Pesticides as tracers of sediment transport through Monterey Canyon     

C. Paull  H. Greene  W. Ussler  P. Mitts 《Geo-Marine Letters》2002,22(3):121-126

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New insights on the binary Asteroid 121 Hermione     

P. Descamps  F. Marchis  J. Durech  A.W. Harris  J. Berthier  A. Peyrot  J. Greene  M. Assafin  J.I.B. Camargo  F. Vachier  K.M. Ivarsen  M.C. Nysewander  J.B. Haislip  F. Colas  L. Bernasconi  P. Baudouin  S. Sposetti 《Icarus》2009,203(1):88-101

We report on the results of a 6-month photometric study of the main-belt binary C-type Asteroid 121 Hermione, performed during its 2007 opposition. We took advantage of the rare observational opportunity afforded by one of the annual equinoxes of Hermione occurring close to its opposition in June 2007. The equinox provides an edge-on aspect for an Earth-based observer, which is well suited to a thorough study of Hermione’s physical characteristics. The catalog of observations carried out with small telescopes is presented in this work, together with new adaptive optics (AO) imaging obtained between 2005 and 2008 with the Yepun 8-m VLT telescope and the 10-m Keck telescope. The most striking result is confirmation that Hermione is a bifurcated and elongated body, as suggested by Marchis, et al. [Marchis, F., Hestroffer, D., Descamps, P., Berthier, J., Laver, C., de Pater, I., 2005. Icarus 178, 450-464]. A new effective diameter of 187 ± 6 km was calculated from the combination of AO, photometric and thermal observations. The new diameter is some 10% smaller than the hitherto accepted radiometric diameter based on IRAS data. The reason for the discrepancy is that IRAS viewed the system almost pole-on. New thermal observations with the Spitzer Space Telescope agree with the diameter derived from AO and lightcurve observations. On the basis of the new AO astrometric observations of the small 32-km diameter satellite we have refined the orbit solution and derived a new value of the bulk density of Hermione of 1.4 + 0.5/−0.2 g cm⁻³. We infer a macroscopic porosity of ∼33 + 5/−20%.  相似文献   

Determining the Oxygen Isotope Composition of Evapotranspiration Using Eddy Covariance     

T. J. Griffis  S. D. Sargent  X. Lee  J. M. Baker  J. Greene  M. Erickson  X. Zhang  K. Billmark  N. Schultz  W. Xiao  N. Hu 《Boundary-Layer Meteorology》2010,134(2):307-325

Impacts of different terrain configurations on the general behaviour of idealised katabatic flows are investigated in a numerical model study. Various simplified terrain models are applied to unveil modifications of the dynamics of nocturnal cold drainage of air as a result of predefined topographical structures. The generated idealised terrain models encompass all major topographical elements of an area in the tropical eastern Andes of southern Ecuador and northern Peru, and the adjacent Amazon. The idealised simulations corroborate that (i) katabatic flows develop over topographical elements (slopes and valleys), that (ii) confluence of katabatic flows in a lowland basin with a concave terrainline occur, and (iii) a complex drainage flow system regime directed into such a basin can sustain the confluence despite varying slope angles and slope distances.  相似文献   

Interpretation of Prematurely Terminated Air-Pressurized Slug Tests     

Allen M. Shapiro  Earl A. Greene 《Ground water》1995,33(4):539-546

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Tracing Recharge from Sinking Streams over Spatial Dimensions of Kilometers in a Karst Aquifer   总被引：2，自引：0，他引：2  

Earl A. Greene 《Ground water》1997,35(5):898-904

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A scale-invariant approach to flood-frequency analysis     

D. L. Turcotte  L. Greene 《Stochastic Hydrology and Hydraulics》1993,7(1):33-40

In order to study historical flood-frequency records we plot the log of the number of floods on a river per unit time in which the peak discharge exceeds a specified value against the log of that value. For ten benchmark stations we find good correlations with scale-invariant (fractal) statistics. We suggest that the underlying physical processes associated with the generation of floods are sufficiently scale invariant over time scales from one to one hundred years that they provide a rational basis for the application of scale-invariant statistics. Our results fall within the range of flood-frequency estimates made by other statistical techniques. We propose that the ratio of the ten-year peak discharge to the one-year peak discharge is a quantitative measure of flood potential. With scale invariance is also the ratio of the one-hundred year flood to the ten-year flood. We find that the values of for ten stations on rivers throughout the country range from 2.04 to 8.11 and find strong regional variations that can be correlated in terms of climate. Our results are consistent with the observed fractal statistics in sedimentary sections. We have also carried out R/S analyses for the ten stations and have obtained values of the Hurst exponent. We find that the Hurst exponent cannot be used for flood-frequency forecasting.  相似文献   

