Self-Organizing Systems in Geography: A Response to Peterman     

Lyle Courtney  Walter G. Hardwick 《The Professional geographer》1995,47(2):218-220

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The relative performance of various cup anemometers in a gusty wind     

Lyle H. Horn 《Theoretical and Applied Climatology》1958,9(2):231-237

Summary Wind data collected during the Great Plains Turbulence Field Experiment of 1953 are used to study the relative performances of various types of cup anemometers subjected to air flow of known gustiness. Scatter diagrams which relate differences in the indicated mean speeds of two anemometers to gustiness are prepared. Although the instruments compared represent a wide range of moments of inertia, no relationship between gustiness and anemometer performance is noted. This result is examined in light of Schrenk's parameter which describes anemometer performance.

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Zusammenfassung Windbeobachtungen, welche während des Great Plains Turbulence Field Program im Jahre 1953 gewonnen wurden, werden zu einem Vergleich verschiedener Typen von Schalenkreuzanemometern in einem Windfeld von bekannter Böigkeit verwendet. Die Ergebnisse werden in Form von Streubildern veranschaulicht, in denen die Geschwindigkeits-unterschiede von verschiedenen Anemometern als Funktion des Böigkeitsgrades aufgetragen sind. Obgleich die verglichenen Anemometer erheblich verschiedene Trägheitsmomente besitzen, ergibt sich keine Abhängigkeit der Anzeigedifferenzen von der Böigkeit des Windes. Dieser Befund wird mit Hilfe des Schrenkschen Parameters näher beleuchtet.

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Résumé Les observations anémométriques effectuées dans le cadre du Great Plains Turbulence Field Program en 1953 sont utilisées ici dans le but de comparer différents types d'anémomètres à cupules placés dans un champ de mouvement de turbulence connue. Les résultats sont donnés sous forme d'essaims de points dans un système de référence: écarts individuels de l'indication et degré de turbulence. Bien que les instruments comparés présentent des moments d'inertie notablement différents, les écarts observés ne dépendent pas de la turbulence du vent. Ce résultat est encore examiné à l'aide du paramètre de Schrenk.

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With 4 Figures  相似文献   

The Huygens scientific data archive: Technical overview     

Olivier Witasse  Lyle Huber  Jean-Pierre Lebreton  David Heather  John Zarnecki  Roland Trautner  Piero Leon Stoppato  Chuck See  Cyril Pennanech  Lisa McFarlane  Bobby Kazeminejad  Brijen Hathi  John Haberman  Francesca Ferri  Lyn Doose  Giacomo Colombatti  Michael Bird  Alessio Aboudan 《Planetary and Space Science》2008,56(5):770-777

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Is irrigated agriculture in the Murray Darling Basin well prepared to deal with reductions in water availability?   总被引：1，自引：0，他引：1  

Yongping WeiJohn Langford  Ian R. WillettSnow Barlow  Clive Lyle 《Global Environmental Change》2011,21(3):906-916

The “Big Dry”, a prolonged dry period in Australia from 1997 to 2009, dried out much of the Murray-Darling Basin (MDB) and resulted in large agricultural losses and degraded river ecosystems. Climate projections are that dry conditions in the MDB are likely to be more regular and severe than ever before, and recent policy initiatives are likely to reduce consumptive water use and redirect water to ecosystem management. This paper aims to develop an understanding of the interactions between water policy and irrigation practices by deriving lessons from drought management in irrigated agriculture of the MDB during the Big Dry, and furthermore, to draw out lessons to enhance the preparedness of irrigated agriculture for a future drier climate and reduced water availability. Reviews of irrigation farmers’ practices, attitudes and capacity to manage during prolonged droughts in the MDB, and the evolution of agricultural water policy in Australia since 1990 were made. It is clear that farmers could be better prepared to deal with a drier climate if their water management practices, e.g. irrigation methods and soil moisture measuring tools are improved, if the impediments to the uncertainty of water allocation and low water availability could be overcome, and if well-targeted research and extension could assist farmers to use water more wisely. It is also clear that Australian water policy could be better prepared in terms of assisting irrigated agriculture to deal with a drier climate. Key areas are reduction of barriers and distortions to water trading, optimizing the environmental water allocation, and seeking mutual benefits between environmental water allocation and irrigated agriculture, improvement of the cost-effectiveness of investments in water supply infrastructure, facilitating carryover and capacity sharing at larger scales, and provision of accurate, accessible and useful water information at different scales. An approach to irrigation practice and water policy is proposed based on past experience and potential opportunities. The approach is a set of linked strategies for more robust agricultural production and a more sustainable environment under a drier climate and reduced water availability.  相似文献   

