大孔径闪烁仪和涡动相关仪观测显热通量之间的尺度关系   总被引：1，自引：0，他引：1  

卢俐  刘绍民  徐自为  白洁  王介民 《地球科学进展》2010,25(11):1273-1282

利用北京昌平小汤山2002年、2004年涡动相关仪和大孔径闪烁仪的观测数据,借助解析足迹模型计算的源区,分析均匀、非均匀下垫面上涡动相关仪和大孔径闪烁仪观测显热通量之间的差异和关系.结果表明:地表的均匀与非均匀性质,直接影响涡动相关仪和大孔径闪烁仪观测的显热通量的差异大小.在分析均匀、非均匀地表上2种仪器源区重叠面积及重叠区域内足迹值大小与观测通量值之间的关系后,构建一个非均匀地表上2台涡动相关仪与1台闪烁仪观测通量之间的尺度关系式.  相似文献   

景观格局与水土流失的尺度特征与耦合方法   总被引：11，自引：0，他引：11  

傅伯杰  徐延达  吕一河 《地球科学进展》2010,25(7):673-681

景观格局与生态过程的耦合研究是景观生态学研究的核心科学问题,也是综合自然地理学深化和发展的关键.尺度广泛存在于生态学现象中,尺度效应与尺度转换是景观生态学研究面临的挑战,探讨格局与过程之间相互作用机理与尺度特征是为解决尺度问题提供理论依据的必然途径.水土流失作为一种生态过程,是国内外颇为关注的生态问题.依据多种研究手段,在不同尺度上开展景观格局与水土流失的相互关系与尺度特征的研究,在分析景观格局的时空异质性、水土流失的影响因子与尺度效应的基础上,揭示流域景观格局与水土流失的耦合机理,发展尺度转换方法和景观格局-水土流失过程耦合模型,是完善景观生态学的理论基础,是为水土流失区生态建设提供科学依据的重要途径.  相似文献   

基于特征提取的光学影像和SAR影像自动配准     

彭芳媛  向常淦 《四川测绘》2009,32(6):257-262

针对现有的配准方法用于多光谱影像与SAR遥感影像配准时，存在受SAR图像斑纹噪声影像大、手工选取配准控制点精度低、利用图像景物特征配准时获取区域和边沿困难等问题，以SPOT5影像与RADARSATSAR影像配准进行实验，提出了一种利用改进的SIFT在提取的特征图像上寻找匹配点进行粗配准，然后利用交叉累积剩余熵作为相似性测度结合原始影像信息寻找光学特征图像的角点在SAR影像上的匹配点并进行精配准的方法，配准精度达到了子像素级水平。实验结果表明该方法对多源遥感影像有很强的适应性，配准精度高。  相似文献   

垂直网格计算频散性的研究   总被引：8，自引：2，他引：8       下载免费PDF全文

刘宇迪  朱红伟 《应用气象学报》2001,12(3):348-357

在线性斜压原始方程组的基础上, 从频率和群速方面讨论了几种垂直跳点网格和时间—垂直跳点网格的计算频散性, 并指出了出现错误群速的垂直尺度范围。以便为原始方程大气模式选取垂直网格提供指导。  相似文献   

阔克沙勒—吉萨尔地震活动时间的多重分形研究   总被引：2，自引：0，他引：2  

朱令人  周仕勇 《内陆地震》1993,7(4):319-324

应用多重分形的标度指数谱f(α)～α方法分析阔克沙勒——吉萨尔地区地震活动时间序列,发现一定范围内地震多重分形f(α)～α在大震前有明显的异常显示。说明f(α)谱研究地震的多重分形,简单、有效、能全面地描述地震时间分布这类不均匀分形集。  相似文献   

“A world in a grain of sand”: towards a reconceptualisation of geographical scale     

Richard Howitt 《The Australian geographer》1993,24(1):33-44

Difficulties in relating local scale change to broader dynamics of social and economic restructuring continue to be reflected in much geographical research. This paper argues that inadequate conceptualisations of geographical scale restrict the relevance of much research to the agenda of an applied peoples' geography. A framework which conceptualises geographical scale as dialectically and internally related to the totality of social relations, is proposed and discussed with examples from remote mining regions in Australia.  相似文献   

