山洪灾害监测雨量站网密度分析探讨   总被引：1，自引：1，他引：0  

舒大兴  韩金山 《水文》2011,31(5):64-67

暴雨是诱发山洪的主要原因,雨量监测站网的布设至关重要。本文采用抽站法和流域水文模型法对江西遂川江流域雨量站网密度进行了分析研究,得出允许误差控制下的最少监测站数量。对比分析站网密度公式计算结果,大流域内的子流域区划对雨量站数量有很大影响。综合考虑流域特征、地形起伏及流域内人口密度、社会经济水平等因素修正的站网密度公式,为无资料地区山洪监测预警系统建设提供参考。  相似文献   

ENSO事件对云南及临近地区春末初夏降水的影响   总被引：3，自引：0，他引：3       下载免费PDF全文

杨亚力  杜岩  陈海山 《大气科学》2011,35(4):729-738

本文采用合成及相关分析的方法,应用55年中国降水资料、美国NOAA海表温度资料以及NCEP/NCAR再分析资料,研究了ENSO事件对我国云南及其邻近地区春末初夏降水的影响及物理机理.研究结果表明:(1)在El Ni(n)o (La Ni(n)a)年,云南大部分地区4～5月降水偏少(多),东部地区相关信号尤其明显;(2)...  相似文献   

2010年浙南地区一次暴雨过程诊断分析   总被引：4，自引：0，他引：4       下载免费PDF全文

曹楚  王忠东 《气象与环境科学》2011,34(4):46-51

利用常规观测资料、中尺度自动站加密资料、多普勒雷达资料和NCEP1°×1°再兮析资料．对2010年5周8曲日发生在浙南的一次暴雨过程进行了诊断分析,结果发现：此次暴雨是在横槽转竖的大背景下,西风槽和高原槽东移合并加强,并在东移过程中与低层切变共同作用造成的;低空急流的形成在水汽的输送和聚集过程中发挥了重要作用;暴雨过程...  相似文献   

一个区域气候模式对ENSO衰减年夏季中国东部降水的模拟          下载免费PDF全文

ZENG Xian-Feng  LI Bo  FENG Lei  LIU Xiao-Juan  ZHOU Tian-Jun 《大气和海洋科学快报》2011,4(2):91-97

The performance of the Climate version of the Regional Eta-coordinate Model (CREM), a regional climate model developed by State Key Laboratory of Nu- merical modeling for Atmospheric Science and Geophysical Fluid Dynamics/Institute of Atmospheric Physics (LASG/IAP), in simulating rainfall anomalies during the ENSO decaying summers from 1982 to 2002 was evaluated. The added value of rainfall simulation relative to reanalysis data and the sources of model bias were studied. Results showed that the model simulated rainfall anomalies moderately well. The model did well at capturing the above-normal rainfall along the Yangtze River valley (YRV) during El Nio decaying summers and the below and above-normal rainfall centers along the YRV and the Huaihe River valley (HRV), respectively, during La Nia decaying summers. These features were not evident in rainfall products derived from the reanalysis, indicating that rainfall simulation did add value. The main limitations of the model were that the simulated rainfall anomalies along the YRV were far stronger and weaker in magnitude than the observations during El Nio decaying summers and La Nia decaying summers, respectively. The stronger magnitude above-normal rainfall during El Nio decaying summers was due to a stronger northward transport of water vapor in the lower troposphere, mostly from moisture advection. An artificial, above-normal rainfall center was seen in the region north to 35°N, which was associated with stronger northward water vapor transport. Both lower tropospheric circulation bias and a wetter model atmosphere contributed to the bias caused by water vapor transport. There was a stronger southward water vapor transport from the southern boundary of the model during La Nia decaying summers;less remaining water vapor caused anomalously weaker rainfall in the model as compared to observations.  相似文献   

Modeled Influence of East Asian Black Carbon on Inter-Decadal Shifts in East China Summer Rainfall   总被引：1，自引：0，他引：1       下载免费PDF全文

Rashed MAHMOOD  LI Shuang-Lin 《大气和海洋科学快报》2011,4(6):349-355

Two inter-decadal shifts in East China summer rainfall during the last three decades of the 20th century have been identified.One shift occurred in the late 1970s and featured more rainfall in the Yangtze River valley and prolonged drought in North China.The other shift occurred in the early 1990s and featured increased rainfall in South China.The role of black carbon(BC) aerosol in the first shift event is controversial,and it has not been documented for the second event.In this study,the authors used Geophysical Fluid Dynamics Laboratory's(GFDL's) atmospheric general circulation model known as Atmosphere and Land Model(AM2.1) ,which has been shown to capture East Asian climate variability well,to investigate these issues by conducting sensitive experiments with or without historical BC in East Asia. The results suggest that the model reproduces the first shift well,including intensified rainfall in the Yangtze River and weakened monsoonal circulation.However,the model captures only a fraction of the observed variations for the second shift event.Thus,the role of BC in modulating the two shift events is different,and its impact is relatively less important for the early 1990s event.  相似文献   

The Possible Mechanism of a Type of Vortex Heavy Rainfall during the Pre-Rainy Season in South China   总被引：2，自引：0，他引：2       下载免费PDF全文