Headless submarine canyons and fluid flow on the toe of the Cascadia accretionary complex   总被引：1，自引：0，他引：1  

Daniel L. Orange  Brian G. McAdoo  J. Casey Moore  Harold Tobin  Elizabeth Screaton  Hank Chezar  Homa Lee  Mark Reid  & Rick Vail 《Basin Research》1997,9(4):303-312

Headless submarine canyons with steep headwalls and shallowly sloping floors occur on both the second and third landward vergent anticlines on the toe of the Cascadia accretionary complex off central Oregon (45 °N, 125° 30′W). In September 1993, we carried out a series of nine deep tow camera sled runs and nine ALVIN dives to examine the relationship between fluid venting, structure and canyon formation. We studied four canyons on the second and third landward vergent anticlines, as well as the apparently unfailed intercanyon regions along strike. All evidence of fluid expulsion is associated with the canyons; we found no evidence of fluid flow between canyons. Even though all fluid seeps are related to canyons, we did not find seeps in all canyons, and the location of the seeps within the canyons differed. On the landward facing limb of the second landward vergent anticline a robust cold seep community occurs at the canyon’s inflection point. This seep is characterized by chemosynthetic vent clams, tube worms and extensive authigenic carbonate. Fluids for this seep may utilize high-permeability flow paths either parallel to bedding within the second thrust ridge or along the underlying thrust fault before leaking into the overriding section. Two seaward facing canyons on the third anticlinal ridge have vent clam communities near the canyon mouths at approximately the intersection between the anticlinal ridge and the adjacent forearc basin. No seeps were found along strike at the intersection of the slope basin and anticlinal ridge. We infer that the lack of seepage along strike and the presence of seeps in canyons may be related to fluid flow below the forearc basin/slope unconformity (overpressured by the impinging thrust fault to the west?) directed toward canyons at the surface.  相似文献   

A Basin Study of Ground-Water Discharge from Bedrock into Glacial Drift Part I—Definition of Ground-Water System     

Douglas C. Kent  Lyle V. A. Sendlein 《Ground water》1972,10(4):24-34

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Comparison of AnnAGNPS and SWAT model simulation results in USDA‐CEAP agricultural watersheds in south‐central Kansas     

Prem B. Parajuli  Nathan O. Nelson  Lyle D. Frees  Kyle R. Mankin 《水文研究》2009,23(5):748-763

This study was conducted under the USDA‐Conservation Effects Assessment Project (CEAP) in the Cheney Lake watershed in south‐central Kansas. The Cheney Lake watershed has been identified as ‘impaired waters’ under Section 303(d) of the Federal Clean Water Act for sediments and total phosphorus. The USDA‐CEAP seeks to quantify environmental benefits of conservation programmes on water quality by monitoring and modelling. Two of the most widely used USDA watershed‐scale models are Annualized AGricultural Non‐Point Source (AnnAGNPS) and Soil and Water Assessment Tool (SWAT). The objectives of this study were to compare hydrology, sediment, and total phosphorus simulation results from AnnAGNPS and SWAT in separate calibration and validation watersheds. Models were calibrated in Red Rock Creek watershed and validated in Goose Creek watershed, both sub‐watersheds of the Cheney Lake watershed. Forty‐five months (January 1997 to September 2000) of monthly measured flow and water quality data were used to evaluate the two models. Both models generally provided from fair to very good correlation and model efficiency for simulating surface runoff and sediment yield during calibration and validation (correlation coefficient; R², from 0·50 to 0·89, Nash Sutcliffe efficiency index, E, from 0·47 to 0·73, root mean square error, RMSE, from 0·25 to 0·45 m³ s^?1 for flow, from 158 to 312 Mg for sediment yield). Total phosphorus predictions from calibration and validation of SWAT indicated good correlation and model efficiency (R² from 0·60 to 0·70, E from 0·63 to 0·68) while total phosphorus predictions from validation of AnnAGNPS were from unsatisfactory to very good (R² from 0·60 to 0·77, E from ? 2·38 to 0·32). The root mean square error–observations standard deviation ratio (RSR) was estimated as excellent (from 0·08 to 0·25) for the all model simulated parameters during the calibration and validation study. The percentage bias (PBIAS) of the model simulated parameters varied from unsatisfactory to excellent (from 128 to 3). This study determined SWAT to be the most appropriate model for this watershed based on calibration and validation results. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Third-order Middle Miocene-Early Pliocene depositional sequences in the prograding delta complex of the Pannonian Basin     