An observational study of 300 mb winds in the tropical belt. Part II: Dynamical interpretation     

N. D. Pyuzza  G. C. Asnani  P. M. R. Kiangi 《Pure and Applied Geophysics》1983,121(4):685-705

An estimate of the magnitudes of the absolute vorticity advection terms and the terms in the balance equation suggest that the use of the barotropic vorticity equation within 5 degrees of latitude of the equator is not very good and that the linear balance equation is as good as the nonlinear balance equation in the equatorial region. Zonal Fourier analysis has revealed that the contribution from planetary scale waves is much larger than that from synoptic scale waves, being more in the winter hemisphere than in the summer hemisphere. In classical scale analysis there must be a distinction in wavelength between the zonal and the meridional directions for planetary scale waves. This distinction does not appear to be necessary for synoptic scale waves.  相似文献   

Trace metals in sediments near offshore oil exploration and production sites in the Alaskan Arctic     

John?H.?TrefryEmail author  Robert?D.?Rember  Robert?P.?Trocine  John?S.?Brown 《Environmental Geology》2003,45(2):149-160

Increased offshore development in the Alaskan Arctic has stimulated interest in assessing potential impacts to the environment before the onset of any adverse effects. Concentrations of trace metals in sediments are used in this paper to provide one sensitive indicator of anthropogenic inputs from offshore activity over the past several decades. Sediments in coastal waters of the western Beaufort Sea are patchy with respect to sediment granulometry, organic carbon content, and concentrations of trace metals. However, results for surface sediments and age-dated cores show that nearly all samples contain natural concentrations of Ag, Ba, Be, Co, Cr, Cu, Hg, Ni, Pb, Sb, Tl, V and Zn, with metal/Al ratios that have been constant for many decades. Metal concentrations for incoming river-suspended matter compare well with sediment metal values and, along with vertical distributions in sediments, show no discernible diagenetic impacts that distort the sedimentary record for metals, except for Mn, As and possibly Cd. Slightly elevated concentrations of Ba, Hg, Ag, Sb and Zn were observed in a total of eight instances or in only 0.7% of the 1,222 data points for metals in surface sediments.  相似文献   

天文地质年代表与旋回地层学研究进展   总被引：12，自引：11，他引：12  

徐道一 《地层学杂志》2005,29(11):635-640

Rio等（2003）依据旋回地层学研究成果提出了“天文地质年代表”，旋回地层学研究是依据地层记录中的旋回与有关米氏旋回来确定地质时间。轨道（或天文）方法已被确定为建立2004年“国际地质年表”（由国际地层委员会确认）的重要方法之一（Gradstein等，2004）。我国在新近系、古近系、下侏罗统、二叠系等陆相沉积的旋回地层研究方面已取得一批成果。  相似文献   

There’s nothing inherent about scale: political ecology, the local trap, and the politics of development in the Brazilian Amazon     

J. Christopher Brown  Mark Purcell 《Geoforum》2005,36(5):607-624

This paper argues that research in political ecology would benefit from more explicit and careful attention to the question of scale and scalar politics. Although political ecologists have extensively considered scale as a methodological question, they have yet to develop an explicit theoretical approach to scale as an object of inquiry. We highlight one principal drawback to this underdeveloped approach to scale: what we call “the local trap” in which political ecologists assume that organization, policies, and action at the local scale are inherently more likely to have desired social and ecological effects than activities organized at other scales. Over the past 10 years or so, an increasingly sophisticated literature on scale has been developing among scholars in geography working in the political economy tradition. This literature has argued that scale is socially produced rather than ontologically given. Therefore, there is nothing inherent about any scale, and so the local scale cannot be intrinsically more desirable than other scales. We suggest that a greater engagement with this scale literature offers political ecology a theoretical way out of the local trap. As a first approximation of the kind of scalar analysis we advocate, we present a case study that examines the scalar politics that have shaped environmental change in the Brazilian Amazon.  相似文献