The chemistry of soil constituents: D.J. Greenland and M.H. Hayes. Wiley,New York,N.Y., 1978, 469 pp., £ 26     

Barbara Grabowska-Olszewska 《Sedimentary Geology》1981,28(1):77-78

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Amethod of estimating leaf temperatures in a plant community     

Dr. Barbara van Meurs 《Theoretical and Applied Climatology》1976,24(1-2):77-83

Summary A method was devised for using profiles of directional long-wave radiation to estimate plant radiating temperatures at any height in a crop. Limited testing of the method was carried out using tubular net radiometers which had one hemisphere covered by a radiation shield equipped with a temperature sensor.The results indicated that, in the absence of solar radiation, profiles of effective radiating temperature in a crop could be obtained to an accuracy of between 0.2 and 0.3°C at any level while day time values were of the order of 0.3 to 0.4°C.

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Eine Methode zur Abschätzung der Blattemperatur in einer Pflanzengemeinschaft

Zusammenfassung Es wurde eine Methode entwickelt, die es erlaubt, die Strahlungstemperatur von Pflanzen in beliebiger Höhe innerhalb eines Bestandes aus Profilen der langwelligen Strahlungsbilanz abzuschätzen. Eine beschränkte Zahl von Versuchen wurde ausgeführt, bei denen zylinderförmige Strahlungsbilanzmesser verwendet wurden, deren eine Hemisphäre durch einen Strahlungsschirm verdeckt war, an dem ein Temperaturmeßgerät angebracht war. Die Resultate zeigen, daß bei fehlender Sonnenstrahlung Profile der effektiven Strahlungs-temperatur in beliebiger Höhe innerhalb eines Bestandes bis zu einer Genauigkeit von 0.2 bis 0.3°C gemessen werden können. Untertags wurden Genauigkeiten von 0.3 bis 0.4° erzielt.

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With 2 Figures  相似文献   

The mass and moment of inertia of the Earth     

Barbara Romanowicz  Kurt Lambeck 《Physics of the Earth and Planetary Interiors》1977,15(1):P1-P4

Recent revisions of geodetic and astronomical constants by the International Association of Geodesy and the International Astronomical Union lead to improved values for the earth's mass and moment of inertia. Corrections to be applied to these values before they are used as constraints in the inversion of seismic data are discussed.  相似文献   

A Late‐glacial chironomid record from Hawes Water,northwest England     

Alan Bedford  Richard. T. Jones  Barbara Lang  Stephen Brooks  Jim D. Marshall 《第四纪科学杂志》2004,19(3):281-290

This paper presents the results of a high‐resolution Late‐glacial chironomid stratigraphy from Hawes Water, a small carbonate lake in northern Lancashire. The samples were from a core taken from the terrestrialised margin of the present lake, which represents an intermediate depth between the true littoral and the profundal. The chironomid assemblage showed a high degree of sensitivity to both broad‐scale and short‐term temperature changes. Comparison with an existing proxy temperature record (δ¹⁸O) for the site confirmed the presence of four temperature inversions within the Late‐glacial Interstadial. A mean July air temperature inference model, derived from acid, soft‐water lakes in Norway and Svalbard, was applied to the data. Despite the absence of carbonate lakes within the Norwegian training set, there was a close similarity between trends in estimated July air temperature and the δ¹⁸O trace, with a particularly strong correspondence in the periods of clay deposition. This suggests that this model is highly robust. The inferred maximum Interstadial temperature was 13.4°C, dropping initially to 7.5°C in the Loch Lomond Stadial. Temperatures reach a maximum of nearly 10°C in this period, cool for a short period before rising rapidly to 13.2°C at the start of the Holocene. These temperatures are similar to but slightly higher than those estimated for Whitrig Bog, southeast Scotland, and lower than those inferred from coleopteran‐based models for sites in South Wales. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

