Spatial dynamics of estuarine water surface temperature from airborne remote sensing     

Richard D. Hedger  Tim J. Malthus  Andrew M. Folkard  Peter M. Atkinson 《Estuarine, Coastal and Shelf Science》2007,71(3-4):608-615

This paper examines the applicability of airborne remote sensing to the characterization and quantification of the spatial dynamics of water surface temperature (WST) within estuaries. For this, a series of successive airborne Thematic Mapper thermal images was acquired of Kirkcudbright Bay, an estuary in the United Kingdom, on two dates. Spatial dynamics were determined by two techniques: (1) qualitatively, which involved interpreting features ‘by eye’; and (2) by the velocimetric technique of maximum cross correlation (MCC). Qualitatively, complex spatial dynamics were identified over a wide range of spatial and temporal scales, associated with the creation and dissipation of eddies, and the convergence and divergence of fronts, all of which were superimposed on the synoptic tidal flow. MCC was effective for producing synoptic velocity fields, but the minimum cell size was constrained by image noise, limiting the ability to analyze small-scale spatial dynamics. The effectiveness of MCC was related to the ratio of spatially correlated variance to spatially independent variance, as estimated from the variogram. Suggestions for optimizing the application of airborne remote sensing to estuarine spatial dynamics are presented.  相似文献   

河口水Cu²⁺, Zn²⁺的分析、形式、分布、毒性与生态环境   总被引：4，自引：1，他引：4  

顾宏堪 《海洋与湖沼》1996,27(3):336-339

生物毒性实验Ｃｕ＾２＋，Ｚｎ＾２＋等浓度与生物死亡率相关模式表明，海水中加入的Ｃｕ＾２＋，Ｚｎ＾２＋等浓度逐渐增高，生物死主恨率相应增高，同一浓度下，死亡率随时间（２４，４８，７２，９６ｈ）的增加逐步增高，实验加入Ｃｕ＾２＋仅１μｇ／Ｌ和Ｚｎ＾２＋仅５μｇ／Ｌ本底浓度时，其毒性即已开始遵循相关模式。因此，比天然水含量仅高１，２倍的Ｃｕ＾２＋，Ｚｎ＾２＋离子的污染及毒性，就足以破坏鱼虾在河口的产卵，  相似文献   

Mantle plumes link magnetic superchrons to phanerozoic mass depletion events   总被引：2，自引：0，他引：2  

Vincent Courtillot  Peter Olson 《Earth and Planetary Science Letters》2007,260(3-4):495-504

The four most recent large mass extinction events in the Phanerozoic – the Cretaceous–Tertiary (KT), the Triassic–Jurassic (TJ), and the Permo-Triassic (PT) and Guadalupian–Tatarian (GT) doublet – are associated with a major flood basalt eruption, with the timing of peak volcanic activity corresponding within measurement uncertainties to the extinction event. Three magnetic superchrons precede the four largest Phanerozoic extinctions. The Cretaceous Long Normal Superchron (duration  35 Myr) precedes the KT and the Permian Kiaman Long Reversed Superchron ( 50 Myr) precedes the PT–GT doublet. In addition, the newly recognized Ordovician Moyero Long Reversed Superchron ( 30 Myr) precedes the end-Ordovician extinction event. There is a 10–20 Myr delay between the end of each superchron and the subsequent mass depletion event, both of which represent distant outliers from their respective populations. We propose that deep mantle plumes link these seemingly unrelated phenomena. Long-term ( 200 Myr) variations in mantle convection possibly associated with the Wilson cycle induce temporal and spatial variations in heat flow at the core–mantle boundary. Polarity reversals are frequent when core heat flow is high and infrequent when it is low. Thermal instabilities in the D”-layer of the mantle increase core heat flow, end the magnetic superchron, and generate deep mantle plumes. The plumes ascend through the mantle on a 20 Myr time scale, producing continental flood basalt (trap) eruptions, rapid climatic change, and massive faunal depletions.  相似文献   

福建九龙江口红树林造林遇到的问题   总被引：4，自引：1，他引：4  

薛志勇 《湿地科学与管理》2006,2(3):54-57

中国的红树林在过去50年里面积锐减了近70%,恢复和发展红树林迫在眉睫,红树林人工造林是必由之路。福建九龙江口湿地资源丰富,然而在红树林造林上却遇到了一些问题,这些问题阻碍了九龙江口红树林的恢复和发展,应该引起相关部门的关注。  相似文献   

Shear-wave splitting around the Eifel hotspot: evidence for a mantle upwelling   总被引：1，自引：0，他引：1  

