地形、冷池出流和暖湿空气相互作用造成北京一次局地强降水的观测分析   总被引：1，自引：0，他引：1       下载免费PDF全文

章翠红  夏茹娣  王咏青 《大气科学学报》2018,41(2):207-219

利用地面和探空常规探测资料、多普勒天气雷达以及风廓线雷达资料,对2015年8月7日发生于北京的一次伴随有闪电和冰雹的突发性局地强降水过程的成因进行了分析。结果表明:这次过程发生在强层结不稳定环境中,对流层中层低槽配合低层切变线,促进河北西北部对流发展,并向东南方向移动,形成北京西北部短时强降水;北京中部地区强降水的直接制造者则是新生的局地性雷暴单体,由雷暴冷池出流和暖湿空气在边界层交绥和辐合所触发。北京西北部地形促使冷池出流下山速度加快、冷池出流高度抬高,以及偏东暖湿气流的辐合抬升作用,则是局地雷暴新生的重要影响因子。  相似文献   

河北中部一次具有后向传播特征的副高外围暖区暴雨过程分析     

金晓青  李江波  于雷  闫雪瑾  于爱兵  申莉莉 《沙漠与绿洲气象(新疆气象)》2018,12(4):7-14

利用常规观测、雷达、卫星、加密自动站资料、VDRAS系统(雷达变分分析系统)产品以及ERA-Interim再分析资料,对2013年8月11日发生在河北中部暖区中、伴有强降水和大风、具有后向传播特征的深厚湿对流过程进行分析。结果表明:这是一次发生在副高动力边界的外侧,水汽、热力及对流不稳定边界的内侧附近的过程,该区域有利的对流不稳定条件和触发抬升条件,容易产生对流天气。石家庄东部的对流雨带具有明显的后向传播特征,其发生机制为:受低空切变线和地面辐合线触发,廊坊—保定东部一线(辐合线的北侧)首先出现了雷阵雨,形成雷暴高压,在雷暴群后部(西南方)不断激发出新生雷暴,即有后向传播出现,新生雷暴并入雷暴群后,随引导气流向东北方向移动,造成列车效应,在暖区产生较强降水。  相似文献   

“5.7”广州局地突发特大暴雨中尺度特征及成因分析   总被引：7，自引：0，他引：7  

徐珺  毕宝贵  谌芸  陈涛  宫宇  李嘉睿 《气象学报》2018,76(4):511-524

2017年5月7日广州局地突发特大暴雨,降水集中爆发于广州北部复杂地形区,单点小时雨量大、强降雨持续时间长。然而降水发生于副热带高压边缘、无明显的低空急流等天气系统配合,为弱强迫背景下的华南前汛期暴雨,加之珠三角地形复杂,其触发和组织维持机制等问题引起了气象科研和预报工作者的广泛关注。针对其降水特点,采用5 min自动气象站观测、分钟雨量、风廓线雷达、葵花8号气象卫星红外等高时空分辨率观测数据探讨中尺度对流系统的触发和组织维持过程,发现:中纬度入海高压南侧偏东风和低层切变系统为珠三角边界层南风风速辐合提供了有利的天气背景,喇叭口地形增强了风速辐合。小尺度地形辐射降温配合城市热岛在山前形成高温度梯度区,山风与南风对峙使地面辐合线在山前移速变慢有助于热带云团的生成。地形阻挡抬升和高温度梯度加强上升运动,南风风速脉动使云团迅速向山前移动,最终对流爆发。以暖云降水为主的对流系统产生弱冷池驱动对流系统连续传播,使强降水回波面积增大并在小尺度地形影响下稳定位于增城附近,产生极端小时雨强;中尺度对流系统的单体移动方向和传播方向近乎相反导致系统移动非常缓慢,后向传播明显,最终导致长时间强降水。   相似文献   

基于交通基础地理信息的网络发布研究与实现     

刘峰  刘海青  靳奉祥  张继贤 《测绘科学》2007,32(2):97-99

近年来随着WebGIS技术的日趋成熟,采用WebGIS技术管理空间数据并进行网络发布,供用户快速查询与使用,实现空间信息的网络共享,为空间数据的充分利用和可视化表达提供了一种有效的解决方案。本文以北京市交通地理信息系统开发为例,探讨了交通基础地理信息的网络发布平台构架设计与实现过程,并针对系统关键技术的原理及实现进行了详细阐述,构建了以J2EE为核心,基于ArcIMS的空间信息服务框架体系,是WebGIS技术在交通领域的集成应用。  相似文献   

Fair and equitable sharing of benefits from the utilization of marine genetic resources in areas beyond national jurisdiction: Bridging the gaps between science and policy     

《Marine Policy》2014

Marine genetic resources are a subject of a growing body of research and development activities, as demonstrated by the abundance of marine patented genes reported in GenBank. Given the lack of a comprehensive legal regime for the management of marine genetic resources in areas beyond national jurisdiction, the General Assembly of the United Nations met in 2006 to discuss whether there are regulatory or governance gaps and how to address them. Besides the crystallization of the different political positions, the process is now advancing towards making a decision about whether to develop an international instrument under the United Nations Convention on the Law of the Sea (UNCLOS) for the conservation and sustainable use of marine biological diversity, within which the regulation of access to genetic resources and the sharing of benefits from their utilization has emerged as an in-dissociable issue. In order to propose concrete options to be considered for the establishment of a legal framework addressing these issues, policy-makers need to better understand the feasibility, the costs and the modalities of scientific activities undertaken, together with the actual level of commercialization of new products. They also need to be aware of the already advanced practices in place within the scientific community, especially regarding sharing of non-monetary benefits. This paper particularly highlights and discusses practical scenarios to advance in the international process, based on the approaches adopted in other regional and international regimes for the management of genetic resources and on the best practices developed within the scientific community.  相似文献   

