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徐新强 《大地测量与地球动力学》2015,35(5):853-856
针对EGM08重力场模型构建过程中存在的不足,提出用GOCE重力场模型替换EGM08模型的中低频部分,用剩余地形模型RTM拓展EGM08模型的甚高频信号。模拟分析表明,GOCE模型能大幅提高高程异常计算的精度,而RTM对高程异常的贡献也不可忽视。实测GPS/水准数据表明,GOCE模型对高程异常的贡献达到43%,而RTM也贡献了1cm的精度。 相似文献
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Genetic algorithm for fitting a mixed Bingham distribution to 3D orientations: a tool for the statistical and paleostress analyses of fracture orientations 
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下载免费PDF全文 Atsushi Yamaji 《Island Arc》2016,25(1):72-83
The clustering of fracture orientations is important for tectonic studies and for geotechnical engineering. In this study, a real‐coded genetic algorithm was adopted to fitting a mixed Bingham distribution to orientation data by maximizing the log‐likelihood function of the distribution. The maximization is a difficult problem, because the function has multimodality and singularity. It was found that the algorithm was effective for this problem. Given the orientations of dilational fractures, the present method determines not only the stress axes and stress ratio of each of the fracture groups but also the maximum non‐dimensionalized fluid pressure at the time of their formation. In addition, the software calculates the 95 % error ellipses of the concentration axes. The present method found that the orientations of ore veins of the Akenobe Mine, SW Japan, should be partitioned into three clusters. It is shown that two of the groups had distinctive Zn and Sn contents, and that the ore fluids had overpressures only slightly greater than the minimum principal stress at the time of the deposition of Zn‐ and Sn‐rich veins. 相似文献
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Observations of the North Equatorial Current,Mindanao Current,and Kuroshio current system during the 2006/07 El Niño and 2007/08 La Niña 总被引：1，自引：0，他引：1
Yuji Kashino Norievill España Fadli Syamsudin Kelvin J. Richards Tommy Jensen Pierre Dutrieux Akio Ishida 《Journal of Oceanography》2009,65(3):325-333
Two onboard observation campaigns were carried out in the western boundary region of the Philippine Sea in December 2006 and January 2008 during the 2006/07 El Niño and the 2007/08 La Niña to observe the North Equatorial Current (NEC), Mindanao Current (MC), and Kuroshio current system. The NEC and MC measured in late 2006 under El Niño conditions were stronger than those measured during early 2008 under La Niña conditions. The opposite was true for the current speed of the Kuroshio, which was stronger in early 2008 than in late 2006. The increase in dynamic height around 8°N, 130°E from December 2006 to January 2008 resulted in a weakening of the NEC and MC. Local wind variability in this region did not appear to contribute to changes in the current system. 相似文献
