Modelling Extreme Storm-Induced Currents over the Grand Banks     

Yongsheng Wu  Charles C.L. Tang  Michael Z. Li  Robert H. Prescott 《大气与海洋》2013,51(3):259-268

Abstract

The wind climate of the mountainous terrain in the southern Yukon is simulated using the Wind Energy Simulation Toolkit (WEST) developed by the Recherche en Prévision Numérique (RPN) group of Environment Canada and is compared to measurements in the field. WEST combines two models that operate at different spatial scales. The Mesoscale Compressible Community (MC2) model is a mesoscale numerical weather prediction model that produces simulations over large domains of the order of a thousand kilometres. The MC2 model uses long‐term synoptic scale wind climate data from the analysis of radiosonde and other observations to simulate mean wind fields at tens of metres above the ground using a horizontal resolution of a few kilometres. The mesoscale results are used as input to MS‐Micro/3 (Mason and Sykes (1979) version of the Jackson and Hunt (1975) model version for microcomputers/3‐dimensional; MS‐Micro hereafter), a more computer‐efficient, microscale model with simpler linearized momentum equations and a domain restricted to a few tens of kilometres with horizontal grid sizes of tens or hundreds of metres. MS‐Micro provides wind field results at specific wind generator hub heights (typically 30 to 50 m above ground level (AGL)) which are of interest to researchers and developers of wind farms.

WEST shows relatively strong correlations between its simulated long‐term mean wind speed and the measurements from ten wind energy monitoring stations. However, in the mountainous terrain of the Yukon, WEST tends to predict wind speeds which are about 40% too high. The model also produces erroneous wind directions and some were perpendicular to valley orientations. The most likely cause of the wind speed and direction errors is the substantially modified 5‐km grid‐spaced mesoscale terrain used in MC2. The WEST simulation was also found to double the wind speeds observed at airport stations and there was poor correlation between the simulated and observed wind speeds.

The bias in the model could be attributed to a number of factors, including the use of smoothed topography by the model, the discrepancy between the neutral atmosphere assumed in MS‐Micro and the normally observed stable atmosphere, the application of MS‐Micro to every third grid point of the MC2 output, abnormally high sea level wind speeds in the input climate data for MC2, and a certain degree of disagreement between the land surface characteristics used in the model and those found in the field.

At comparatively low computer cost, WEST predicts a wind climate map that compares favourably to the wind measurements made in several locations in the Yukon. However, the problem of the modified terrain in the mountainous regions is the most pressing problem and needs to be addressed before WEST is used in the mountainous regions of Canada.  相似文献   

江南运河水文情势变化分析   总被引：2，自引：0，他引：2       下载免费PDF全文

吴娟  林荷娟  武剑  季同德 《水文》2018,38(4):78-82

随着太湖流域城镇化进程的加快,江南运河水文情势发生了明显变化。基于运河代表站水位资料、水利分区降雨资料、沿长江(江苏段)主要口门引排水量、出入太湖水量资料,采用Mann-Kendall趋势检验与突变检验法,对代表站水位进行了研究,并初步提出运河水文情势变化的可能原因。结果表明:(1)常州年最高水位及汛期5月、9月平均水位上升可能与湖西区四闸净引水量上升有关;而洛社与无锡(大)汛期5月、9月平均水位上升与武澄锡虞区沿长江(江苏段)口门净引水量显著上升有关,6月、7月、8月平均水位上升可能与地区涝水出路受阻导致原先入太湖的水量改为入运河有关;受张家港、十一圩闸、望虞闸引水及运河上游来水的共同影响,苏州(枫桥)亦出现水位同步上升的趋势。(2)运河代表站水位变异点主要发生在90年代中后期到21世纪初期,与太湖流域各省市陆续进入城镇化快速发展阶段的时间基本一致;同样的降雨,城镇化快速发展后的水位涨幅均明显高于城镇化快速发展前,以无锡(大)最明显。  相似文献   

资源型城市建设用地适宜性评价研究——以济宁市大运河生态经济区为例   总被引：13，自引：1，他引：12  

何丹  金凤君  周璟 《地理研究》2011,30(4):655-666

以山东省济宁市大运河生态经济区为例,探讨了煤炭资源型城市建设用地适宜性评价的指标体系、评价模型以及GIS技术支持下的分析评价方法.选取自然因素、社会经济因素、生态安全因素3方面8个单因子构成该研究区适宜性评价指标体系,利用模糊层次分析法确定指标权重,基于多因素叠加分析和GIS空间分析方法,设计了四种煤炭塌陷的未来情景,...  相似文献   

Physical model study of wave and current conditions at 17th Street Canal breach due to Hurricane Katrina     

