基于Matlab的Durov三线图的实现   总被引：2，自引：0，他引：2       下载免费PDF全文

任孝宗  刘敏  张迎珍  贺志明  朱秉启 《干旱区地理》2018,41(4):744-750

水化学分类是实现水资源可持续开发利用的重要前提之一。Durov三线图作为主要的水化学分类图因绘制复杂而限制了其在现实中的应用,且一些常见的水化学软件也不具备绘制Durov三线图的功能。Durov三线图包括原始型Durov三线图及在其基础上演变而成的扩展型Durov三线图。通过介绍两种Durov三线图的差异、组成特征和投影原理,提出了在Durov三线图中建立坐标系的方法,并推导了将水化学数据投影到Durov三线图的公式。在此基础上,阐述了基于Matlab语言编程实现原始型Durov三线图和扩展型Durov三线图的方法和流程,并以公开发表的数据绘制了两种Durov三线图。基于相同的数据比较发现,相关水化学软件绘制的原始型Durov三线图及一些公开发表的研究成果中的扩展型Durov三线图与本文所用Matlab语言绘制的Durov三线图相一致,表明该程序准确可行。本程序既可以实现原始型Durov三线图的绘制,也可以实现常见水化学软件不能完成的扩展型Durov三线图的绘制。该程序的应用,将有助于Durov三线图的高效应用,特别是扩展型Durov三线图的应用不但可以作为水化学分类的依据,同时还可以指示某些水化学过程。  相似文献   

生态保护红线成效评估框架与指标方法   总被引：1，自引：0，他引：1  

侯鹏  王桥  杨旻  李静  翟俊  蔡明勇 《地理研究》2018,37(10):1927-1937

生态保护红线是在自然保护区、重点生态功能区、风景名胜区、森林公园等诸多区域生态管理制度不断实践基础上,面对中国国土开发和生态保护的复杂关系,继承和创新提出的一种新型区域生态管控制度,已经成为推动国家生态文明建设的重大战略。如何科学评估生态保护红线保护成效,服务于生态保护红线综合管理和保障区域生态安全,成为普遍关注的热点问题之一。针对已有的区域生态保护成效评估案例的不足,基于划定生态保护红线是为保障国家和区域生态安全的基本认知,围绕着生态保护红线“生态功能不降低、面积不减少、性质不改变”的管控目标,以生态保护红线对区域生态系统保护作用为主要出发点,提出生态保护成效评估框架和指标方法。生态保护成效评估以生态系统类型构成和生态系统服务功能为内容主线,通过多维度时空尺度拓展,耦合分析生态保护红线内外、实施前后的生态状况变化,综合评估生态保护红线对保障区域生态安全的贡献和改善区域生态状况的作用。进而,可以关联分析可能引起生态保护红线生态状况变化的管控政策、制度和其他间接驱动因素,评估政策实施成效评估。实证上选择海南省生态保护红线和广东省严格控制区为案例进行了讨论。  相似文献   

Li₂SO₄溶液中离子间的缔合相互作用:基于密度泛函理论和分子动力学模拟的研究   总被引：1，自引：1，他引：0  

胡俊  夏斐斐  杨凤丽  郑纯智  房春晖  曾德文  易海波 《盐湖研究》2018,26(1):39-47

基于密度泛函理论,使用B3LYP/aVDZ方法对[Li_2SO_4(H_2O)_n]~0(n=0~10、18)水合团簇的结构和性质进行了系统地研究,并结合Car-Parrinello分子动力学(CPMD)模拟了不同浓度的Li_2SO_4溶液结构,目的在于理解在Li_2SO_4溶液中离子间缔合相互作用及可能存在的物种。研究发现,对于[Li_2SO_4(H_2O)_n]~0(n=0~10、18)水合团簇,双配位单齿螯合接触离子对结构比双配位双齿螯合接触离子对结构更稳定,溶剂共享离子对结构最不稳定。同时,CPMD模拟结果表明,在3.09和3.17 mol/kg的Li_2SO_4溶液中,双配位单齿螯合接触离子对结构仍然是主要物种。以上结果表明在饱和的Li_2SO_4溶液(3.16 mol/kg)中,Li~+和SO_4~(2-)离子间的相互缔合作用主要以双配位单齿螯合接触离子对结构的物种存在,而具有双配位双齿螯合离子对结构的物种占少数,溶剂共享离子对结构几乎不存在。  相似文献   

Generating urban road intersection models from low-frequency GPS trajectory data   总被引：1，自引：0，他引：1  

Min Deng  Jincai Huang  Huimin Liu  Luliang Tang  Jianbo Tang 《International journal of geographical information science》2018,32(12):2337-2361

