宁夏一次大风扬沙天气过程机制分析     

谭志强  桑建人  纪晓玲  邵建  朱晓炜 《干旱区地理》2017,40(6):1134-1142

利用宁夏25个常规地面观测站逐时资料和欧洲中期天气预报中心（ECMWF）ERA-Interim逐6 h 0.125º×0.125º分辨率再分析资料,对宁夏2016年5月11日大风扬沙天气过程的天气形势、影响系统及其热力、动力条件和形成机制进行了分析。结果表明：（1）大风和扬沙呈现出时间位相上的不一致性,沙尘超前大风约6 h。（2）200 hPa高空急流、500 hPa锋区、700 hPa低空急流和地面冷锋是此次过程的主要影响系统。（3）大风在不同阶段对扬沙起不同作用,在初期有利于扬沙的传输,后期对扬沙起抑制作用。（4）动量下传和变压风是大风形成和发展的直接原因,感热通量通过加强地面湍流形成混合层,从而引导动量下传是其间接原因,动量下传的重要机制是对流层高层高位涡的下传,过程风力最强时位涡高值区（≥2.0 PVU）由200 hPa下传至520 hPa。（5）扬沙的产生主要是冷平流和感热通量形成的热力不稳定共同作用的结果,变压风和动量下传大风是扬沙的输送机制,次级环流缺失和冷平流中心过低（750 hPa）对沙尘输送高度的抑制作用是沙尘天气偏弱的主要原因。  相似文献   

A wind tunnel investigation of the influences of fetch length on the flux profile of a sand cloud blowing over a gravel surface     

Zhibao Dong  Hongtao Wang  Xiaoping Liu  Xunming Wang 《地球表面变化过程与地形》2004,29(13):1613-1626

Wind tunnel tests were conducted to examine the fetch effect of a gravel surface on the ?ux pro?le of the sand cloud blowing over it using typical dune sand. The results suggest that the ?ux pro?le of blown sand over a gravel surface differs from that over a sandy surface and is characterized by a peak ?ux at a height above the surface while that over a sandy surface decreases exponentially with height. The ?ux pro?le of a sand cloud over a gravel surface can be expressed by a Gaussian peak function: q = a + b exp (?0·5((h ? c)/d)²), where q is the sand transport rate at height h, and a, b, c and d are regression coef?cients. The signi?cance of the coef?cients in the function could be de?ned in accordance with the fetch length of the gravel surface and wind velocity. Coef?cient c represents the peak ?ux height and increases with both wind velocity and fetch length, implying that the peak ?ux height is related to the bounce height of the particles in the blowing sand cloud. Coef?cient d shows a tendency to increase with both wind velocity and fetch length. The sum of a and b, representing the peak ?ux, increases with wind velocity but decreases with fetch length. The average saltation height derived from the cumulative percentage curve shows a tendency to increase with both the fetch length and wind velocity. For any fetch length of a gravel surface the sand transport equation is expressed as Q = C(1 ? U_t/U)(ρ/g)U³, where Q is the sand transport rate, U is the wind velocity, U_t is the threshold velocity measured at the same height as U, g is the gravitational acceleration, ρ is the air density, C is a proportionality coef?cient that decreases with the fetch length of the gravel surface. At a given wind velocity, the sand transport rate over a gravel surface is only 52–68 per cent of that over a sandy surface. The ?ux rate in true creep over a gravel surface increases with wind velocity but decreases with the fetch length, whereas the creep proportion (the ratio of creep ?ux to the sand transport rate) decreases with both the wind velocity and fetch length. Two‐variable (including fetch length and wind velocity) equations were developed to predict the peak ?ux height, average saltation height and transport rate. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

南极中山站吹雪雪暴天气分析   总被引：1，自引：0，他引：1       下载免费PDF全文

许淙  万军  吕非 《极地研究》2004,15(1):39-45

本文利用 2 0 0 3年 1月至 2 0 0 3年 1 2月在中国南极中山站考察期间的天气观测记录和气象传真图 ,对东南极中山站地区的吹雪和雪暴天气进行了统计和天气学分析研究。着重分析了吹雪雪暴天气的时间分布和风场 ,温湿场的特点以及相应的天气形势 ,指出了中山站地区预报吹雪雪暴天气的特点  相似文献   

