2009年4月北方一次强沙尘暴过程的特征分析和数值模拟

利用观测资料对2009年春季4月22-24日强沙尘暴过程的近地面气象要素(气温、气压、风速)变化和PM10进行分析.结果表明:蒙古气旋和冷锋是这次强沙尘暴的主要影响系统;沙尘暴过程前后温、压和风速有剧烈变化;PM10的强度能较好地反映沙尘暴强度.在观测资料分析基础上,利用沙尘暴数值预报系统对此次过程进行了模拟,采用模拟结果对地面沙尘浓度和起沙进行了分析.结果表明:模式能较好地模拟出这次沙尘天气的时间和空间演变特征,模拟沙尘浓度大值区与强沙尘暴的范围较为一致,比较白天早间和下午的沙尘浓度分布,发现其具有日变化;这次大范围的沙尘天气的起沙中心分别是南疆塔里木盆地、甘肃、内蒙古的西部及蒙古国南部,垂直沙通量超过50 mg·m2·s-1;沙尘浓度垂直输送的高度在550hPa以下,起沙后的沙尘粒子主要靠对流层低层的大风长距离地输送;对不同地区起沙过程贡献最大的沙尘粒子的粒径不尽相同,但是对起沙量贡献最大的是粒径在2μm相似文献   

The integrated impacts of natural processes and human activities on groundwater salinization in the coastal aquifers of Beihai,southern China

Salinization in coastal aquifers is usually related to both seawater intrusion and water–rock interaction. The results of chemical and isotopic methods were combined to identify the origin and processes of groundwater salinization in Daguansha area of Beihai, southern China. The concentrations of the major ions that dominate in seawater (Cl^?, Na⁺, Ca²⁺, Mg²⁺ and SO ₄ ^2– ), as well as the isotopic content and ratios (²H, ¹⁸O, ⁸⁷Sr/⁸⁶Sr and ¹³C), suggest that the salinization occurring in the aquifer of the coastal plain is related to seawater and that the prevailing hydrochemical processes are evaporation, mixing, dissolution and ion exchange. For the unconfined aquifer, groundwater salinization has occurred in an area that is significantly influenced by land-based sea farming. The integrated impacts of seawater intrusion from the Beibuwan Gulf and infiltration of seawater from the culture ponds are identified in the shallowest confined aquifer (I) in the middle of the area (site BBW2). Leakage from this polluted confined aquifer causes the salinization of groundwater in the underlying confined aquifer (II). At the coastal monitoring site (BBW3), confined aquifer I and lower confined aquifer II are heavily contaminated by seawater intrusion. The weak connectivity between the upper aquifers, and the seaward movement of freshwater, prevents saltwater from encroaching the deepest confined aquifer (III). A conceptual model is presented. Above all, understanding of the origin and processes of groundwater salinization will provide essential information for the planning and sustainable management of groundwater resources in this region.     

乡镇“有为政府”产业政策的逻辑与检验——基于新结构经济学视角

为解决乡村振兴中乡镇政府如何选择正确产业和如何制定合理产业政策2个重要问题,运用新结构经济学“增长甄别与因势利导框架”分析并提出乡镇“有为政府”产业政策演化的逻辑框架：1）选择产业,依据“两步六轨法”选择具备相似资源禀赋、约束条件的产业。2）政策制定,针对筛选出的产业制定合理的政策内容、选择适当的政策工具,以支持产业发展。以该逻辑框架为依据分析了云南省西双版纳州勐罕镇的产业现状、目标乡镇比较优势产业,发现勐罕镇领先型产业为菠萝种植业,应通过引进菠萝深度加工企业,建设营销网络、运输网络,提供市场信息支持产业发展;转进型产业为传统种植业和特色养殖业,应通过建立冷链物流等基础设施、培训农户种养能力,提高农户市场参与度;“弯道超车型”产业为酒类制造和傣药生产等,应通过联合农户开发制造技术体系,协助注册品牌商标,建设生产和成品制造基地等促进产业发展,从而完成了逻辑框架的实践检验。总体上,因势利导逻辑框架既结合实际又着眼未来,为乡镇政府的产业政策决策提供了理论指导和经验借鉴。     

Agent-based modeling within a cyberinfrastructure environment: a service-oriented computing approach