Detailed real-time road data are an important prerequisite for navigation and intelligent transportation systems. As accident-prone areas, road intersections play a critical role in route guidance and traffic management. Ubiquitous trajectory data have led to a recent surge in road map reconstruction. However, it is still challenging to automatically generate detailed structural models for road intersections, especially from low-frequency trajectory data. We propose a novel three-step approach to extract the structural and semantic information of road intersections from low-frequency trajectories. The spatial coverage of road intersections is first detected based on hotspot analysis and triangulation-based point clustering. Next, an improved hierarchical trajectory clustering algorithm is designed to adaptively extract the turning modes and traffic rules of road intersections. Finally, structural models are generated via K-segment fitting and common subsequence merging. Experimental results demonstrate that the proposed method can efficiently handle low-frequency, unstable trajectory data and accurately extract the structural and semantic features of road intersections. Therefore, the proposed method provides a promising solution for enriching and updating routable road data.  相似文献   

Geographical Environment for the Safe Production of Food     

WANG Li  XU Yuefeng  KONG Chang  MENG Min  WANG Wuyi 《资源与生态学报(英文版)》2018,9(1):13-21

Food is essential for human survival, but harmful, toxic substances in food damage and threaten human health. Food production is inseparable from the place where the food is produced; that is, from the geographical environment that consists of natural and human environments, two parts of a unified whole. China’s territory is vast and its geographical environment is complex and diverse. Food production patterns in different parts of the country vary significantly, as do local socio-economic and cultural conditions. Such differences have an enormous impact on food safety. Based on the geographical area where food is produced in China, this paper reveals the main environmental problems arising from industrial and agricultural production activities, and related risks for food safety and health. In concluding, we make some recommendations for countermeasures. The main food safety related environmental problems include the excessive application of chemical fertilizers and pesticides; high background levels of heavy metals; discharge of wastewater and heavy metals; and excessive use of additives and antibiotics in livestock and poultry breeding and aquatic products. All these issues can lead to huge risks for food safety and thus health. These are not simply scientific issues, but also political, economic and legal issues, as well as social problems that differ from region to region. Therefore, comprehensive studies are needed to identify risks to food safety and health hazards in different areas. Systematic and comprehensive risk assessments of health problems caused by changing ecosystems, environmental pollution, nutrition problems and lifestyle, and especially comprehensive risk assessments of regional environmental changes and health risks are needed. Measures based on an understanding of local conditions must be put forward to protect food safety and health, to strengthen multi-sectoral management, and to improve environmental quality  相似文献   

基于全视野数字图像的能见度估算方法          下载免费PDF全文

陆天舒  杨俊  邓敏  杜传耀 《应用气象学报》2018,29(6):701-709

基于全视野数字图像的能见度估算方法是将全视野图像大气透射率与大气能见度通过曲线拟合方法建立联系,得到估算模型进行能见度估算。首先通过历史全视野图像和对应时刻的大气能见度建立样本数据集,再利用暗原色先验理论获取全视野图像大气透射率,通过多项式拟合方法建立离散样本数据集中大气透射率与对应时刻大气能见度的关系,即全视野图像能见度估算模型,最终将所需估算时刻的数字图像输入估算模型进行能见度估算,得到大气能见度数值。结果表明:建立的基于全视野数字图像能见度估算模型在环境光照均匀时大气能见度估算值与能见度实测值有较好的一致性,可作为前向散射仪的补充观测方法,弥补其采样存在的局限性。  相似文献   

L波段探空仪湿度资料偏差订正及同化试验   总被引：1，自引：1，他引：0       下载免费PDF全文

郝民  龚建东  田伟红  万晓敏 《应用气象学报》2018,29(5):559-570

L波段探空仪观测资料是基础资料之一,无论在天气预报还是在数值天气预报中都起着重要作用,其资料质量直接影响数值模式同化分析及降水预报准确性。通过对我国3种常用的L波段探空仪观测湿度的偏差特性比较,研发适合该仪器的偏差订正方案,并在GRAPES同化系统中加以试验应用。结果表明:L波段探空仪湿度观测资料与ECMWF再分析湿度场比较有偏干现象。多种偏差订正方案订正结果显示:湿度偏差值比订正前减小,特别是在500 hPa以上层次减小明显。在GRAPES分析同化系统中使用Vomel偏差订正方案,分析偏差减小5%;预报模式个例和连续试验中湿度观测订正后预报降水更接近实况,预报降水检验评分显著提高,故该订正方案在实际应用中表现出积极的正效果。  相似文献   

