Thermodynamic processes of lake ice and landfast ice around Zhongshan Station, Antarctica     

LEI RuiBo  LI ZhiJun  ZHANG ZhanHai  CHENG YanFeng 《极地研究(英文版)》2011,(3):143-152

  相似文献   

图形化的地学耦合建模环境与原型系统设计     

张子民  周英  李琦  毛曦 《地球信息科学学报》2011,13(1):48-57

耦合建模是近年来地学研究使用的重要方法.建模框架是应用较多的一类地学耦合建模环境.由于要求研究者完成耦合模型的程序编码,在一定程度上降低了它的可用性,同时也带给使用者更多的负担.本文以建模框架ESMF作为基础,对构建完全图形化的地学耦合建模环境中的问题和解决方法进行探讨.主要包括:根据确定的耦合模式及其隐含的模型调用和...  相似文献   

GPS接收机仪器偏差的长期变化特性分析   总被引：3，自引：1，他引：2  

周东旭  袁运斌  李子申  刘西凤 《大地测量与地球动力学》2011,31(5):114-118

基于欧洲定轨中心2001-2009年发布的部分IGS测站接收机仪器偏差估值,分析了不同类型接收机DCB的长期变化特性.结果表明:各类接收机DCB的长期时变特征均具备一定的周期性,其中以月和年周期最为明显;接收机DCB的长期变化中还存在一定的波动,部分接收机DCB的稳定性随时间积累逐渐变差,甚至存在偏移.  相似文献   

空间分析中几种插值方法的比较研究   总被引：2，自引：0，他引：2  

刘光孟  汪云甲  张海荣  王栋 《地理信息世界》2011,9(3):41-45

针对常用的空间插值方法在精度分析方面比较的不足,从地质统计学、数学函数和几何方法方面分别选取普通克里金插值法、三次样条函数法和距离权重倒数法进行插值精度的比较与分析。文章分析了各个方法的优缺点和局限性,选取疏密差异较大的均匀和不均匀离散点数据进行实验,利用三次趋势面模型和MATLAB,ArcGIS,GS+Version...  相似文献   

湖泊沉积物的矿物组成、成因、环境指示及研究进展   总被引：5，自引：1，他引：4  

金章东 《地球科学与环境学报》2011,33(1):34-44,77

湖泊沉积物是不同地质、气候、水文条件下各类碎屑、黏土、自生/生物成因矿物以及有机物质等的综合体。沉积矿物蕴含着丰富区域和全球环境演变信息,如湖水的化学组成、流域构造、气候、水文以及人类活动的相互作用等。相关信息可以赋存在矿物外部微形貌、内部微结构、化学组成、物理和化学性质、同位素组成、谱学特征、成因以及共生组合等方面。因此,湖泊科学的许多关键课题都离不开矿物学,特别是在利用湖泊沉积物进行区域及过去全球变化研究中,深入的机理研究归根到底都要涉及矿物学,如流域化学风化作用、粒度组成、生物壳体化学组成、测年材料的选择等。然而,由于湖泊沉积物中矿物的多源性、复杂性,如何有效提取和解译其中的环境信息,是一项长期困扰研究者的课题,湖泊沉积矿物学的研究往往被许多研究者所忽视,中国的相关研究也较为薄弱。笔者综述了湖泊沉积物中碎屑、黏土、自生/生物矿物的矿物组合、特征、成因在(古)环境反演中的作用及最新研究进展,提出除了继续加强对湖泊沉积物中矿物来源、成因和古环境示踪的深入研究以外,矿物相间的转变及其对湖水和孔隙水组成的响应、一些非晶质或隐晶质及低丰度矿物相在湖泊化学和动力学中的作用也是很有潜力的研究领域,最后提出了研究中存在的一些问题、面对的挑战以及对研究前景的展望。  相似文献   

生态补偿对贫困农户影响的研究思路——以甘肃省陇南市退耕还林项目为例     

王立安 《广东海洋大学学报》2011,31(2)

随着生态环境问题的日益突出,生态补偿现已成为解决此问题的有效手段之一。基于生态补偿项目社会公平性考虑和项目实施的客观扶贫效果,有关贫困农户的研究成为近年来国外生态补偿研究中普遍关注的议题。在分析生态补偿原理的基础上,以甘肃省陇南市为例,提出研究生态补偿对贫困农户影响的框架及其具体的测度方法,并总结了该类区域生态补偿的设计中亟需改善的问题。  相似文献   