HST observations of azimuthal asymmetry in Saturn's rings     

Richard G. French  Heikki Salo  Luke Dones 《Icarus》2007,189(2):493-522

From 378 Hubble Space Telescope WFPC2 images obtained between 1996-2004, we have measured the detailed nature of azimuthal brightness variations in Saturn's rings. The extensive geometric coverage, high spatial resolution (), and photometric precision of the UBVRI images have enabled us to determine the dependence of the asymmetry amplitude and longitude of minimum brightness on orbital radius, ring elevation, wavelength, solar phase angle, and solar longitude. We explore a suite of dynamical models of self-gravity wakes for two particle size distributions: a single size and a power law distribution spanning a decade in particle radius. From these N-body simulations, we calculate the resultant wake-driven brightness asymmetry for any given illumination and viewing geometry. The models reproduce many of the observed properties of the asymmetry, including the shape and location of the brightness minimum and the trends with ring elevation and solar longitude. They also account for the “tilt effect” in the A and B rings: the change in mean ring brightness with effective ring opening angle, |Beff|. The predicted asymmetry depends sensitively on dynamical ring particle properties such as the coefficient of restitution and internal mass density, and relatively weakly on photometric parameters such as albedo and scattering phase function. The asymmetry is strongest in the A ring, reaching a maximum amplitude A∼25% near a=128,000 km. Here, the observations are well-matched by an internal particle density near 450 kg m⁻³ and a narrow particle size distribution. The B ring shows significant asymmetry (∼5%) in regions of relatively low optical depth (τ∼0.7). In the middle and outer B ring, where τ?1, the asymmetry is much weaker (∼1%), and in the C ring, A<0.5%. The asymmetry diminishes near opposition and at shorter wavelengths, where the albedo of the ring particles is lower and multiple-scattering effects are diminished. The asymmetry amplitude varies strongly with ring elevation angle, reaching a peak near |Beff|=10° in the A ring and at |Beff|=15-20° in the B ring. These trends provide an estimate of the thickness of the self-gravity wakes responsible for the asymmetry. Local radial variations in the amplitude of the asymmetry within both the A and B rings are probably caused by regional differences in the particle size distribution.  相似文献   

Saturn eddy momentum fluxes and convection: First estimates from Cassini images     

Anthony D. Del Genio  John M. Barbara  Andrew P. Ingersoll  Ashwin R. Vasavada  Carolyn C. Porco 《Icarus》2007,189(2):479-492

We apply an automated cloud feature tracking algorithm to estimate eddy momentum fluxes in Saturn's southern hemisphere from Cassini Imaging Science Subsystem near-infrared continuum image sequences. Voyager Saturn manually tracked images had suggested no conversion of eddy to mean flow kinetic energy, but this was based on a small sample of <1000 wind vectors. The automated procedure we use for the Cassini data produces an order of magnitude more usable wind vectors with relatively unbiased sampling. Automated tracking is successful in and around the westward jet latitudes on Saturn but not in the vicinity of most eastward jets, where the linearity and non-discrete nature of cloud features produces ambiguous results. For the regions we are able to track, we find peak eddy fluxes and a clear positive correlation between eddy momentum fluxes and meridional shear of the mean zonal wind, implying that eddies supply momentum to eastward jets and remove momentum from westward jets at a rate . The behavior we observe is similar to that seen on Jupiter, though with smaller eddy-mean kinetic energy conversion rates per unit mass of atmosphere (). We also use the appearance and rapid evolution of small bright features at continuum wavelengths, in combination with evidence from weak methane band images where possible, to diagnose the occurrence of moist convective storms on Saturn. Areal expansion rates imply updraft speeds of over the convective anvil cloud area. As on Jupiter, convection preferentially occurs in cyclonic shear regions on Saturn, but unlike Jupiter, convection is also observed in eastward jet regions. With one possible exception, the large eddy fluxes seen in the cyclonic shear latitudes do not seem to be associated with convective events.  相似文献   

Localization and characterization of an active fault in an urbanized area in central Guatemala by means of geoelectrical imaging     

Barbara Suski  Gilles Brocard  Christine Authemayou  Beatriz Consenza Muralles  Christian Teyssier  Klaus Holliger 《Tectonophysics》2010,480(1-4):88-98

