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61.
关于《数字地图产品模式》标准的思考 总被引:1,自引:0,他引:1
基于《数字地图产品模式》(以下简称《标准》)研究成果,本文确定了《标准》的目的、编制理由和《标准》的用户;指出了《标准》在相关“参考模型”和“标准体系”中的位置;提出了《标准》的范围;分析了国内外同类标准及相关资料并介绍了其在《标准》中的应用概况;以列出修订前后标准目次和ISO19131草案目录结构对照表的方式,剖析了《标准》研究成果的结构框架;最终得出了《数字地图产品模式》标准的编制已经有了良好的开端和阶段性成果,应当抓紧时间完善成果,使研究成果尽快转化为国家标准的结论。 相似文献
62.
在分析地学数据特点和共享需求的基础上,阐述数据分类对于人们认识地球以及地学研究的重要性,并综述和评价了目前地学领域已有的各种分类研究。这些分类研究大致可归纳为探索型、应用型和综合型3种。由于地学数据应用的多学科交叉、多源异构等特性,分类系统很难满足系统性、一致性、易扩展性等原则。本文从数据发生的角度,探索新的数据分类方案,将地学数据分为器测数据、调查数据和过程数据三大类。从数据本质特征对其进行描述,学科应用仅作为数据的元数据对其标志,从而很好地消除了上述问题。此外,本文基于ISO19115地理信息核心元数据扩展模型,将地理信息元数据标准拓展到整个地学领域的数据描述,构建适应该地学数据分类方案的元数据体系。 相似文献
63.
基于中国现行城市规划体制的城市设计再思考 总被引:1,自引:0,他引:1
当前中国城市建设日新月异,但理想的城市空间仍然难以获得。问题的关键在于城市设计在中国现行城市规划体系下很难真正发挥作用。在回顾城市设计概念和内涵历史演进的基础上,总结了城市设计理论和实践在中国的发展概况,并重点分析了城市设计的现状和问题。在分析阐明城市设计与城市规划之间关系的基础上,明确指出在中国现行城市规划体制下必须走城市设计与城市规划相结合的一体化融合之路。最后从二者相结合的角度,从理论认识、法规体系、研究重点和方法途径等几个方面提出了中国城市设计的应对策略。 相似文献
64.
Deriving sediment quality guidelines (SQGs) for marine sediments is a difficult task. It will often be a trade off between reproducibility and relevance. One of the fundamental questions in ecotoxicology is to decide what one should measure to detect response in ecosystems exposed to human disturbance. In this paper we use field data to estimate threshold levels eliciting effects on soft bottom macrobenthos collected at different sediment types and depths on the Norwegian Continental Shelf and test these against natural levels occurring levels in reference conditions. SQGs are presented from multivariate analyses based on 121 gradients (represented with Ba, THC, Cd, Cu, Pb and Zn) incorporating more than 2000 species. Clear clusters with slightly disturbed communities related to contamination loadings were evident in 35% of the gradients. We found large variations in naturally occurring contamination concentrations and in the threshold levels electing effects on the fauna at different sediment types and depths. For example, an increase in depth of only 100 m can triple the Cu and Zn concentrations that elicit effects. Lowest background and threshold levels were found in shallow, sandy sediment. Our results suggest that current SQGs are too high. We hypothesised that setting a SQG of 4-times background concentrations will give sufficient protection for the fauna from metal contamination. The overall background concentration eliciting effects on metal was 3.6x. 相似文献
65.
66.
The East Asia-western North Pacific boreal summer intraseasonal oscillation simulated in GAMIL 1.1.1 总被引:1,自引:0,他引:1
We evaluate the performance of GAMIL1.1.1 in a 27-year forced simulation of the summer
intraseasonal oscillation (ISO) over East Asia (EA)-western North Pacific (WNP). The assessment
is based on two measures: climatological ISO (CISO) and transient ISO (TISO). CISO is the ISO
component that is phase-locked to the annual cycle and describes seasonal march. TISO is the
ISO component that varies year by year.
The model reasonably captures many observed features of the ISO, including the stepwise northward
advance of the rain belt of CISO, the dominant periodicities of TISO in both the South China
Sea-Philippine Sea (SCS-PS) and the Yangtze River Basin (YRB), the northward propagation of 30--50-day
TISO and the westward propagation of the 12--25-day TISO mode over the SCS-PS, and the zonal propagating
features of three major TISO modes over the YRB. However, the model has notable deficiencies. These
include the early onset of the South China Sea monsoon associated with CISO, too fast northward
propagation of CISO from 20oN to 40oN and the absence of the CISO signal south of 10oN,
the deficient eastward propagation of the 30--50-day TISO mode and the absence of a southward propagation
in the YRB TISO modes.
