可接受的范围内.对比20个对流个例54511站分别基于观测和分析或预报的对流不稳定能量、水平风的垂直切变等基本对流参数可以发现t=0时次模式分析探空在趋势和量级上与基于实际探空观测诊断的对流参数均有较好的一致性,基本上能够较为正确地在模式中反映临近对流发生前实际大气的环境特征;但是当考虑实际的预报时效时,t=3和6 h的预报探空能够提前约1和4 h为预报员提供对未来对流发生潜势预报的判断.因此,此两个时次探空更具有实际的业务应用价值.以两个强对流个例为例分析了BJ-RUC系统提供的分析和预报临近探空的性能及其对强对流潜势预报的指示性作用.结果表明,BJ-RUC输出的分析和预报探空对未来对流发生潜势具有较好的指示作用.但依据模式输出的探空变化要对对流发生时间、强度、落区乃至对流类型进行准确预报仍有一定的难度.  相似文献   

风廓线雷达资料在一次强对流天气过程中的应用   总被引：2，自引：0，他引：2  

林中庆  曹亚平  赵小伟 《气象研究与应用》2011,32(3):19-22,120

通过分析2010年6月28日广州市南沙区强对流天气过程的风廓线雷达资料发现：风廓线雷达测得的温度廓线资料可以很直观地显示边界层逆温及高温区域随时间的变化;风廓线雷达产品（垂直速度和信号噪声比）能清楚地反映降水的开始、结束以及降水的强度;风廓线雷达可以很好的监测到低空急流的发生发展及水平风的垂直切变．对强对流天气的预报有...  相似文献