The Polochic and Motagua faults define the active plate boundary between the North American and Caribbean plates in central Guatemala. A splay of the Polochic Fault traverses the rapidly growing city of San Miguel Uspantán that is periodically affected by destructive earthquakes. This fault splay was located using a 2D electrical resistivity tomography (ERT) survey that also characterized the fault damage zone and evaluated the thickness and nature of recent deposits upon which most of the city is built. ERT images show the fault as a ~50 m wide, near-vertical low-resistivity anomaly, bounded within a few meters by high resistivity anomalies. Forward modeling reproduces the key aspects of the observed electrical resistivity data with remarkable fidelity thus defining the overall location, geometry, and internal structure of the fault zone as well as the affected lithologies. Our results indicate that the city is constructed on a ~20 m thick surficial layer consisting of poorly consolidated, highly porous, water-logged pumice. This soft layer is likely to amplify seismic waves and to liquefy upon moderate to strong ground shaking. The electrical conductivity as well as the major element chemistry of the groundwater provides evidence to suggest that the local aquifer might, at least in part, be fed by water rising along the fault. Therefore, the potential threat posed by this fault splay may not be limited to its seismic activity per se, but could be compounded its potential propensity to enhance seismic site effects by injecting water into the soft surficial sediments. The results of this study provide the basis for a rigorous analysis of seismic hazard and sustainable development of San Miguel Uspantán and illustrate the potential of ERT surveying for paleoseismic studies.  相似文献   

Solar shield: forecasting and mitigating space weather effects on high-voltage power transmission systems     

Antti Pulkkinen  Michael Hesse  Shahid Habib  Luke Van der Zel  Ben Damsky  Fritz Policelli  David Fugate  William Jacobs  Elizabeth Creamer 《Natural Hazards》2010,53(2):333-345

In this paper, central elements of the Solar Shield project, launched to design and establish an experimental system capable of forecasting the space weather effects on high-voltage power transmission system, are described. It will be shown how Sun–Earth system data and models hosted at the Community Coordinated Modeling Center (CCMC) are used to generate two-level magnetohydrodynamics-based forecasts providing 1–2 day and 30–60 min lead-times. The Electric Power Research Institute (EPRI) represents the end-user, the power transmission industry, in the project. EPRI integrates the forecast products to an online display tool providing information about space weather conditions to the member power utilities. EPRI also evaluates the economic impacts of severe storms on power transmission systems. The economic analysis will quantify the economic value of the generated forecasting system. The first version of the two-level forecasting system is currently running in real-time at CCMC. An initial analysis of the system’s capabilities has been completed, and further analysis is being carried out to optimize the performance of the system. Although the initial results are encouraging, definite conclusions about system’s performance can be given only after more extensive analysis, and implementation of an automatic evaluation process using forecasted and observed geomagnetically induced currents from different nodes of the North American power transmission system. The final output of the Solar Shield will be a recommendation for an optimal forecasting system that may be transitioned into space weather operations.  相似文献   

Investigating the igneous petrogenesis of Martian volcanic rocks using augite quantitative textural analysis of the Yamato nakhlites     

Sammy Griffin  Arya Udry  Luke Daly  Lucy Victoria Forman  Martin R. Lee  Benjamin E. Cohen 《Meteoritics & planetary science》2023,58(1):63-84

To better understand volcanism on planetary bodies other than the Earth, the quantification of physical processes is needed. Here, the petrogenesis of the achondrite Martian Yamato (Y) nakhlites (Y 000593, Y 000749, and Y 000802) is reinvestigated via quantitative analysis of augite (high-Ca clinopyroxene) phenocrysts: crystal size distribution (CSD), spatial distribution patterns (SDP), and electron backscatter diffraction (EBSD). Results from CSD and EBSD quantitative data sets show augite to have continuous uninterrupted growth resulting in calculated minimum magma chamber residence times of either 88–117 ± 6 yr or 9–12 yr. All samples exhibit low-intensity S-LS type crystallographic preferred orientation. Directional strain is observed across all samples with intracrystalline misorientation patterns indicative of (100)[001]:(001)[100] (Y 000593 and Y 000802) and {110}<001>or {110}¹/₂<110> (Y 000749) slip systems. SDP results indicate phenocryst-bearing crystal-clustered rock signatures. Combined findings from this work show that the Yamato nakhlites formed on Mars as individual low-viscosity lava flows or sills. This study shows that through combining these different quantitative techniques over multiple samples, one can more effectively compare and interpret resulting data to gain a more robust, geologically contextualized petrogenetic understanding of the rock suite being studied. The techniques used in this study should be equally applicable to igneous achondrites from other parent bodies.  相似文献   

Mesh size effects on mesozooplankton community structure in a semi‐enclosed coastal area and surrounding sea (South Adriatic Sea)     

Marijana Miloslavić  Davor Lučić  Barbara Gangai  Ivona Onofri 《Marine Ecology》2014,35(4):445-455

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