Mechanisms and pathways of lateral flow on aspen‐forested,Luvisolic soils,Western Boreal Plains,Alberta, Canada     

Todd Redding  Kevin Devito 《水文研究》2010,24(21):2995-3010

Rainfall simulation experiments by Redding and Devito ( 2008 , Hydrological Processes 23: 4287–4300) on two adjacent plots of contrasting antecedent soil moisture storage on an aspen‐forested hillslope on the Boreal Plain showed that lateral flow generation occurred only once large soil storage capacity was saturated combined with a minimum event precipitation of 15–20 mm. This paper extends the results of Redding and Devito ( 2008 , Hydrological Processes 23: 4287–4300) with detailed analysis of pore pressure, soil moisture and tracer data from the rainfall simulation experiments, which is used to identify lateral flow generation mechanisms and flow pathways. Lateral flow was not generated until soils were wet into the fine textured C horizon. Lateral flow occurred dominantly through the clay‐rich Bt horizon by way of root channels. Lateral flow during the largest event was dominated by event water, and precipitation intensity was critical in lateral flow generation. Lateral flow was initiated as preferential flow near the soil surface into root channels, followed by development of a perched water table at depth, which also interacted with preferential flow pathways to move water laterally by the transmissivity feedback mechanism. The results indicate that lateral flow generated by rainfall on these hillslopes is uncommon because of the generally high available soil moisture storage capacity and the low probability of rainfall events of sufficient magnitude and intensity. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

绝对加速度反馈主动控制     

刘晖  唐家祥 《世界地震工程》2001,17(1):36-39

利用绝对加速度测量简单、可靠的特点，提出了一种新的反馈控制方法，即基于绝对加速度的反馈控制算法。同时，考虑到驱动器的时滞，发展了考虑察动器时滞的结构状态方程。实例研究表明，该方法改善了时滞的影响，具有良好的控制效果。  相似文献   

隧道工程地质预报方法探讨   总被引：32，自引：1，他引：32  

丁恩保  马继平 《工程地质学报》1995,3(1):28-34

本文从一些隧道工程事故实例出发，讨论了引起坍方和涌水灾害的工程、水文地质条件，不同工程阶段的预报方法以及预报研究的重大经济效益。最后提出五点提高预报符合率的原则和方法。  相似文献   

夏季副热带中——中间尺度系统发展的一种机制     

陈忠明 《大气科学》1993,17(6):756-761

本文研究了夏季副热带中—中间尺度天气系统的发展问题,结果表明,在潮湿不稳定大气中,扰动与凝结释热之间的正反馈过程是系统初期发展的一种机制,非线性作用将抑制系统的无限发展,使之发展到一定强度后即处于稳定状态。  相似文献   

具有门限的一种非线性随机-动力模式   总被引：3，自引：0，他引：3       下载免费PDF全文

丁裕国  江志红 《热带气象学报》1993,9(2):97-104

提出一种附加门限控制的具有非线性反馈作用的随机-动力模式,从而对具有线性反馈的随机-动力气候模式加以改进。从理论上说,这种具有门限的随机气候模式可使气候系统内部反馈机制中的非线性特征更为明显,以便更加客观地模拟和预报短期的气候变化。  相似文献   

THE MEANDER OF KUROSHIO AND OSCILLATION IN A COUPLED OCEAN-ATMOSPHERE MODEL^*          下载免费PDF全文

Liu Qinyu  Xu Qichun  Wang Zhilian  Qin Zenghao 《Acta Meteorologica Sinica》1993,7(3):338-346

A numerical experiment of an asynchronous coupled ocean-atmosphere model has been described in this paper.A two-layer global atmosphere general circulation model(OSU/IAP-AGCM)and a two-layer North Pacific Ocean general circulation model(NPOGCM) developed by Liu et al.(1992)are used in numerical experiment.The sea surface temperature anomaly(SSTA) corresponding to the meander of the Kuroshio is treated as the initial perturbation in the Pacific Ocean and the abnormal phenomena caused by the disturbance and the interaction between atmosphere and ocean,have been studied.The numerical experiment showed that the SST anomaly in the North Pacific could induce a new 30-60 day osciltation through the coupling between atmosphere and ocean and the interaction between the meander of the Kuroshio and atmosphere circulation is a positive feedback process.  相似文献   