The authors found that the deficiencies in the ISO simulation are closely related to the model's biases in
the mean states, suggesting that the improvement of the model mean state is crucial for realistic
simulation of the intraseasonal variation. 相似文献
67.
北半球副热带—中纬度太平洋大气季节内扰动的纬向传播与东亚夏季旱涝 总被引:15,自引:0,他引:15
用时空滤波和Morlet小波方法,分析了1958—2000年夏季东亚(20°—45°N,110°—135°E)不同纬带(由南到北分为4个区域)的降水分别与太平洋同一纬带上大气30—60 d振荡(ISO)沿纬圈传播的关系及其成因机制。发现太平洋上经向风ISO向西传播的强或弱,是东亚夏季风区降水偏多或偏少的必要条件。对逐年夏季的分析表明,无论当年东亚夏季风强与否,在所划分的几个东亚季风区所有涝的年份里,太平洋同一纬带上大气ISO向西传播都明显较强,而在这些区域绝大多数旱的年份里,相应的ISO向西传播明显较弱。进一步分析发现,经向风ISO的纬向传播对应着大气经向型环流系统的移动,向西传影响东亚夏季风区降水的ISO有来自低纬中东太平洋东风流中的低频气旋(如副热带东风带中ISO的演变);也有来自中高纬度阿拉斯加湾及鄂霍次克海一带低频低压(如洋中槽)和高压(如阻塞高压和东北太平洋高压)的向南向西频散。因此东亚夏季旱涝不但与热带季风有关,而且与中东太平洋副热带东风系统中ISO的向西传播、中高纬度长波调整时低频扰动向西南经北太平洋副热带的传播密切相关。 相似文献
68.
The influence of intraseasonal oscillation (ISO) on TC genesis over the northwestern Pacific is studied through comparing analyses of the more and less TC years from 1979 to 2006. It is indicated that the ISO strongly affects the TC genesis. In the years for more TC genesis, the ISO is weak and propagates insignificantly in the area to the west of the Philippines, but the ISO is strong in the area to the east of the Philippines and propagates significantly northwestward. In this situation, the Walker cell shifts gradually westward from the tropical western Pacific to the tropical eastern Indian Ocean. Convergent winds appear in the lower atmosphere while divergent winds in the upper atmosphere, suggesting the presence of enhanced ascending flow over the 140-160°E region and a favorable condition for TC genesis. Moreover, in the years for less TC genesis, the ISO gradually becomes stronger in the area to the west of the Philippines and significant eastward propagation prevails from the eastern Indian Ocean to the area around 120°E; the ISO is weak in the area to the east of the Philippines. During these years, the Walker circulation gradually moved eastward, with convergent winds in the upper troposphere and divergent winds in the lower troposphere. Sinking motion was significant, unfavorable for the TC genesis over the Northwestern Pacific. 相似文献
69.
Yong LI Honghan CHEN Scott DIGEL Qunli DAI 《地学前缘》2005,12(Z1):88-94
加拿大联邦及Alberta省级环境导则为石油烃污染场地提供了多级环境标准及评价方法。其中二级环境标准评价,准许根据污染场地的实际条件计算土壤和地下水污染限值。环境导则限定了计算污染限值的模型和方法。这些模型大都是基于十分简化的野外条件的解析解模型,并根据导则规定的方法使用,以简化应用与审批程序。这些模型的用途和方法与一般通用地下水和土壤污染物运移模型有所不同,在实际运用时这些差别常常被忽略。同时,在复杂野外条件下运用这些模型时,经常遇到确定模型输入参数的困难。介绍了加拿大环境导则中计算污染场地土壤和地下水污染限值以保护地表水环境的模型方法,强调这些模型方法只适用于计算污染限值的特殊目的,不适用于预测污染物运移或套用一般模型拟和调参方法。结合具体计算实例,探索运用Monte Carlo方法评价与表示模型输入参数带来的不确定性。这种方法用参数变化区间(或概率分布)来表示输入参数的变化或不确定性,以求得具有统计意义的保险污染限值。这种方法简单易行,却将二级环境标准评价方法推广到较为复杂(更真实)的野外条件。 相似文献
70.
International Association of Geoanalysts'Protocol for the Certification of Geological and Environmental Reference Materials 总被引:2,自引:1,他引:2
Jean S. Kane Philip J. Potts Michael Wiedenbeck Jean Carignan Stephen Wilson 《Geostandards and Geoanalytical Research》2003,27(3):227-244
This protocol has been developed by the International Association of Geoanalysts to demonstrate procedures for the certification of geological and environmental reference materials to comply to the fullest extent possible with recommendations of the International Organisation for Standardisation (ISO Guide 35). A practical approach is described on the assumption that certifications will be normally be based on collaborative analysis programmes in which participating laboratories are preselected on the basis of performance in a proficiency testing programme or on the basis of other criteria of merit. 相似文献