A scale-invariant approach to flood-frequency analysis     

D. L. Turcotte  L. Greene 《Stochastic Environmental Research and Risk Assessment (SERRA)》1993,7(1):33-40

In order to study historical flood-frequency records we plot the log of the number of floods on a river per unit time in which the peak discharge exceeds a specified value against the log of that value. For ten benchmark stations we find good correlations with scale-invariant (fractal) statistics. We suggest that the underlying physical processes associated with the generation of floods are sufficiently scale invariant over time scales from one to one hundred years that they provide a rational basis for the application of scale-invariant statistics. Our results fall within the range of flood-frequency estimates made by other statistical techniques. We propose that the ratio of the ten-year peak discharge to the one-year peak discharge is a quantitative measure of flood potential. With scale invariance is also the ratio of the one-hundred year flood to the ten-year flood. We find that the values of for ten stations on rivers throughout the country range from 2.04 to 8.11 and find strong regional variations that can be correlated in terms of climate. Our results are consistent with the observed fractal statistics in sedimentary sections. We have also carried out R/S analyses for the ten stations and have obtained values of the Hurst exponent. We find that the Hurst exponent cannot be used for flood-frequency forecasting.  相似文献   

The upper Jovian atmosphere aerosol content determined from a satellite eclipse observation     

Dale W. Smith  Thomas F. Greene  Richard W. Shorthill 《Icarus》1977,30(4):697-729

The Galilean satellite eclipse technique for measuring the aerosol distribution in the upper Jovian atmosphere is described and applied using 30 color observations of the 13 May 1972 eclipse of Ganymede obtained with the 5-m Hale telescope. This event probes the South Temperate Zone. The observed aerosol lies above the visible cloud tops, is very tenuous and varies with altitude, increasing rapidly with downward passage through the tropopause. The aerosol extinction coefficient, κ_a (λ1.05 μm), is ～1.1 × 10^?9 cm^?1 in the lower stratosphere and ～1.1 × 10^?8 cm^?1 at the tropopause. The 1σ uncertainty in these values does not exceed 50% The observations require some aerosol above the tropopause but do not clearly determine its structure. The present analysis emphasizes an extended haze distribution, but the alternate possibility is not excluded that the stratospheric aerosol resides in a thin layer. The aerosol extinction increases with decreasing wavelength and indicates the particle radius to be ?0.2 μm. Larger radii are impossible. These overall results confirm Axel's (1972) suggestion of a small quantity of dust above the Jovian cloud tops and the optical depths are consistent with those required to explain the low uv albedo.  相似文献   

吐哈盆地煤成烃研究新进展   总被引：7，自引：0，他引：7  

程克明  熊英  J M Moldowan  J Greene Todd 《沉积学报》2002,20(3):456-461

运用生物标记物及碳同位素等地化参数对吐鲁番 -哈密盆地的原油及其源岩进行了油源对比 |结果将该区原油分为三类 :第一类原油 |根据生标特征分析其具有显著的淡水环境、藻含量低、细菌影响大、C₂₉甾烷含量高、C₃₀4_α- 甲基甾烷低、C₂₄ 四环烷和C₁₉三环烷含量高和碳同位素偏重 (δ13C为 - 25‰~ - 27‰ )的特点 |初步对比结果 |本区西山窑组的煤是该类原油的主要源岩;第二类原油 |富含藻类物质(C₂₇甾烷与C₃₀4_α-甲基甾烷含量较高 ) |该类原油可能来自侏罗系的富藻湖相泥岩;第三类原油 |全油碳同位素δ13C为 - 30‰~ - 32‰ |这类原油的生标反映出其源岩相的特征为缺氧、咸水、中等含藻的湖相沉积 (高含量的伽玛蜡烷和 β_-胡萝卜烷|C₃₅/C₃₄藿烷比值大等 )。  相似文献   

北大别黄土岭麻粒岩锆石U—Pb离子探针定年   总被引：28，自引：6，他引：28  

吴元保  陈道公  夏群科  Etienne DELOULE  程昊 《岩石学报》2002,18(3):378-382

阴极发光显微结构分析表明 ,北大别黄土岭麻粒岩中存在三种类型的锆石 :原岩锆石、麻粒岩相锆石和残留锆石。对它们分别进行离子探针定年 ,得到黄土岭麻粒岩的原岩年龄约为 2 70 0 Ma、麻粒岩相变质事件的年龄为 2 0 5 2± 10 0 Ma、残留锆石的年龄为约 3.4 Ga。以上研究表明黄土岭麻粒岩为残存的扬子板块的结晶基底 ,而约 3.4 Ga残留锆石的发现 ,则首次证明大别山地区存在古太古代的陆壳物质  相似文献