LI Bo  LIU Li-Ping  ZHAO Si-Xiong 《大气和海洋科学快报》2011,4(5):247-252

In this paper,NCEP reanalysis data,intensive observation data collected from field experiment,model simulation data,and topographic trial data are fully analyzed to study a severe heavy rainfall event during 5 6 June 2008 in South China.Unlike most warm region rainfall cases,this one is associated with an obvious vortex system,which draws in water vapor and energy from the southwest monsoon surges ahead of a low trough above the Bengal Bay (BLT,Bengal Low Trough).At the lower troposphere,three currents,especially the southwest current and the east current,converge into the southeast of the vortex.Thus,the distributions of strong vorticity,water vapor,and ascending motion cause frequently occurrence and growth of convection there.The possible reasons for this rainfall event are summarized as a conceptual model.  相似文献   

南宁市蔗糖行业人工增雨服务效益调查评估     

罗伟  黄中雄 《气象研究与应用》2011,32(2):43-46

分析了南宁市种植甘蔗的气候适应性,以及降雨量与甘蔗生长、蔗茎产量及含糖量的关系,并对比分析了为南宁糖业股份有限公司所属蔗区实施人工增雨前后的甘蔗产量及蔗糖分,认为蔗糖分前后变化不大,但实施人工增雨后甘蔗产量有较显著提高,从而能获得令人满意的经济效益;在此基础上提出了做好人工增雨工作的改进思路。  相似文献   

Theoretical constraints to gully erosion research: time for a re‐evaluation of concepts and assumptions?     

Rafaello V. Bergonse  Eusébio J. Reis 《地球表面变化过程与地形》2011,36(11):1554-1557

Gullies are conceptualized in the literature as essentially fluvial forms with dimensional boundaries arbitrarily defined between rills and river channels. This notion is incompatible with the existing variability of form and process, as mass movements frequently exert a fundamental control on gully initiation and expansion, to the point of features outgrowing their original contributing area. The inability of a conceptual framework to incorporate existing observations inevitably constrains methodologies and research results. In this commentary, several examples of published results are contrasted with the prevailing assumption of an essentially fluvial nature, with the purpose of encouraging discussion on the need for a revised conceptual framework in gully erosion research. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Impact of subsurface rock fragments on runoff and interrill soil loss from cultivated soils   总被引：1，自引：0，他引：1  

T. Smets  M. López‐Vicente  J. Poesen 《地球表面变化过程与地形》2011,36(14):1929-1937

Field and laboratory studies have indicated that rock fragments in the topsoil may have a large impact on soil properties, soil quality, hydraulic, hydrological and erosion processes. In most studies, the rock fragments investigated still remain visible at the soil surface and only properties of these visible rock fragments are used for predicting runoff and soil loss. However, there are indications that rock fragments completely incorporated in the topsoil could also significantly influence the percolation and water distribution in stony soils and therefore, also infiltration, runoff and soil loss rates. Therefore, in this study interrill laboratory experiments with simulated rainfall for 60 min were conducted to assess the influence of subsurface rock fragments incorporated in a disturbed silt loam soil at different depths below the soil surface (i.e. 0.001, 0.01, 0.05 and 0.10 m), on infiltration, surface runoff and interrill erosion processes for small and large rock fragment sizes (i.e. mean diameter 0.04 and 0.20 m, respectively). Although only small differences in infiltration rate and runoff volume are observed between the soil without rock fragments (control) and the one with subsurface rock fragments, considerable differences in total interrill soil loss are observed between the control treatment and both contrasting rock fragments sizes. This is explained by a rapid increase in soil moisture in the areas above the rock fragments and therefore a decrease in topsoil cohesion compared with the control soil profile. The observed differences in runoff volume and interrill soil loss between the control plots and those with subsurface rock fragments is largest after a cumulative rainfall (P_cum) of 11 mm and progressively decreases with increasing P_cum. The results highlight the impacts and complexity of subsurface rock fragments on the production of runoff volume and soil loss and requires their inclusion in process‐based runoff and erosion models. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Surface circulation downstream of the Point Arena upwelling center     

Christopher M. Halle  John L. Largier 《Continental Shelf Research》2011,31(12):1260-1272

Measurements from recently installed 5 MHz high-frequency radar (CODAR) stations south of Point Arena, California, are used to describe surface current patterns during the upwelling season (June-August 2007). The systems provide hourly current maps on a 5-km grid, covering a region from approximately 10 to 150 km offshore (the continental shelf into the deep ocean). These HF-radar observations provide an unprecedented view of circulation in this “coastal transition zone”, between the wind-driven circulation over the shelf and the California Current circulation offshore. Circulation patterns include: (1) bifurcation of the coastal upwelling jet downstream of Point Arena into an along-shelf (down-coast) branch and an offshore branch, and (2) a large-scale anticyclonic meander that often develops into an eddy-like recirculation south of the bifurcation. The “recirculation” feature extends well offshore, with surface currents 50-100 km from the coast consistently opposing the wind stress. The spatial and temporal evolution of the surface current features during upwelling events affects surface transport from Point Arena to areas in the south, increasing the travel time of a substantial fraction of newly upwelled water from a few days to roughly two weeks. Thus, surface currents even far offshore influence coastal transport of nutrients, phytoplankton and larvae on ecologically relevant timescales, with resultant connectivity patterns very different than implied by a simple examination of the mean flow.  相似文献