水汽含量对飑线组织结构和强度影响的数值试验   总被引：8，自引：4，他引：4  

孙建华  郑淋淋  赵思雄 《大气科学》2014,38(4):742-755

利用2009年6月3～4日一次产生大风、冰雹强对流天气的飑线个例进行数值试验,研究整层水汽含量及其垂直分布对中尺度对流系统的发生发展过程、组织类型和强度等的影响。本文的试验表明环境场中不同的水汽含量和垂直分布,会影响下沉气流和冷池的强度,从而影响对流的组织形态、维持时间和强度。整层水汽试验表明,增加（减少）水汽,对流增强（减弱）,冷池和雷暴高压增强（减弱）导致大风增强（减弱）。增加水汽越多发展阶段冷池强度越强,最大风速越强,但成熟阶段后期冷池减弱的越快,层状云区的后部入流减弱,不利于雷暴大风的出现和维持。不同层次水汽试验表明,在保持整层水汽含量不变的情况下,线状对流和雷暴大风易发生在中层干、下层湿的环境中,这种层结条件对雷暴高压的增强有重要作用,但不利于整个对流系统的长时间维持。  相似文献   

2014年3月广东一次飑线过程观测及数值模拟分析   总被引：3，自引：0，他引：3  

缪子青  ;何宏让  ;白仕刚  ;汤鹏宇 《气象与减灾研究》2014,(4):7-17

对2014年3月31日广东省一次飑线过程进行了观测资料分析和数值模拟研究。观测资料分析表明:飑线发生在强低空垂直风切变和"上干下湿"的水汽垂直分布的环境条件下。在强盛阶段,飑线上的对流单体多表现为强降水超级单体,有明显的有界弱回波区(BWER)和回波悬垂结构。飑线前沿有明显阵风锋,后侧有弱回波通道,弱回波通道和后侧入流急流(RIJ)相对应,RIJ维持时间较长,对"弓"形回波的形成、地面大风、飑线的维持和快速移动具有重要的作用。模式输出的高分辨率资料分析表明:在减弱阶段飑线移入残留的冷池中,冷池得到加强,此时西南暖湿气流加强,飑线二次发展。成熟飑线的三维结构表现为低层为2支入流、高层为2支出流,且前侧出流速度较快,使得气流倾斜上升,容易形成悬挂回波和弱回波区(WER)。后侧入流下部(600 h Pa高度层以下)的辐散下沉气流是地面大风形成的原因。对流两侧的"涡旋串"(Vortex bunch)对冷暖空气加速入流、对流发展强度和高度以及对流的长时间维持有很大的作用。  相似文献   

云GIS应用于数字城市设计与实现     

石永阁  边馥苓 《地理信息世界》2014,(5)

针对数字城市地理空间框架建设中存在的问题,本文研究和设计实现云环境下GIS应用,构建云GIS实验环境,和传统GIS环境实验结果对比,得出结论:云GIS在基础设施框架、提高硬件资源利用率以及提供高性能的服务方面具有诸多优势,能解决现在数字城市项目建设中存在的问题,值得研究和应用推广。  相似文献   

Influence of rock‐pool characteristics on the distribution and abundance of inter‐tidal fishes          下载免费PDF全文

Gemma E. White  Grant C. Hose  Culum Brown 《Marine Ecology》2015,36(4):1332-1344

Rock pools can be found in inter‐tidal marine environments worldwide; however, there have been few studies exploring what drives their, fish species composition, especially in Australia. The rock‐pool environment is highly dynamic and offers a unique natural laboratory to study the habitat choices, physiological limitations and adaptations of inter‐tidal fish species. In this study rock pools of the Sydney region were sampled to determine how the physical (volume, depth, rock cover and vertical position) and biological (algal cover and predator presence) parameters of pools influence fish distribution and abundance. A total of 27 fish species representing 14 families was observed in tide pools at the four study locations. The five most abundant species were Bathygobius cocosensis, Centropogon australis, Enneapterygius atrogulare, Lepidoblennius haplodactylus and Microcanthus strigatus, which together represented 71% of the total number of fish recorded. Larger rock pools containing more algal and rock ledge cover hosted a larger and more diverse population of fish. Furthermore, certain species were only found in pools with specific characteristics, such as the presence of loose shells, a variety algae or rock cover, suggesting a high degree of habitat specificity. By contrast, some species were ubiquitous and thus can likely tolerate a wide variety of physical conditions.  相似文献   

Vessel buybacks in fisheries: The role of auction and financing structures     

《Marine Policy》2015

Vessel buyback programs intended to address overcapacity and excess capitalization in fisheries can lead to dramatically different levels of decapitalization depending on program structure and availability of vessel-specific information. This paper develops a simple theoretical model of self-financing vessel buybacks to examine equilibrium outcomes using sequential versus take-it-or-leave-it auctions, and financing schemes which allocate costs either homogeneously or according to rents captured through the buyback. This model demonstrates that programs which spread costs evenly among remaining vessels limit the possible extent of buybacks, as do programs which buy vessels one at a time in sequence rather than all at once. In addition to the theoretical modeling, a stylized case study inspired by the Inter-American Tropical Tuna Fishery is also provided. This analysis suggests that a wide range of auction structures could roughly half the size of the existing fleet, and starkly demonstrates how information poor settings can entirely derail a buyback.  相似文献