遥感结合地面观测估算陆地生态系统蒸散发研究综述   总被引：2，自引：1，他引：1  

鱼腾飞  冯起  司建华  席海洋  陈丽娟 《地球科学进展》2011,26(12):1260-1268

地面观测和遥感模拟作为陆地生态系统蒸散发研究的2种基本手段,有着各自的优缺点且存在互补性。因此,有效地将遥感和地面观测站点资料相结合,探讨陆地生态系统蒸散发的时空分布规律及不同尺度转换理论与方法,实现蒸散耗水地面观测结果的尺度扩展和生态需水量估算成为普遍关注的焦点。从遥感与地面观测结合确定陆地生态系统蒸散发入手,论述目...  相似文献   

Mass-radius curve for extrasolar Earth-like planets and ocean planets     

C. Sotin  O. Grasset  A. Mocquet 《Icarus》2007,191(1):337-351

By comparison with the Earth-like planets and the large icy satellites of the Solar System, one can model the internal structure of extrasolar planets. The input parameters are the composition of the star (Fe/Si and Mg/Si), the Mg content of the mantle (Mg# = Mg/[Mg + Fe]), the amount of H₂O and the total mass of the planet. Equation of State (EoS) of the different materials that are likely to be present within such planets have been obtained thanks to recent progress in high-pressure experiments. They are used to compute the planetary radius as a function of the total mass. Based on accretion models and data on planetary differentiation, the internal structure is likely to consist of an iron-rich core, a silicate mantle and an outer silicate crust resulting from magma formation in the mantle. The amount of H₂O and the surface temperature control the possibility for these planets to harbor an ocean. In preparation to the interpretation of the forthcoming data from the CNES led CoRoT (Convection Rotation and Transit) mission and from ground-based observations, this paper investigates the relationship between radius and mass. If H₂O is not an important component (less than 0.1%) of the total mass of the planet, then a relation (R/REarth)=ab(M/MEarth) is calculated with (a,b)=(1,0.306) and (a,b)=(1,0.274) for ¹⁰⁻²MEarth<M<MEarth and MEarth<M<10MEarth, respectively. Calculations for a planet that contains 50% H₂O suggest that the radius would be more than 25% larger than that based on the Earth-like model, with (a,b)=(1.258,0.302) for ¹⁰⁻²MEarth<M<MEarth and (a,b)=(1.262,0.275) for MEarth<M<10MEarth, respectively. For a surface temperature of 300 K, the thickness of the ocean varies from 150 to 50 km for planets 1 to 10 times the Earth's mass, respectively. Application of this algorithm to bodies of the Solar System provides not only a good fit to most terrestrial planets and large icy satellites, but also insights for discussing future observations of exoplanets.  相似文献   

Outgassing of ordinary chondritic material and some of its implications for the chemistry of asteroids, planets, and satellites     

Laura Schaefer  Bruce Fegley Jr. 《Icarus》2007,186(2):462-483

We used chemical equilibrium calculations to model thermal outgassing of ordinary chondritic material as a function of temperature, pressure, and bulk composition and use our results to discuss outgassing on asteroids and the early Earth. The calculations include ∼1000 solids and gases of the elements Al, C, Ca, Cl, Co, Cr, F, Fe, H, K, Mg, Mn, N, Na, Ni, O, P, S, Si, and Ti. The major outgassed volatiles from ordinary chondritic material are CH₄, H₂, H₂O, N₂, and NH₃ (the latter at conditions where hydrous minerals form). Contrary to widely held assumptions, CO is never the major C-bearing gas during ordinary chondrite metamorphism. The calculated oxygen fugacity (partial pressure) of ordinary chondritic material is close to that of the quartz-fayalite-iron (QFI) buffer. Our results are insensitive to variable total pressure, variable volatile element abundances, and kinetic inhibition of C and N dissolution in Fe metal. Our results predict that Earth's early atmosphere contained CH₄, H₂, H₂O, N₂, and NH₃; similar to that used in Miller—Urey synthesis of organic compounds.  相似文献   

Flood-formed dunes in Athabasca Valles, Mars: morphology, modeling, and implications     