K. T. Walker  G. H. R. Bokelmann †  S. L. Klemperer  G. Bock ‡ 《Geophysical Journal International》2005,163(3):962-980

  相似文献   

Upper mantle S-wave speed heterogeneity and anisotropy beneath the North Atlantic from regional surface wave tomography: the Iceland and Azores plumes     

S. Pilidou  K. Priestley  Ó. Gudmundsson  E. Debayle 《Geophysical Journal International》2004,159(3):1057-1076

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试论体视学方法在地球科学中的某些应用   总被引：1，自引：1，他引：0  

郭履灿 《CT理论与应用研究》1999,8(3):10-14

本文论述了体视学的科学含义和方法的某些特征。体视学是定量研究人体或生物器官、材料、介质或物体三维组织结构的科学分支：其广泛的含义可以理解为：由天空对象的低维信息和数据,用以获取研究对象的高维（三维或更高）性质或图像特征,包括它们所涉及的定量参数之间的数学关系,并中以应用的一门交叉性科学分支。根据当前科学的发展水平,例举出体视学方法在地球科学中有以下几方面的应用：（１）在监测火山岩浆囊活动中的作用;  相似文献   

The aerodynamic behaviour of volcanic aggregates   总被引：1，自引：1，他引：0  

S J Lane  J S Gilbert  M Hilton 《Bulletin of Volcanology》1993,55(7):481-488

A large proportion of solid material transported within the atmosphere during volcanic eruptions consists of particles less than 500 m in diameter. The majority of these particles become incorporated into a wide range of aggregate types, the aerodynamic behaviour of which has not been determined by either direct observation or in the laboratory. In the absence of such data, theoretical models of fallout from volcanic plumes make necessarily crude assumptions about aggregate densities and fall velocities. Larger volcanic ejecta often consists of pumice of lower than bulk density. Experimental data are presented for the fall velocities of porous aggregates and single particles, determined in systems analogous to that of ejecta falling from a volcanic plume. It is demonstrated that the fall of aggregates may be modelled in identical fashion to single particles by using a reduced aggregate density dependent on the porosity, and a size corresponding to an enclosing sphere. Particles incorporated into aggregates attain a substantially higher fall velocity than single particles. This is due to the larger physical dimensions of the aggregate, which overcomes the effect of lower aggregate density. Additionally, the internal porosity of the aggregate allows some flow of fluid through the aggregate and this results in a small increase in fall velocity. The increase in fall velocity of particles incorporated into aggregates, rather than falling individually, results in the enhanced removal of fine material from volcanic plumes.  相似文献   

Holocene stratigraphy-of the Lower Ganges-Brahmaputra River delta in Bangladesh     

Sirajur Rahman KHAN  Md Badrul ISLAM 《Frontiers of Earth Science》2008,2(4):393-399

Major part of the Holocene Ganges-Brahmaputra delta occupies the southern and southwestern part of Bangladesh with a smaller part extending beyond the international boundary in the west. Five facies assemblages are documented in the lower deltaic plain in five different depositional environments: levee or levee complex, bil or depression, abandoned meander belt, interdistributary plain and estuarine plain. The thickness of the Holocene sediments ranges from 30 m to 70 m in the deltaic plain, usually floored by the Pleistocene stiff clays, with the exception of the abandoned meander belt deposit where Holocene channel sand deposited directly on the Pleistocene sand. Radiocarbon dates indicate that low-rate sedimentation has occurred in the northern part, where 4-6 m thick sediments were deposited since the mid-Holocene, whereas 10-30 mthick sediments were deposited in the southern part during the same span of time. In addition, significant coastal subsidence (3 mm/a on average), added by sea-level rise (1.5 mm/a, conservative rate) occurs in the study area, which serves as a negative factor in degrading the coastal plain of Bangladesh in the future, while taking into consideration the weaker sedimentation in the area.  相似文献   

基于遥感和GIS的上海市滩涂湿地资源近期变化分析     

李贵东  周云轩  田波  刘志国  郑宗生 《吉林大学学报(地球科学版)》2008,38(2):319-323

利用多期Landsat-5 TM影像,结合植被分带信息、地物波谱特征和实地调查数据,提取上海地区滩涂湿地分布及其覆盖信息;在ArcGIS软件支持下,综合多期遥感影像解译结果和相应时段的水下地形信息,对上海市滩涂湿地空间分布及其变化进行分析。结果表明,近15年来上海市滩涂围垦量在不断增加;尽管滩涂湿地仍在继续淤涨,但淤涨速度明显减缓,且慢于围垦速度,这导致中高潮滩涂面积不断减少。  相似文献