国家气象中心新一代业务中期预报模式T213L31的主要特点   总被引：12，自引：3，他引：12  

陈起英  姚明明  王雨 《气象》2004,30(10):16-21

T2 1 3中期数值预报系统于 2 0 0 2年 9月 1日起在国家气象中心正式业务化。作为此系统核心的T2 1 3L31全球模式与原业务模式T1 0 6L1 9相比 ,采用了一些新的数值技术 ,包括半拉格朗日时间积分方案的引入 ,采用规约格点 ,分布内存与共享内存并行相结合 ,从而在目前有限的计算机资源条件下 ,能积分高分辨率的模式。更重要的是 ,模式采用了一些更新、具有更真实物理概念的物理过程参数化方案 ,对于辐射方案、次网格尺度地形参数化、积云对流方案、云方案、陆面过程方案都作了很大改进 ,从而克服了许多T1 0 6L1 9模式中存在的问题 ,明显提高了T2 1 3L31模式的预报技巧。  相似文献   

舟山港台风风暴潮的分析及预报          下载免费PDF全文

项素清 《气象》2004,30(3):35-38

利用 1 956～ 2 0 0 0年舟山市定海验潮站潮位观测资料 ,对历年影响舟山的台风风暴潮灾进行了全面的统计分析。将台风按路径分型 ,分析了不同路径台风风暴潮的特点 ,并用基于PRESS准则的逐步回归方法 ,建立了不同路径风暴潮的预报模型。  相似文献   

基于GIS/RS的流域水文过程分布式模拟——Ⅰ模型的原理与结构   总被引：5，自引：6，他引：5       下载免费PDF全文

王中根  郑红星  刘昌明  赵为民 《水科学进展》2004,15(4):501-505

面向流域水资源管理,提出了一个基于GIS/RS的流域分布式水文模型,模型主要包括单元水文模型与河网汇流模型两大部分。单元水文模型涉及到冠层截留、融雪、蒸散发、坡面流、非饱和土壤水运动和地下水出流等水文物理过程。产流计算考虑到地形坡度的影响采用基于地形指数的计算方法。汇流演算基于河网结构采用分段马斯京根方法。模型的大部分参数与输入信息可以利用GIS和RS技术获取,能够对气候变化和人类活动对下垫面的改变,做出快速的模拟与响应。  相似文献   

Hydro-thermal performance of multilayer capillary barriers in arid lands     

A. M. O. Mohamed  I. Shooshpasha 《Geotechnical and Geological Engineering》2004,22(1):19-42

In this study, a capillary barrier system was designed and tested for an arid land environment. To simulate arid land conditions of high temperature and sub-irrigation systems, the barrier was subjected to thermal and hydraulic gradients in opposite directions; to test the barrier system under these severe conditions, an experimental apparatus was designed and fabricated. The multilayer capillary barrier consisted of three layers made of silica sand, a mixture of sand and bentonite in equal portions, and a mixture of clay (25%) and aggregate (75%). Several one dimensional coupled heat and moisture tests were performed. Temperature variations along the thickness of the barrier were recorded as a function of time, and at the end of each test, the barrier was sliced into small sections, for the determination of volumetric water content as a function of distance from the heat source. The experimental results were discussed in view of the barrier's intended purpose of its ability to store moisture for long time durations. Coupled heat and moisture flow equations were developed and solved numerically via a finite difference method. Diffusivity parameters were calculated by using experimental results, a numerical model, and Powell's conjugate directions method of nonlinear optimization. The model was calibrated and the results were discussed. Good agreement between calculated and experimental results was obtained. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Simulations of a coupled hydro-chemo-mechanical system in rocks     

Jishan Liu  Barry H. Brady 《Geotechnical and Geological Engineering》2004,22(1):121-133

A coupled hydro-chemo-mechanical numerical model is developed for these coupled phenomena in many engineering fields. The model has been applied to predicting the response of a stressed rockmass column to an injected reactive fluid (reagent) flow. The response includes evolutions of porosity, permeability, reagent and mineral concentrations during dissolution. In the model, the progress of dissolution is defined by the change in porosity ratio and the porosity increases with dissolution assuming there is no precipitation. The numerical evolutions of porosity, permeability, reagent and mineral concentrations during dissolution are validated against steady state solutions. The model results show that these evolutions are regulated to a certain extent by the applied external loadings: an applied extensional stress enhances the progress of the dissolution process while an applied compression stress slows the progress of the dissolution process. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