Devon M. Burr  Paul A. Carling  Nicholas Lancaster 《Icarus》2004,171(1):68-83

Estimates of discharge for martian outflow channels have spanned orders of magnitude due in part to uncertainties in floodwater height. A methodology of estimating discharge based on bedforms would reduce some of this uncertainty. Such a methodology based on the morphology and granulometry of flood-formed (‘diluvial’) dunes has been developed by Carling (1996b, in: Branson, J., Brown, A.G., Gregory, K.J. (Eds.), Global Continental Changes: The Context of Palaeohydrology. Geological Society Special Publication No. 115, London, UK, 165-179) and applied to Pleistocene flood-formed dunes in Siberia. Transverse periodic dune-like bedforms in Athabasca Valles, Mars, have previously been classified both as flood-formed dunes and as antidunes. Either interpretation is important, as they both imply substantial quantities of water, but each has different hydraulic implications. We undertook photoclinometric measurements of these forms, and compared them with data from flood-formed dunes in Siberia. Our analysis of those data shows their morphology to be more consistent with dunes than antidunes, thus providing the first documentation of flood-formed dunes on Mars. Other reasoning based on context and likely hydraulics also supports the bedforms' classification as dunes. Evidence does not support the dunes being aeolian, although a conclusive determination cannot be made with present data. Given the preponderance of evidence that the features are flood-formed instead of aeolian, we applied Carling's (1996b, in: Branson, J., Brown, A.G., Gregory, K.J. (Eds.), Global Continental Changes: The Context of Palaeohydrology. Geological Society Special Publication No. 115, London, UK, 165-179) dune-flow model to derive the peak discharge of the flood flow that formed them. The resultant estimate is approximately 2×10⁶ m³/s, similar to previous estimates. The size of the Athabascan dunes' in comparison with that of terrestrial dunes suggests that these martian dunes took at least 1-2 days to grow. Their flattened morphology implies that they were formed at high subcritical flow and that the flood flow that formed them receded very quickly.  相似文献   

地面激光扫描仪(TLS)加常数检定方法的研究     

刘东全 《测绘科学》2011,36(3):164-165

地面激光扫描仪是继GPS技术之后的重要技术进步,已经广泛地应用到各行各业.但国内目前对其误差源及其检定方法的重视不够,缺乏系统的研究,更缺乏规范化的检定方法.本文研究了地面激光扫描仪测距部分最重要的系统误差即加常数的检定方法,给出了检定方法、计算公式及精度要求.本文研究内容可以为今后起草地面激光扫描仪检定规程提供参考.  相似文献   

四川盆地钻孔温度测量及现今地热特征   总被引：19，自引：11，他引：8       下载免费PDF全文

徐明  朱传庆  田云涛  饶松  胡圣标 《地球物理学报》2011,54(4):1052-1060

基于四川盆地9口钻孔的稳态测温资料和297块岩石样品的热导率数据,报道了9个高质量的大地热流数据,提出了沉积地层岩石热导率系列柱.结合前人的数据资料,绘制了地温梯度和大地热流等值线图.四川盆地沉积地层的岩石热导率变化主要由岩性控制,与现今埋藏深度没有明显的相关性.盆地的地温梯度为17.7～33.3℃/km,平均值为22...  相似文献   

Importance of sampling across an assemblage of glacial landforms for interpreting cosmogenic ages of deglaciation     

Arjen P. Stroeven  Derek Fabel  David Fink  Torbjørn Dahlgren 《Quaternary Research》2011,76(1):148-156

Deglaciation chronologies for some sectors of former ice sheets are relatively poorly constrained because of the paucity of features or materials traditionally used to constrain the timing of deglaciation. In areas without good deglaciation varve chronologies and/or without widespread occurrence of material that indicates the start of earliest organic radiocarbon accumulations suitable for radiocarbon dating, typically only general patterns and chronologies of deglaciation have been deduced. However, mid-latitude ice sheets that had warm-based conditions close to their margins often produced distinctive deglaciation landform assemblages, including eskers, deltas, meltwater channels and aligned lineation systems. Because these features were formed or significantly altered during the last glaciation, boulder or bedrock samples from them have the potential to yield reliable deglaciation ages using terrestrial cosmogenic nuclides (TCN) for exposure age dating. Here we present the results of a methodological study designed to examine the consistency of TCN-based deglaciation ages from a range of deglaciation landforms at a site in northern Norway. The strong coherence between exposure ages across several landforms indicates great potential for using TCN techniques on features such as eskers, deltas and meltwater channels to enhance the temporal resolution of ice-sheet deglaciation chronologies over a range of spatial scales.  相似文献   