不同暴雨系统中潜热反馈作用的对比研究     

潘在桃  王作述  蔡则怡 《热带气象学报》1994,10(2):161-171

选择两种类型的暴雨个例用数值试验研究了不同条件下潜热反馈作用的大小，结果发现对于不同的暴雨系统，潜热作用差别很大，“６２６”（１９８６年６月２６日）京津冀暴雨中它使雨量增加约一倍，而“７５８”（１９７５年８月７日）河南暴雨却增加约四倍。此外，潜热反馈对高低空急流强度、位置，以及对上升运动大小的影响程度，也都是在“７５８”暴雨过程中较大。数值试验证明了造成这种差别的重要原因是高空急流强度和风速铅直切  相似文献   

基于序列影像的飞机姿态跟踪测量方法研究   总被引：21，自引：2，他引：21  

张祖勋  苏国中  张剑清  郑顺义 《武汉大学学报(信息科学版)》2004,29(4):287-291

探讨了一种基于序列影像的飞机姿态获取方法。基于这些影像和运动轨迹 ,从摄影测量和投影几何的角度出发 ,深入探讨了利用序列影像对空中飞行的目标进行姿态跟踪测量的方法 ,并提出了利用广义点反馈迭代的最小二乘方法 (parapointfeedbackiteration ,PFI)和模拟影像与真实影像匹配的目标姿态跟踪求解方案。  相似文献   

Rift zone reorganization through flank instability in ocean island volcanoes: an example from Tenerife, Canary Islands     

T. R. Walter  V. R. Troll  B. Cailleau  A. Belousov  H.-U. Schmincke  F. Amelung  P. v.d. Bogaard 《Bulletin of Volcanology》2005,67(4):281-291

The relationship between rift zones and flank instability in ocean island volcanoes is often inferred but rarely documented. Our field data, aerial image analysis, and ⁴⁰Ar/³⁹Ar chronology from Anaga basaltic shield volcano on Tenerife, Canary Islands, support a rift zone—flank instability relationship. A single rift zone dominated the early stage of the Anaga edifice (~6–4.5 Ma). Destabilization of the northern sector led to partial seaward collapse at about ~4.5 Ma, resulting in a giant landslide. The remnant highly fractured northern flank is part of the destabilized sector. A curved rift zone developed within and around this unstable sector between 4.5 and 3.5 Ma. Induced by the dilatation of the curved rift, a further rift-arm developed to the south, generating a three-armed rift system. This evolutionary sequence is supported by elastic dislocation models that illustrate how a curved rift zone accelerates flank instability on one side of a rift, and facilitates dike intrusions on the opposite side. Our study demonstrates a feedback relationship between flank instability and intrusive development, a scenario probably common in ocean island volcanoes. We therefore propose that ocean island rift zones represent geologically unsteady structures that migrate and reorganize in response to volcano flank instability.Editorial responsibility: T. DruittThis revised version was published online in February 2005 with typographical corrections and a changed wording.  相似文献   

The Effect of Orography on Evaporation     

C. Huntingford  E. M. Blyth  N. Wood  F. E. Hewer  A. Grant 《Boundary-Layer Meteorology》1998,86(3):487-504

The effect of orography on the spatial variability of surface evaporation is studied numerically for two hill heights and two prescribed forms of surface resistance. A numerical model of the planetary boundary layer carrying scalars of temperature and specific humidity, and with a surface energy balance scheme, is employed. It is found that the difference in mean evaporation between model runs with hills and analogous runs for flat terrain may be explained primarily by an increase in surface area and adiabatic cooling at the hill surface.  相似文献