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基于长江流域148个气象站1980—2017年的蒸发皿观测数据,将旋转经验正交函数(REOF)和模糊C均值聚类(FCM)相结合,对流域蒸发皿蒸发量(PE)进行分区,然后运用Modified Mann-Kendall检验和多元逐步回归等方法,分析各子区域PE的变化特征并识别其主要影响因子。结果表明:1) REOF的前4个空间模态显示流域PE存在5个主要的异常敏感区,基于这4个空间模态,流域PE在空间上可划分为9个子区域。2)在年尺度上,各区PE呈不同程度的增加趋势,其中中部盆地区上升速率最大(111.28 mm/10 a),西部高原区上升速率最小(12.5 mm/10 a);而在季节尺度上,秋、冬季流域PE呈显著上升趋势,春、夏季PE的变化具有明显的区域差异性,部分地区PE为下降趋势。3)影响PE变化的主要因子因地而异,但大多子区域的PE变化与平均气温和饱和水汽压差的变化显著相关。 相似文献
134.
基于第三次国土调查城镇村内部细化调查的工作要求和数据基础,梳理了城镇村调查边界划定、城镇村土地利用框架构建、城镇村土地利用图斑转绘、城镇村土地利用类型判定、外业补充调查等城镇村内部细化调查环节;归纳了1:2000基础地理信息数据、不动产登记数据、基础性地理国情监测数据等已有调查成果在各调查环节的数据转换利用方式,为城镇... 相似文献
135.
Chronology and Geochemistry of Volcanic Rocks in the Cretaceous Suifenhe Formation in Eastern Heilongjiang, China 总被引:3,自引:0,他引:3
JI Weiqiang XU Wenliang YANG Debin PEI Fuping JIN Ke LIU Xiaoming College of Earth Sciences Jilin University Changchun Jilin Bureau of Land Mineral Resources of Jilin Province Changchun Jilin The State Key Laboratory of Continental Dynamics Northwest University Xi ''an Shaanxi 《《地质学报》英文版》2007,81(2):266-277
Zircon U-Pb ages and geochemical data of volcanic rocks in the Suifenhe Formation in eastern Heilongjiang Province are reported, and their petrogenesis is discussed in this paper. The Suifenhe Formation mainly consists of basalt, andesite, and dacite. Zircon from andesite and dacite are euhedral in shape and show typical oscillatory zoning with high Th/U ratios (0.18-0.57), implying its magmatic origin. Zircon U-Pb dating results by laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) indicate that the 206Pb/238U ages of zircons from andesite range within 105-106 Ma, yielding a weighted mean age of 105.5±0.8 Ma (n=14), and that 206Pb/238U ages of zircons from dacite are between 90-96 Ma, yielding a weighted mean age of 93.2±1.3 Ma (n =13). The volcanic rocks from the Suifenhe Formation are subalkaline series and show a calc-alkaline evolutionary trend with SiO2 content of 47.69%-65.47%, MgO contents of 1.42%-6.80% (Mg#= 45-53), and Na2O/K2O ratios of 1.83-3.63. They are characterized by enrichment in large ion lithophile elements (LILE) and light-rare-earth elements (LREE), depletion in heavy rare earth elements (HREE) and high field strength elements (HFSE) (e.g., Nb, Ta, Ti), and low initial 87Sr/86Sr ratios (0.7041-0.7057) and positiveεNd(t) values (039-4.08), implying that they could be derived from a depleted magma source. Taken together, these results suggest that the primary magma of the volcanic rocks might originate from partial melting of the mantle wedge metasomatized by fluids derived from subducted slab under a tectonic setting of active continental margin. 相似文献
136.
YANG Xinglian ZHU Maoyan GUO Qingjun ZHAO Yuanlong 《《地质学报》英文版》2007,81(2):194-203
Secular variations of carbon isotopic composition of organic carbon can be used in the study of global environmental variation, the carbon cycle, stratigraphic delimitation, and biological evolution, etc. Organic carbon isotopic analysis of the Nangao and Zhalagou sections in eastern Guizhou reveals a negative excursion near the Precambrian-Cambrian boundary that correlates with a distinct carbonate carbon isotopic negative excursion at this boundary globally. Our results also demonstrate that several alternating positive and negative shifts occur in the Meishucunian, and an obvious negative anomaly appears at the boundary between the Meishucunian and Qiongzhusian. The isotope values are stable in the middle and lower parts but became more positive in the upper part of the Qiongzhusian. Evolution of organic carbon isotopes from the two sections in the deepwater facies can be well correlated with that of the carbonate carbon isotopes from the section in the shallow water facies. Integrated with other stratigraphic tools, we can precisely establish a lower Cambrian stratigraphic framework from shallow shelf to deep basin of the Yangtze Platform. 相似文献
137.
区域数字地震台网实时速报系统研究 总被引:8,自引:2,他引:6
根据我国地震监测台网的发展趋势,提出了区域数字地震台网实时速报系统的发展目标,研究了实现这一目标应解决的实时数据流接收、震相自动识别、震相可靠性处理、实时地震定位、震相到时等值线实时绘制、地震震级的实时计算、地震动强度分布图的实时绘制等问题.我们编制了一套实时地震速报软件,实现了上述功能,并用福建数字地震台网记录的地震事件进行软件功能测试.测试结果表明:对于网内地震,软件处理结果基本达到中国地震局地震速报评比满分的要求,速报时间缩短至30~50 s.此外,通过实时仿真技术,系统可给出实际观测到的PGA、PGV、PGD等值线图,可以为应急救灾确定重灾区和有感范围提供帮助. 相似文献
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A strong Coriolis force in a rapidly rotating planet and star not only enforces two-dimensionality of fluid motion driven by thermal instabilities but also generates strong differential rotation even in the vicinity of the onset of instabilities. We derive an asymptotic solution describing convection-driven differential rotation in rotating, self-gravitating Boussinesq fluid spheres with the no-slip boundary condition, taking into account full spherical curvature and being valid for asymptotically small Ekman numbers. For the purpose of validating the asymptotic solution, the corresponding numerical analysis valid for large or small Ekman numbers is also carried out, showing a satisfactory agreement between the asymptotic and numerical solutions. 相似文献
140.
T. Y. Lee J. C. Huang L. Y. Liao C. S. Tzeng C. H. Yang P. K. Kalita C. P. Tung 《水文研究》2012,26(24):3635-3644
Reducing or stabilizing the stream temperature of ChiChiaWan Creek is a crucial work for Formosan Landlocked Salmon because ChiChiaWan Creek is the only one habitat for this endangered species. Planting trees in the riparian zone would be one of the alternatives. The purpose of this study was to evaluate the effects of several planting strategies on daily maximum stream temperature along the river. The results showed the effective vegetative shading angles should be more than 50° along ChiChiaWan Creek to reduce the direct solar radiation heating effectively. Upstream planting with 70° vegetative shading angle could be the most effective way among all the scenarios. However, this planting strategy could not improve the worst situations in summer because of the large solar elevation angles. The upstream planting in ChiChiaWan Creek was strongly recommended because the canopies could be easier to extend to totally cover the narrow width of river producing the most effective shades. Practicing the upstream planting with 90° vegetative shading angle can increase more than 1 km long suitable habitats for the endangered Salmon in summer. Alternatively, the west‐side planting scenario was the second effective way for temperature reduction. Our result provided a useful suggestion for the authorities in charge of saving the Formosan Landlocked Salmon, particularly under the stress of global warming. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献