秭归暴雨与水文特征分析   总被引：1，自引：0，他引：1  

梁季阳 《地理研究》1995,(4)

三峡水库淹没区移民后撤安置，可能引起库区地表水上状态的变化，暴雨是水土流失的主要动力因素。本文分析了库区秭归一带的年降雨的时间分配，暴雨的时间与空间分布的强烈不均匀的特征；论述了有关水文要素，如流域蒸散发、土壤含水量等。最后对王家桥小流域进行了暴雨径流模拟。  相似文献   

1986年2月特大电离层暴的动力学表现     

苏元智  黄信榆 《地球物理学报》1989,32(5):507-515

1986年2月的太阳耀斑爆发导致了强烈的磁暴和电离层暴。 对我国多个台站有关电离层观测记录的分析表明:这次电离层暴呈现出显著的纬度效应,井在武昌、广州等地区形成了明显的“暴中心”。在暴变期间,伴随有大尺度的TID。在某些时段内,F区电子密度剖面产生了特殊的畸变。 对暴变形态特征及其形成机制进行了一些初步讨论。  相似文献   

Recession curve estimation for storm event separations     

M. Hammond  D. Han   《Journal of Hydrology》2006,330(3-4):573-585

An accurate recession curve model is important for separating individual flow events, which is especially difficult over catchments in regions with a maritime climate where frequent rainfall events cause the flows to rise before they reach the baseflow level. The traditional recession curve equations are based on static linear and nonlinear reservoir models. These models work quite well for ground water dominated recession curves, but not so well when the direct runoff is significant in the recession part. In this study, a new modelling methodology is explored based on self-adaptive parameters in the linear and nonlinear reservoir models. It has been found that the adaptive forms performed better than the static ones, especially when a window for the adaptive parameter estimation is properly selected. While the nonlinear adaptive model had better accuracy over the linear one, it could become unstable if its window is too narrow, indicating that more research work is needed to find an useful pattern for the window size. A comparison between the recession curve models and PDM model (a rainfall-runoff model) has shown that they agreed quite well in most winter events, but less so in the summer.  相似文献   

南沙群岛永暑礁澙湖沉积的晚全新世风暴事件记录   总被引：1，自引：0，他引：1  

施祺  余克服 《热带地理》2007,27(1):1-5

位于南沙群岛永暑礁西南小澙湖的南永4井岩芯柱中含多层珊瑚枝和珊瑚砾石的堆积,反映了突发性风暴事件造成的珊瑚碎屑快速搬运和堆积。全新世晚期约4 000 aBP以来,澙湖珊瑚砾堆积记录了1 400870BC、660BC390AD、600770AD和940-1992AD 4个主要的风暴事件频发时期,并且风暴的强度呈阶段性增强。风暴事件还表现出千年和百年尺度的周期性波动,具有1 280 a、370 a、210230 a、140150 a和90 a的准周期,与全新世气候环境的周期性变化相对应,很大程度上受太阳活动周期变化的影响。  相似文献   

The dependence of UK extreme sea levels and storm surges on the North Atlantic Oscillation     

P.L. Woodworth  R.A. FlatherJ.A. Williams  S.L. WakelinS. Jevrejeva 《Continental Shelf Research》2007

The role of the North Atlantic Oscillation (NAO) in effecting changes in winter extreme high and low waters and storm surges in UK waters has been investigated with the use of a depth-averaged tide+surge numerical model. Spatial patterns of correlation of extreme high and low waters (extreme still water sea levels) with the NAO index are similar to those of median or mean sea level studied previously. Explanations for the similarities, and for differences where they occur, are proposed. Spatial patterns of correlations of extreme high and low and median surge with the NAO index are similar to the corresponding extreme sea-level patterns. Suggestions are made as to which properties of surges (frequency, duration, magnitude) are linked most closely to NAO variability. Several climate models suggest higher (more positive) average values of NAO index during the next 100 years. However, the impact on the UK coastline in terms of increased flood risk should be low (aside from other consequences of climate change such as a global sea-level rise) if the existing relationships between extreme high waters and NAO index are maintained.  相似文献   

一次远距离台风暴雨过程的熵流指数演变   总被引：1，自引：10，他引：1  

张霞  王咏青  符长锋  周建群 《气象科学》2007,27(5):522-529

应用耗散结构理论,结合河南省一次远距离台风暴雨过程,分析了大气排熵指数、边界层上部广义相当位温及广义相当位温平流等三个熵流指数与暴雨的发生和落区的关系,得到:大气排熵指数由高值向低值的演变有利于对流的发展,从而导致对流暴雨形成;暴雨落在大气排熵指数负值中心或负值轴线附近区域;远距离台风暴雨产生前,有高熵空气在边界层上部聚集,边界层高熵中心往往与暴雨落区对应;边界层上部高熵平流的移向往往预示了强降水的未来移向。  相似文献   