W.C. Seabergh 《Ocean Engineering》2010,37(1):48-58

A 1:50 scale physical model was constructed for the 17th Street Canal region, New Orleans, on the southern coast of Lake Pontchartrain, as part of the Interagency Performance Evaluation Task Force (IPET) study of Hurricane Katrina. The purpose of the 1350 m² physical model that represented about 3.4 km² of the local area was to aid in defining wave and water velocity conditions in the 17th Street Canal during the time period leading up to the breaching of the floodwall within the Canal. In the immediate period following this disaster, there were many hypothesis of failure put forth in the media. Some of these hypothesis indicated wave action may have been the underlying cause of the failure of the 17th Street Canal floodwall. Some performed numerical work with inappropriate boundary conditions, which indicated strong wave-generated currents may have caused erosion along the floodwalls. This physical model study indicated a number of wave-attenuating processes occurring as waves approached the location of the breach. Wave height reduction resulted due to: (1) refraction of wave energy over the shallower submerged land areas surrounding the harbor away from the canal; (2) reflection of energy off vertical walls in the region between the entrance to the canal near the Coast Guard Harbor and the bridge; and (3) interaction of the wave with the Hammond Highway bridge, including reflection and transmission loss. Wave heights near the lakeside of the bridge were 0.3-0.9 m in height, reduced from 1.8 to 2.7 m wave heights in the open lake. Waves on the south side of the bridge, near the breach, were further reduced to heights below 0.3 m. These results supported the conclusion that waves were not a significant factor for the 17th Street Canal floodwall failure. Other IPET investigations determined floodwall failure was of a geotechnical nature due to the high surge water level. The physical model also provided calibration information for numerical wave models. The effects of debris on flow and waves after the breach was formed were also investigated.  相似文献   

石岛湾东北侧水道对环境影响的数值模拟   总被引：1，自引：0，他引：1  

张学超  宋喜红  刘缵延 《海洋通报》2007,26(6):61-67

随着经济的发展,石岛湾的环境污染日趋严重。为了改善其海洋生态环境,并增加航运能力,开挖入海通道是非常必要的。通过对石岛湾海水交换率、海水半更新期的估计,以及湾内示踪物浓度分布的数值模拟,研究了开挖多种入海通道的预案,模拟结果显示:石岛湾东北部开挖宽300m或500m水道方案的水体交换效果不及开挖宽800m的方案,后者可明显降低海湾东部的示踪物浓度,有利于湾内的水交换。而开挖的水道宽度增至1000m或1500m后也不会再更加明显地改善石岛湾的水环境,说明可选择开挖宽800m水道的方案。  相似文献   

京杭运河续建工程（山东段）港口建设的几个问题及建议     

沈荣钊 《海岸工程》1999,18(3):87-89

针对目前京驼河续建工程港口建设的实际情况,分析了影响京杭运河续建工程港口建设的主要问题是投资制品大,原设计规模偏大,港口运量设计船型和装卸机械偏大,并提出了修正港口初步设计和由航运部门兴建逐渐转为乡镇兴建的建议。  相似文献   

江河源区水汽输送与收支的时空演变特征分析     

陈亚玲  文军  刘蓉  蒋雨芹  任国强  李悦绮  张强  刘正 《高原气象》2022,(1):167-176

江河源区位于青藏高原腹地,是东亚气候变化的敏感区之一,研究水汽的分布、输送及收支对于理解区域降水特征具有重要意义.本研究基于1980-2019年欧洲中期天气预报中心(ECMWF)的ERA5再分析资料,结合1981-2010年国家气象科学数据中心9个探空站资料,分析了江河源及其毗邻地区水汽分布、输送及各边界水汽收支的时空...  相似文献   

雅鲁藏布大峡谷地区近地面-大气间水热交换特征分析     

张强  文军  武月月  陈亚玲  李悦绮  刘正 《高原气象》2022,(1):153-166

利用欧洲中期天气预报中心第五代再分析数据产品,归类分析了藏东南雅鲁藏布大峡谷地区水汽输送类别.选取大峡谷地区排龙站、墨脱站两个站点2019年涡动相关系统观测数据,分析不同水汽条件下雅鲁藏布大峡谷地区不同位置近地面水热交换通量的日变化特征.结果表明:高原季风期对应大峡谷地区水汽强输送期和温湿期,高原非季风期则相反.墨脱站...  相似文献   

A River Running West: The Life of John Wesley Powell     

《The Professional geographer》2013,65(3):405-407

  相似文献   

《京杭运河遗产保护规划图》图例设计     

万金红  谭徐明 《测绘软科学研究》2012,(2):70-74

在运河“申遗” 工作的推动下,以京杭运河为代表的大量水利工程相继成各级文物保护单位,水利、文物等部门相继开展了古代水利工程保护与管理规划的编制工作、由于古代水利工程保护的特殊性．在保护规划图编绘的过程中发现已有的规划图编绘技术标准不能满足实际工作的需求．突出地表现在现有规划要素图例不能完整地表达保护规划内容,本文根据古代水利工程保护特殊要求．结合当前已有的规划图编绘技术标准和成果,提出了京杭运河保护与管理规划图图例系统和具体设计方案。  相似文献