Wind tunnel experimental study on shed tunnels to prevent and control blowing snow on highways北大核心CSCD     

马磊  刘健  冉武平  胡智轩  李在蓝  俞祥祥 《冰川冻土》2022,44(2):726-734

There is a severe phenomenon of blowing snow by wind in winter in Mayitas area of Xinjiang. Road traffic interruptions and casualties caused by wind and snow disasters often occur. The existing engineering measures can alleviate the problems of low visibility and problems with accumulating snow on pavement caused by wind and snow to a certain extent, but cannot completely eliminate the impact. Aiming at the problem that the blowing snow disaster difficult to be completely cured under strong wind conditions, a shed tunnel engineering treatment scheme is proposed, and a wind tunnel simulation experiment is carried out on the shed tunnel form and snow prevention scheme at the entrance of the tunnel. The wind tunnel experimental section is 8 m long, 1. 3 m horizontally wide and 1 m high. The shed tunnel model is made by 1:60 scale 3D printing method, the snow barrier model is made of wooden strips, and the simulation medium is made of fine sand, refined salt and sawdust. Firstly, three kinds of shed structures, including fully enclosed, overhanging and ventilated, were simulated under the condition of 90° wind direction, and compared with the form of blowing snow stacking. Three parameters for similarity were used:density, particle size and stacking shape. The similarity is determined by weighted Euclidean distance between simulation medium and blowing snow, the similarity of the slump angle of the predecessors is verified, and the most suitable medium for simulating blowing snow is deduced. According to the experimental results, combined with the actual situation of wind blowing and snow disasters in Mayitas, flow field of the closed shed tunnel by a wind direction angle of 30° has been separately conducted with or without protective measures. The results show that when the wind tunnel stacking experiment is used to study the deposition state of blowing snow under non-low temperature conditions, the sawdust has good similarity with the blowing snow in the process of wind and snow movement. A large amount of medium was poured into the ventilated shed during the experiment, which proved that its anti-wind and snow performance was not ideal. By contrast, the closed shed and the overhanging shed have better wind and snow prevention effects. The snow barrier has a good blowing snow inhibition function at the entrance. From the stacking experiment, in the comparison with and without snow barrier, volume of the medium in the shed is very different, which proves that the snow barrier can effectively prevent the blowing snow from entering the shed. Among them, the difference in wind speed inside and outside the shed is obvious, which proves that snow barrier can significantly reduce the wind speed outside the shed and has the function of inhibiting the formation of weak wind areas inside the shed. The study has confirmed that the shed tunnel project with suitable snow barrier layout plan for tunnel entrance protection is an effective means to control wind and snow disasters. For highway traffic in Xinjiang, it is a feasible solution to use shed tunnel engineering to control blowing snow disasters. After dealing with the snow deposition at the entrance of shed tunnel, the shed tunnel engineering form of low-cost environment integration and the vehicle operation safety guarantee measures of long-distance shed tunnel are the problems that need to be solved in the future. © 2022 Tianjin Press of Chinese Herbal Medicines. All rights reserved.  相似文献   

上海市苏州河段水质污染综合治理研究     

唐礼智  汤建中 《地理与地理信息科学》2001,17(4):81-84,94

该文针对苏州河水质污染的特定状况 ,提出在全面规划、远近结合、突出重点、分步实施的原则指导下 ,应积极推行支流截污、引清调水、底泥处理、曝气复氧、沿岸绿化 5大工程 ,以达到彻底整治苏州河水质污染的目标。  相似文献   

神府矿区突水溃砂地质灾害研究   总被引：2，自引：0，他引：2  

魏秉亮 《中国煤田地质》1996,(2)

针对神府矿区威肋安全生产的最大地质灾害──突水溃砂，本文通过实例，结合勘察成果，对其地质背景形成机理进行了总结分析，认为解决这一地质灾害目前最有效的措施是采前疏排基岩顶部直接充水含水层中地下水，使砂失去地下水载体而无法进入矿井。  相似文献   