基于数学形态学的三维风暴体自动识别方法研究   总被引：1，自引：1，他引：1  

韩雷  郑永光  王洪庆  林隐静 《气象学报》2007,65(5):805-814

基于雷达数据的风暴体识别、追踪及预警方法是重要的临近预报技术之一,其中准确的风暴体自动识别是进行风暴体自动追踪和预警的前提。在风暴体识别中常会碰到的两个问题是:虚假合并和从风暴簇中分离出相距较近的风暴单体。美国国家大气科学研究中心提出的TITAN(Thunderstorm Identification,Tracking,Analysis,and Nowcasting)算法使用单阈值进行识别,容易将相邻的多单体回波识别为一个风暴体。美国国家强风暴实验室提出的SCIT(Storm Cell Identification and Tracking)算法使用7个反射率因子阈值进行识别,可以较好地分离出风暴簇中的风暴单体,但它直接抛弃了低阈值的识别结果,导致风暴体内部结构信息的丢失。SCIT的这种识别策略可能会使处于初生阶段、强度较低的风暴体被错误地抛弃掉。TITAN和SCIT都无法完全识别出相邻风暴的虚假合并。为了解决这两个问题,文章提出了基于数学形态学的识别方法。该方法首先使用第1级阈值进行单阈值识别;其次,对识别得到的风暴体执行基于动态卷积模板的腐蚀操作,以消除虚假合并;然后,使用高一级阈值进行识别,并对识别得到的风暴体进行膨胀操作,当风暴体的边界在膨胀的过程中相互之间接触,或接触到了原来较低阈值识别的风暴体的边界时,则停止膨胀过程;最后,逐次使用更高级别的阈值进行识别,并在每一级阈值的识别过程中执行腐蚀和膨胀操作。试验结果表明,通过在多阈值识别的过程中综合使用膨胀和腐蚀操作,基于数学形态学的三维风暴体识别方法不仅能够成功地识别出风暴体的虚假合并,同时还能在从风暴簇中分离出相距较近的风暴单体时,尽可能多地保留风暴单体的内部结构信息。  相似文献   

CAM3.0模式中北大西洋风暴轴对“三核型”海温异常的响应     

曾鼎文  李耀辉  张文波  苟尚 《干旱气象》2015,(1):70-77

为了探究冬季(12~2月)北大西洋地区风暴轴与海温异常的关系,利用伴随AO(Arctic Oscillation)出现的"三核型"海温异常对大气环流模式CAM3.0进行强迫,将模拟结果与NCEP/NCAR再分析资料做对比,发现CAM3.0在该SSTA强迫下可以再现伴随AO异常出现的风暴轴与急流异常,结论可概括为:海温正(负)异常时,北大西洋风暴轴增强(减弱),北美急流出口区向北(向南)摆动;"三核型"海温异常作为外强迫源,可能通过2种途径影响风暴轴的强度:首先通过热力作用改变中纬度低层大气斜压性来直接影响风暴轴,其次通过影响北美急流出口区的南北摆动来间接影响风暴轴;另外,海温正(负)异常可以增强(减弱)瞬变波与基本气流之间的正反馈效应。  相似文献   

Neural network prediction of a storm surge   总被引：4，自引：0，他引：4  

T.-L. Lee   《Ocean Engineering》2006,33(3-4):483-494

The occurrence of storm surge does not only destroy the resident's lives, but also cause the severe flooding in coastal areas. Therefore, accurate prediction of storm surge is an important task during the coming typhoon. Conventional numerical methods and experienced methods for storm surge prediction have been developed in the past, but it is still a complex ocean engineering problem which many factors, including the central pressure of typhoon, the speed of the typhoon, the heavy rainfall, coastal topography and local features influence the variation of storm surge. In fact, this problem is still a complex nonlinear relationship that can not solved efficiently by these two methods. Therefore, this paper presents an application of the neural network for forecasting the storm surge. The original data of Jiangjyun station in Taiwan will be used to test the performance of the present model. The results indicate that the neural network can be efficiently forecasted storm surge using the four input factors, including the wind velocity, wind direction, pressure and harmonic analysis tidal level.  相似文献   

渤海局部海域风暴潮漫滩计算模式──ADI干湿网格模式在渤海局部海域风暴潮漫滩计算中的应用   总被引：1，自引：0，他引：1  

吴巍  孙文心 《中国海洋大学学报(自然科学版)》1995,(2)

采用ＡＤＩ干湿网格模式和一种大小区嵌套式的数值计算格式，考虑了天文潮与风暴潮的非线性耦合效应，对渤海局部海域的风暴潮漫滩进行了数值模拟。模拟结果与实测结果符合良好，证实ＡＤＩ干湿网格模式对海湾风暴潮漫滩计算的可行性。指出ＡＤＩ干湿网格模式对预报淹水受灾范围具有应用价值。  相似文献