Modulation of the Intensity of Nascent Tibetan Plateau Vortices by Atmospheric Quasi-Biweekly Oscillation     

Lun LI  Renhe ZHANG  Min WEN  Jianping DUAN 《大气科学进展》2018,35(11):1347-1361

The modulation of the intensity of nascent Tibetan Plateau vortices(ITPV) by atmospheric quasi-biweekly oscillation(QBWO) is investigated based on final operational global analysis data from the National Centers for Environmental Prediction. The spatial and temporal distributions of the ITPV show distinct features of 10–20-day QBWO. The average ITPV is much higher in the positive phases than in the negative phases, and the number of strong TPVs is much larger in the former,with a peak that appears in phase 3. In addition, the maximum centers of the ITPV stretch eastward in the positive phases,indicating periodic variations in the locations where strong TPVs are generated. The large-scale circulations and related thermodynamic fields are discussed to investigate the mechanism by which the 10–20-day QBWO modulates the ITPV. The atmospheric circulations and heating fields of the 10–20-day QBWO have a major impact on the ITPV. In the positive QBWO phases, the anomalous convergence at 500 hPa and divergence at 200 hPa are conducive to ascending motion. In addition, the convergence centers of the water vapor and the atmospheric unstable stratification are found in the positive QBWO phases and move eastward. Correspondingly, condensational latent heat is released and shifts eastward with the heating centers located at 400 hPa, which favors a higher ITPV by depressing the isobaric surface at 500 hPa. All of the dynamic and thermodynamic conditions in the positive QBWO phases are conducive to the generation of stronger TPVs and their eastward expansion.  相似文献   

台风“梅花”路径转折期间的结构特征分析与模拟     

袁敏  平凡  李国平 《大气科学》2018,42(5):1000-1012

利用多种资料对2011年第9号热带气旋“梅花”的两次路径转折过程进行诊断分析和数值模拟,结果表明:副热带高压、中纬度槽和越赤道气流等外部大环境场的变化对路径转向有影响,第一次路径转折期间,眼墙和螺旋云带分布变化不大;第二次路径转折前后,台风眼墙从双眼墙结构演变成明显的非对称结构,台风眼区发生了眼墙置换与合并,以及螺旋云带与眼墙合并过程。机制的定量分析表明:第一次转向期间,环境风场的纬向和经向分量对引导气流的贡献在83%以上,表明外部环境风场对其路径转向的影响较大,内部的风暴尺度风场对其路径转折的影响程度较小;第二次转向期间,风暴尺度场的纬向分量对引导引流贡献的百分比从23%上升到36%,经向分量对引导引流贡献的百分比介于35%~47%之间,表明内部非对称结构与外部大尺度环境流场对第二次路径转折都有影响。  相似文献   

苏州市大气PM_(2.5)中水溶性无机离子的源解析及其气象因子分析     

蔡敏  严明良  包云轩 《气象科学》2018,38(5):648-658

为了探明PM_(2.5)中水溶性无机离子的来源和气象因子对其浓度变化的影响,利用2012年2、5、8和11月苏州市PM_(2.5)中水溶性无机离子浓度和本站气象观测数据,分析了苏州市水溶性无机离子的时间变化特征,解析了当地PM_(2.5)中水溶性无机离子的主要来源,探讨了气象因素对离子组分的影响。结果表明:(1)苏州市PM_(2.5)中水溶性无机离子年均浓度大小依次为:SO_4~(2-)NO_3~-NH_4~+Na~+Cl~-K~+Ca~(2+)Mg~(2+)F~-;SO_4~(2-)、NH_4~+和NO_3~-为PM_(2.5)中最重要的3种水溶性无机离子物种,其总和占PM_(2.5)总质量浓度的50.9%。各离子的季节浓度特征均为冬季最高、夏季最低。(2)通过运用主成分分析法对苏州市PM_(2.5)中水溶性无机离子进行来源分类解析,发现第一类为二次污染源和生物质燃烧,其贡献率为32.84;第二类为道路扬尘及工业排放,其贡献率为19.99%;第三类为海盐污染,其贡献率为18.43%。(3)通过水溶性无机离子与气象条件的相关性分析发现,风向、风速和温度与水溶性无机离子浓度的相关性较显著,这三者是颗粒物浓度变化的主要影响因子。(4)利用HYSPLIT后向轨迹模式对外来污染物进入苏州市的轨迹进行聚类分析后发现:因受季风气候影响,苏州市外来污染物的输入路径存在明显的季节性变化特征,其中夏半年输送主径源自海上,冬半年主径源自内陆。  相似文献