宁夏河东沙地不同植被覆盖度的土壤起沙特征试验研究   总被引：9，自引：5，他引：4  

刘静  毛军需  王连喜  石学军  何连 《中国沙漠》2007,27(3):436-441

为了评价宁夏河东沙地不同生态破坏与植被恢复措施的防沙治沙效果,利用自行设计的5个高度降尘接沙仪和4台内蒙古农牧大学生产的水平输沙接沙仪,通过人工吹风的方式,于2004年5月20—23日在不同植被覆盖度的下垫面上,开展不同垂直高度和不同距离的降尘试验和不同垂直高度的沙尘粒子截留试验。植被类型为自然裸露沙丘、低覆盖度天然草场、围栏禁牧的自然恢复草场、人工草方格沙丘治理结合飞播的生态恢复治理草地及原退耕还牧的复垦农田。结果表明,裸露沙丘土壤风蚀最严重,防沙治沙以围栏禁牧效果最好,其次为草网格治理,复垦农田和流动沙丘均容易起沙。  相似文献   

积雪水文模拟中的关键问题及其研究进展   总被引：3，自引：1，他引：2  

李弘毅  王建 《冰川冻土》2013,35(2):430-437

针对近年来积雪水文模拟研究的发展趋势, 在简要评述积雪模拟基本方法的基础上, 分别就各类方法的不同着眼点展开讨论, 从模拟方案的简繁、 积雪面积等重要状态变量在模型中如何体现等角度进行了叙述.针对我国青藏高原积雪特征, 提炼出现阶段空间分布式积雪水文模拟中的3个关键问题: 网格尺度积雪空间异质性的模拟、 风吹雪的空间参数化、 季节性冻土下垫面的融雪模拟. 分别就这些问题, 回溯了国内外最新研究进展, 强调了发展积雪衰减曲线在网格尺度积雪模拟中的重要性, 讨论了山区环境中具有操作性的风吹雪空间参数化方案, 分析了冻土下垫面融雪研究存在的一些具体问题.  相似文献   

狮泉河盆地第二期风沙灾害整治研究   总被引：8，自引：2，他引：6  

张春来  邹学勇  靳鹤龄  郭迎胜 《中国沙漠》2001,21(2):157-163

根据狮泉河盆地自然、社会经济条件和风沙灾害特点,制定了由机械措施、生物措施和辅助措施组成的综合整治方案。工程体系在风沙运动原理和可持续发展思想的指导下,不仅可以行之有效地控制风沙灾害,改善盆地生态环境,而且提出以开发土地资源和水资源为主旨的新的经济增长点,体现了高寒干旱地区融风沙灾害整治与资源开发于一体的新思路。  相似文献   

Application of a distributed blowing snow model to the Arctic     

J. W. POMEROY  P. MARSH  D. M. GRAY 《水文研究》1997,11(11):1451-1464

Transportation, sublimation and accumulation of snow dominate snow cover development in the Arctic and produce episodic high evaporative fluxes. Unfortunately, blowing snow processes are not presently incorporated in any hydrological or meteorological models. To demonstrate the application of simple algorithms that represent blowing snow processes, monthly snow accumulation, relocation and sublimation fluxes were calculated and applied in a spatially distributed manner to a 68-km² catchment in the low Arctic of north-western Canada. The model uses a Landsat-derived vegetation classification and a digital elevation model to segregate the basin into snow ‘sources’ and ‘sinks’. The model then relocates snow from sources to sinks and calculates in-transit sublimation loss. The resulting annual snow accumulation in specific landscape types was compared with the result of intensive surveys of snow depth and density. On an annual basis, 28% of annual snowfall sublimated from tundra surfaces whilst 18% was transported to sink areas. Annual blowing snow transport to sink areas amounted to an additional 16% of annual snowfall to shrub–tundra and an additional 182% to drifts. For the catchment, 19·5% of annual snowfall sublimated from blowing snow, 5·8% was transported into the catchment and 86·5% accumulated on the ground. The model overestimated snow accumulation in the catchment by 6%. The application demonstrates that winter precipitation alone is insufficient to calculate snow accumulation and that blowing snow processes and landscape patterns govern the spatial distribution and total accumulation of snow water equivalent over the winter. These processes can be modelled by relatively simple algorithms, and, when distributed by landscape type over the catchment, produce reasonable estimates of snow accumulation and loss in wind-swept regions. © 1997 John Wiley & Sons, Ltd.  相似文献