中国西部干旱区生态环境演变过程   总被引：10，自引：13，他引：10  

潘晓玲  马映军  高炜  齐家国  师庆东  陆海燕 《中国沙漠》2004,24(6):663-673

根据湖沼沉积、黄土沉积和冰积等地质记录，运用地理信息系统、遥感、生态景观学等方法．从万年、千年和百年及百年以下四个时间尺度对中国西部干旱区生态环境演变过程进行研究。结果表明，全新世以来，中国西部干旱区的气候变化经历了多次的相对暖干和相对冷湿交替变化，变化历程较为复杂。早全新世、中全新世、晚全新世气候特点因地因时而异，但总体特征以干旱化为主，280～350a来，降水量有明显的减少趋势，并表现出显著的周期性。但在近半个世纪以来，中国天山地区的气候变化特征表现为气温升高，降水量增加。总的来说，从20世纪80年代以来，新疆的气候趋于好转，植被覆盖状况改善明显，山地森林、草甸、人工绿洲的面积均呈增加趋势。研究结果还表明，在一定尺度的气候背景条件下，地表的植被覆盖对调节绿洲区域气候有着积极的作用，可增加局部地区的降水。  相似文献   

Relationship between solar radiation and the development and morphology of small cirque glaciers (Maladeta Mountain massif, Central Pyrenees, Spain)     

Javier Chueca  Asunción Julián 《Geografiska Annaler: Series A, Physical Geography》2004,86(1):81-89

Abstract Spatial and temporal variations in radiative fluxes influence glacier mass‐balance in mountain areas. The primary goal of this study was to assess differences in solar radiation on three glacial cirques located in the Maladeta Mountain massif (Central Spanish Pyrenees), and analyse their implications on glacier development and morphology. A quantitative approach is adopted to obtain the values of solar radiation (direct, diffuse and global radiation), combining several field data parameters (measured at 55 control‐points) with the solar radiation modelling package Ecosim. The data obtained confirm that the morphologies of the glacial bodies developed in the three cirques have a good correlation with the spatial variation on solar radiation inputs, favouring also the conservation (Aneto and Coronas cirques) or total vanishing (Llosás cirque) of the glacial remnants analysed here. The study shows how strongly in this Alpine‐Mediterranean context solar radiation — firstly as a function of latitude and time of year, and locally as a function of topographic slope, aspect and shadowing — controls the mass‐balance and the spatial distribution of melting in small glaciers, having an effect on the development of their morphologies.  相似文献   

Further examples of ventifacts and unusual patterned ground from the Falkland Islands, South Atlantic     

Peter Wilson  Emma J. Edwards 《Geografiska Annaler: Series A, Physical Geography》2004,86(1):107-115

Abstract Examples of ventifacts and forms of unusual patterned ground that differ in situation, characteristics and/or origin to types reported previously are described from the Falkland Islands, South Atlantic. The ventifacts, represented by clasts projecting from an eroding tillite shore platform, have been grooved by the passage of windblown sand. The patterned ground forms comprise stone polygons on clay loam regolith, stone polygons on peat, peat‐filled desiccation cracks on peat, and clusters of on‐edge clasts (stone packings) on a gravel beach. Aeolian transport of particles is considered responsible for the infill of the polygonal cracks. The clusters of on‐edge clasts are thought to have developed as a result of wave action, in particular backwash and/or undertow. Although these features occupy small surface areas they provide useful information about local geomorphic processes and testify to the marked diversity of such features in nature.  相似文献   

Postglacial topographic evolution of glaciated valleys: a stochastic landscape evolution model   总被引：1，自引：0，他引：1  

Simon J. Dadson  Michael Church 《地球表面变化过程与地形》2005,30(11):1387-1403

The retreat of valley glaciers has a dramatic effect on the stability of glaciated valleys and exerts a prolonged influence on the subsequent fluvial sediment transport regime. We have studied the evolution of an idealized glaciated valley during the period following retreat of ice using a numerical model. The model incorporates a stochastic process to represent deep‐seated landsliding, non‐linear diffusion to represent shallow landsliding and an approximation of the Bagnold relation to represent fluvial sediment transport. It was calibrated using field data from several recent surveys within British Columbia, Canada. We present ensemble model results and compare them with results from a deterministic linear‐diffusion model to show that explicit representation of large landslides is necessary to reproduce the morphology and channel network structure of a typical postglacial valley. Our model predicts a rapid rate of fluvial sediment transport following deglaciation with a subsequent gradual decline, similar to that inferred for Holocene time. We also describe how changes in the model parameters affect the estimated magnitude and duration of the paraglacial sediment pulse. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Numerical simulation for 1975 Haicheng and 1999 Xiuyan earthquake processes by DDA+FEM     

张瑞青  魏富胜  乔成斌  林邦慧 《地震学报(英文版)》2005,18(2):171-179

Introduction The Xiuyan earthquake(MS=5.4)on Nov.29,1999,occurred between Hushan town and Pi-anling town at the southeast end of the aftershocks of Haicheng earthquake(MS=7.3).These two earthquakes′sequences are highly similar in the way that the foreshocks are very frequent,focal mechanisms of the main shocks are about the same and fault strikes are approximately in the same direction.It is important to study these earthquakes for further research on seismogenesis to fore-cast earthquake…  相似文献