The bulk composition of Mars     

G. Jeffrey Taylor 《Chemie der Erde / Geochemistry》2013

An accurate assessment of the bulk chemical composition of Mars is fundamental to understanding planetary accretion, differentiation, mantle evolution, the nature of the igneous parent rocks that were altered to produce sediments on Mars, and the initial concentrations of volatiles such as H, Cl and S, important constituents of the Martian surface. This paper reviews the three main approaches that have been used to estimate the bulk chemical composition of Mars: geochemical/cosmochemical, isotopic, and geophysical. The standard model is one developed by Wänke and Dreibus in a series of papers, which is based on compositions of Martian meteorites. Since their groundbreaking work, substantial amounts of data have become available to allow a reassessment of the composition of Mars from elemental data, including tests of the basic assumptions in the geochemical models. The results adjust some of the concentrations in the Wänke–Dreibus model, but in general confirm its accuracy. Bulk silicate Mars has roughly uniform depletion of moderately volatile elements such as K (0.6 × CI), and strong depletion of highly volatile elements (e.g., Tl). The highly volatile elements are within uncertainties uniformly depleted at about 0.06 CI abundances. The highly volatile chalcophile elements are likewise roughly uniformly depleted, but with more scatter, with normalized abundances of 0.03 CI. Bulk planetary H₂O is much higher than estimated previously: it appears to be slightly less than in Earth, but D/H is similar in Earth and Mars, indicating a common source of water-bearing material in the inner solar system. K/Th ranges from ∼3000 to ∼5000 among the terrestrial planets, a small range compared to CI chondrites (19,000). FeO varies throughout the inner solar system: ∼3 wt% in Mercury, 8 wt% in Earth and Venus, and 18 wt% in Mars. These differences can be produced by varying oxidation conditions, hence do not suggest the terrestrial planets were formed from fundamentally different materials. The broad chemical similarities among the terrestrial planets indicate substantial mixing throughout the inner solar system during planet formation, as suggested by dynamical models.  相似文献   

油气超长运移距离   总被引：6，自引：1，他引：5  

朱光有  杨海军  张斌  苏劲  张超  张科  刘永福  卢玉红 《岩石学报》2013,29(9):3192-3212

塔里木盆地塔北地区广泛分布着来自于库车坳陷的陆相油气,其运移距离超过100km,是一个比较典型的油气超长距离运移实例。本文在结合油气勘探基础资料的基础上,通过对出油井的详细地球化学研究,综合油气运移条件的分析,探讨了油气超长运移的地质条件与动力机制。研究认为,在哈拉哈塘和英买力南部地区白垩系砂岩储层中发现的油气来源于北部库车坳陷的三叠系湖相烃源岩,成藏时间在5~3Ma;油气主要通过断裂沟通不整合面以及白垩系巴西改组的砂体进行长距离侧向运移,运移的直线距离达到110~130km。研究发现,库车坳陷三叠系优质烃源岩短期内快速熟化并高效排烃,为油气长距离运移提供了充沛的油源和驱动力条件;白垩系巴西改组油层在致密顶底板岩层的封堵约束作用下,油气沿着宽缓斜坡上大面积分布的连通砂体呈面状发生长距离运移,沿途缺少大型圈闭拦截和聚油,油气损失相对较少,所以油气在通畅的运移道路上持续向南推进,这是该区油气发生超长运移的主要动力机制。超长的运移距离,与该区低幅度宽缓的斜坡构造背景和良好的输导通道密切相关,因此,在已发现白垩系出油井点以南更远地区还将不断会有陆相油的新发现;在油气运移经过的地区,白垩系内只要存在圈闭,均可形成油藏,因此,低幅度构造圈闭与岩性地层圈闭所形成的中小型油气田群将作为今后勘探的主要目标。  相似文献   

Automated registration of dense terrestrial laser-scanning point clouds using curves     

《ISPRS Journal of Photogrammetry and Remote Sensing》2014

This paper proposes an automatic method for registering terrestrial laser scans in terms of robustness and accuracy. The proposed method uses spatial curves as matching primitives to overcome the limitations of registration methods based on points, lines, or patches as primitives. These methods often have difficulty finding correspondences between the scanned point clouds of freeform surfaces (e.g., statues, cultural heritage). The proposed method first clusters visually prominent points selected according to their associated geometric curvatures to extract crest lines which describe the shape characteristics of point clouds. Second, a deformation energy model is proposed to measure the shape similarity of these crest lines to select the correct matching-curve pairs. Based on these pairs, good initial orientation parameters can be obtained, resulting in fine registration. Experiments were undertaken to evaluate the robustness and accuracy of the proposed method, demonstrating a reliable and stable solution for accurately registering complex scenes without good initial alignment.  相似文献