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Losses of pelagic diatom production resulting from silica limitation have not only been blamed for toxic algal blooms, but for the reduction in ability of coastal food webs to support higher trophic levels. Recent research has shown the importance of advective seepage water fluxes of dissolved silica (DSi) from freshwater marshes to pelagic waters during moments of riverine Si-limitation. In this study, we investigated the potential impact of recently installed new tidal areas along the Schelde estuary, located in former polder areas and characterized by so-called controlled reduced tidal regimes (CRT). Nine mass-balance studies were conducted in a newly constructed CRT in the freshwater Schelde estuary. During complete tidal cycles both DSi and amorphous silica (ASi) concentrations were monitored at the entrance culverts and in different habitats in the marsh. A swift DSi-delivery capacity was observed despite the shifted spatiotemporal frame of exchange processes compared to reference marshes. As silica-accumulating vegetation is not yet present, and difference with reference marshes’ deliveries is surprisingly small, we indicate diatomaceous debris and phytoliths to be the main silica source. Although further research is necessary on the driving forces of the different processes involved, restoration of former agricultural areas under CRT-regime provide the potential to buffer silica in the estuary. 相似文献
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为探究ASTER GDEMV3、SRTM1 DEM和AW3D30 DEM 3种开源DEM数据的高程精度,本文以高精度ICESat-2 ATLAS测高数据为参考数据,利用GIS统计分析、误差相关分析及数理统计对DEM的高程精度进行对比评价。结果表明：①AW3D30的质量最稳定;SRTM1 DEM在平原精度最高;在高原山地精度由高到低依次为AW3D30 DEM、ASTER GDEMV3、SRTM1 DEM。②DEM数据高程精度受地表覆盖影响较大,且与地形因素密切相关,在相同地表覆盖的两个研究区中DEM数据高程精度表现情况不一致,SRTM在平原地表覆盖下精度表现最好,平均误差为3.15 m,AW3D30 DEM在山地地表覆盖下精度表现最好,平均误差为7.61 m。③坡度对DEM数据的高程精度影响较大,在两个研究区3种DEM数据的高程误差均随坡度的增加而增加;坡向对DEM数据的高程精度影响较小,未发现明显的规律。 相似文献
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ICESat-2植被冠层高度和地表高程数据产品用于森林高度提取的效果评价 总被引：1，自引：0，他引：1
由美国宇航局（NASA）研制的新一代冰、云和陆地高程卫星（ICESat-2）于2018-09-15发射成功,其搭载的先进地形激光测高系统（ATLAS）采用微脉冲多波束光子计数激光雷达技术,可用于全球高程线采样数据的获取。目前公开发布了9种数据产品,其中包括植被冠层高度和地表高程数据产品（ATL08）,为全球森林结构参数的估算提供了新的契机。本文以美国宾夕法尼亚州斯奈德县和印度尼西亚西加里曼丹吉打邦为研究区,在温带森林和热带雨林两种不同的生态系统立地条件下,对 ICESat-2的ATL08数据产品用于森林高度估算的效果进行评价。首先建立了地形高程数据产品（ATL03）与ATL08数据产品的关联规则,以获取分别记录在这两种产品中的光子空间分布信息和分类信息;进而以机载小光斑激光雷达数据为参考,对ATL08数据产品的光子分类可靠性及其用于森林高度估算的准确性进行了分析评价。结果表明：（1）在温带森林情况下,ATL08数据产品提供的平均冠层高度和最大冠层高度与参考数据的相关系数（R2）分别为0.54和0.61,相对误差分别为16.78%和10.71%,表明ATL08数据产品的光子分类结果能够用于刻画森林冠层结构和林下地形;（2）在热带雨林情况下,到达地面的光子数量相较于温带森林明显减少,地面光子类型识别的可靠性低,ATL08数据产品提供的平均冠层高度和最大冠层高度与参考数据的相关系数（R2）分别为0.21和0.19;（3）森林覆盖度的增大会导致ATL08计算的冠层高度误差增大,热带雨林平均冠层高度的误差随着坡度增大有增大趋势,在坡度为0°—10°、10°—20°和20°—30°共3组情况下,误差分别为5.7 m、6.6 m和9.3 m。因此,在高森林覆盖度情况下,现有的ATL08数据产品难以直接用于森林高度的提取。 相似文献
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为进一步研究闪电活动特征,利用ADTD闪电定位资料、静止气象卫星葵花八号等气象资料,对2016年7月20日一次强对流天气过程中的闪电活动进行分析,探讨闪电活动与LAPS云分析场的关系,探索地闪资料在LAPS云分析中的应用。结果表明,地闪活动集中区域对应着强降水区,降水峰值与闪电活动峰值为重合的现象;大部分闪电发生处于对流云系影响范围之内且对应了中高层次的云顶性质;在LAPS云分析场中地闪活动频繁的区域,云柱更为厚实且出现了更为强烈的上升运动,水汽也更为充沛,闪电活动与积雨云的对应关系不仅可以反向验证卫星反演的云分类产品,也可以对LAPS三维云场进行订正和调整,并作为多源数据融合云分析的补充资料。 相似文献
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