Agent-based models (ABM) allow for the bottom-up simulation of dynamics in complex adaptive spatial systems through the explicit representation of pattern–process interactions. This bottom-up simulation, however, has been identified as both data- and computing-intensive. While cyberinfrastrucutre provides such support for intensive computation, the appropriate management and use of cyberinfrastructure (CI)-enabled computing resources for ABM raise a challenging and intriguing issue. To gain insight into this issue, in this article we present a service-oriented simulation framework that supports spatially explicit agent-based modeling within a CI environment. This framework is designed at three levels: intermodel, intrasimulation, and individual. Functionalities at these levels are encapsulated into services, each of which is an assembly of new or existing services. Services at the intermodel and intrasimulation levels are suitable for generic ABM; individual-level services are designed specifically for modeling intelligent agents. The service-oriented simulation framework enables the integration of domain-specific functionalities for ABM and allows access to high-performance and distributed computing resources to perform simulation tasks that are often computationally intensive. We used a case study to investigate the utility of the framework in enabling agent-based modeling within a CI environment. We conducted experiments using supercomputing resources on the TeraGrid – a key element of the US CI. It is indicated that the service-oriented framework facilitates the leverage of CI-enabled resources for computationally intensive agent-based modeling.     

GPS/BDS组合单点定位算法及结果分析

介绍了GPS、北斗卫星导航系统的时间和坐标系统,并对二者之间的转换和统一进行了概括分析,推导了GPS/BDS组合单点定位的函数模型和随机模型。编制了相应的计算程序,对实测数据进行了处理与分析。结果表明:相对于单系统,GPS/BDS组合系统能够增加可观测卫星数、减小DOP值、提高定位的精度和可靠性,同时也说明算法可行,程序可靠。     

2007年3月3—5日辽宁省暴雪和大风天气的中尺度分析

使用中尺度数值模式WRFV2.2.1对辽宁省2007年3月3-5日的暴雪和大风天气过程进行了数值模拟,结合10min一次的地面自动观测站资料和数字化多普勒天气雷达探测资料,研究了中尺度重力波的结构及其环境场特征,探讨了波动的激发机制.对流层上层中尺度重力波生成在350-250 hPa(约9-11 km),周期为2-3h,水平波长30-40 km,波动沿水平方向传播约9h.地面气压扰动振幅约为2 hPa,周期为2-3 h,波动由西南向东北方向传播,方向与地面风向相反.沿波的传播方向,地面观测的逐时降水量呈波动特征,周期约为2h.对流层上层中尺度重力波减弱后,雷达降水回波强度出现显著的波动特征.对流层上层中尺度重力波生成在朝向脊区传播的高空急流出口区下方,300 hPa环境场具有显著的切变不稳定特征.波动生成在理查逊数小于0.25的地区,在中尺度重力波生成的高度上,暖平流强,风速低,风切变大.中尺度重力波生成地区出现显著的不平衡气流,拉格朗日罗斯贝数大于0.7,水平散度倾向出现明显的大值,其中-▽w·(e)v/(e)v的量级明显大于其他各项,表明对流层上层重力波的生成及发展与环境场的显著风切变有关.     

Study on Moist Potential Vorticity and Symmetric Instabilityduring a Heavy Rain Event Occurred inthe Jiang-Huai Valleys

1.IntroductionSubsequenttothe1970s,manynativemeteorologicalresearchersdiscoveredthatmesoaiscalesymmetricinstabilitydisturbanceislikelytoplayanimportantroleintriggeringandorganizingbandedconvectionandresponsibledirectlyformultiplerain--bands.Asahighly...     

复杂地形下山谷风的数值模拟

利用中尺度数值模式MM5,选用NCEP全球客观分析资料(1°×1°)和国内高空地面资料为初始场,采用张驰逼近边界条件和单一冰相水汽方案,模拟了河南省西部山区的复杂地形对2006年6月19日局地环流的影响,结果表明:太行山的南麓和熊耳山的东侧都有因地形热力作用而形成的山谷风存在。     

闽东一次暴雨过程的数值模拟和诊断分析

用中尺度数值模式MM5对发生在闽东的一次暴雨天气过程进行了数值模拟,并利用模式输出的较高时空分辨率的结果对有关物理量进行诊断分析。结果表明:中尺度低涡是本次暴雨过程的主要影响系统之一,低涡的时空演变特征与暴雨中心的移动和雨强的变化相一致。对风场的试验结果表明:高低空急流不仅为暴雨的形成提供了充沛的水汽条件,而且也是暴雨产生的一种重要的触发机制。     

双热带气旋相互作用的研究

采用无基本气流的无辐散正压模式模拟了双热带气旋的运动。应用非对称理论研究了双热带气旋的相互作用。双热带气旋中的每个热带气旋主要由通过其中心的非对称气流（即通风气流）作用而移动。这股非对称气流是由其自身的线性和非线性效应产生的非对称涡旋与其配对热带气旋形成的非对称涡旋相叠加而引起的。