《国际汉语能力标准》中值得商榷的地方——兼与《欧洲语言共同参考框架:学习、教学、评估》比较     

徐海冰  程燕 《广东海洋大学学报》2011,31(5):91-95

通过对《国际汉语能力标准》的考察,同时与《欧洲语言共同参考框架:学习、教学、评估》比较,发现《国际汉语能力标准》存在三个方面的问题:结构不合理、内容有缺失以及评级等级标准不科学,以此研究结果为《国际汉语能力标准》的修订提供参考。  相似文献   

Geomorphic Controls on Historical Channel Planform Changes on the Lower Pages River,Hunter Valley,Australia     

Wayne D. Erskine 《The Australian geographer》2011,42(3):289-307

Historical planform changes in a 14.7 km reach of the lower Pages River were determined to assess whether they were autogenic (inherent in the river regime) or allogenic (driven by external changes) in nature so as to better focus river management activities and river restoration works. A pattern metamorphosis or complete change in river morphology occurred during the February 1955 flood. The peak discharge of this event exceeded the slope and grain size (intrinsic) threshold for braiding, converting the narrow, slightly sinuous stream to a wide, braided-like river. Five subsequent intrinsic threshold-exceeding floods did not cause further bar development because an over-widened channel already existed. Autogenic channel planform changes included sinuosity variations due to lateral migration and pattern metamorphosis due to the exceedance of a discharge–slope–grain size geomorphic threshold. Allogenic channel planform changes included: (1) realignment/channel straightening and artificial cutoffs by river training works; (2) lateral migration by increased bank erodibility due to riparian vegetation clearing; (3) lateral migration by the operation of a transitive geomorphic threshold involving the onset of a flood-dominated regime after 1946 and increased catchment runoff after 1830 due to large-scale clearing of catchment vegetation; and (4) the occurrence of a large flood in February 1955. Multiple forcing factors have clearly caused historical channel planform changes of the lower Pages River, making the design of river management and restoration works a complex matter outside the scope of simple formulaic protocols.  相似文献   

Conifer stomata analysis in paleoecological studies on the Loess Plateau: An example from Tianchi Lake, Liupan Mountains     

K. ZhangY. Zhao  X.L. Guo 《Journal of Arid Environments》2011,75(11):1209-1213

The identification of fossil conifer stomata was conducted from a lake sedimentary sequence on the Liupan Mountains, southwestern Loess Plateau, in order to reconstruct detailed forest history and assess the potential of using stomata as a supplement to pollen analysis to determine the local presence of conifers over the last 3200 years. The pollen has already been analyzed in our previous study. Reference conifer stomata were prepared for the fossil stomata identification and demonstrate that the conifer stomata could be identified to at least genus level. Our stomata and pollen results reveal three clear stages of the forest recession during the late Holocene: mixed conifer-deciduous forest, steppe-forest and steppe. Combined stomata and pollen results confirm the local presence of conifer trees (Abies and Pinus) in the vicinity of the Tianchi Lake. Abundant Abies trees existed during 3200-2200 cal yr BP. Then it decreased and finally demised at ca.210 cal yr BP. Pinus trees have been continuously present with very low abundance throughout the late Holocene. Application of comprehensive studies comprising both stomata and pollen analyses allowed a detailed determination of the stages of conifer trees presence in the vicinity of the Tianchi Lake. Our study suggests that the analysis of fossil stomata is a valuable methodological tool for the provision of unambiguous evidence of the past local presence of the coniferous taxa in this region.  相似文献   

Environmental zonation across the Australian arid region based on long-term vegetation dynamics     

E.F. Lawley  M.M. LewisB. Ostendorf 《Journal of Arid Environments》2011,75(6):576-585

Zonation of landscapes is generally based on broad scale biophysical data, field surveys, imagery and expert knowledge. Such zonation represents a static view of the environment and does not reflect dynamics and function. Arid environments are however often highly dynamic, and spatial and temporal patterns may be expressed over long periods of time. These dynamics need to be understood for management. Our aim is to understand the dynamics and functional response of vegetation in the Australian arid zone, and use this to inform and potentially improve the currently employed stratification. Principal component analysis of 25 years of satellite imagery identified underlying factors influencing patterns of arid vegetation growth, and regions of similar long-term response. Dominant factors of variation were identified as the spatial distribution of total vegetation growth, seasonality of growth, magnitude of seasonal variability in growth, and regularity of variation in growth. Additional variation resulted from episodic vegetation growth of limited spatial extent and duration. Classes expressing these functional components were compared with the existing biogeographical regions, revealing agreement in some instances, and in other cases adding information previously not available. The study demonstrates a new approach to Australian landscape zonation that has potential for much wider application.  相似文献