G. Vakarcs  P.R. Vail  G. Tari  Gy. Pogcss  R.E. Mattick  A. Szab 《Tectonophysics》1994,240(1-4):81-106

Few studies exist in the geologic literature that show the distribution of seismic facies and depositional sequences within a lacustrine basin. The Pannonian Basin of Central Europe offers a unique opportunity to evaluate the influence of the eustatic signal on lacustrine deposition.

Seismic stratigraphie and sedimentological studies indicate that the Middle Miocene-Early Pliocene infill of the transtensional Pannonian Basin was formed by large delta systems. Systematic sequence stratigraphie analysis of 6000 km of reflection seismic data and more than 100 hydrocarbon exploration wells in Hungary allowed the identification of twelve third-order sequence boundaries in the late Neogene sedimentary fill. This number of depositional sequences corresponds to that of the published global eustatic curve for this time period. Furthermore, based on magnetostratigraphic and radiometric data, the ages of these depositional sequences can be tentatively correlated with the global eustatic curve.

The Pannonian Basin became isolated from the world sea at the Sarmatian/Pannonian (11.5 Ma) boundary and formed a large lake. The stratal patterns and sedimentary facies of individual systems tracts within the lacustrine sequences display the same characteristics as marine depositional sequences. The relatively low rate of thermal subsidence and the high rate of sediment supply resulted in a good sequence resolution. Within the third-order sequences higher-order sequences can be recognized with an average duration of about 0.1–0.5 Ma.  相似文献   

Fluxes of metals to a manganese nodule radiochemical,chemical, structural,and mineralogical studies     

Willard S. Moore  Teh-Lung Ku  J. Douglas Macdougall  Virginia Mee Burns  Roger Burns  Jack Dymond  Mitchel W. Lyle  David Z. Piper 《Earth and Planetary Science Letters》1981,52(1):151-171

Fluxes of metals to the top and bottom surfaces of a manganese nodule were determined by combining radiochemical (²³⁰Th,²³¹Pa,²³²Th,²³⁸U,²³⁴U) and detailed chemical data. The top of the nodule had been growing in its collected orientation at 4.7 mm Myr^?1 for at least 0.5 Myr and accreting Mn at 200 μg cm^?2 kyr^?1. The bottom of the nodule had been growing in its collected orientation at about 12 mm Myr^?1 for at least 0.3 Myr and accreting Mn at about 700 μg cm^?2 yr^?1. Although the top of the nodule was enriched in iron relative to the bottom, the nodule had been accreting Fe 50% faster on the bottom.²³²Th was also accumulating more rapidly in the bottom despite a 20-fold enrichment of²³⁰Th on the top.The distribution of alpha-emitting nuclides calculated from detailed radiochemical measurements matched closely the pattern revealed by 109-day exposures of alpha-sensitive film to the nodule. However, the shape and slope of the total alpha profile with depth into the nodule was affected strongly by²²⁶Ra and²²²Rn migrations making the alpha-track technique alone an inadequate method of measuring nodule growth rates.Diffusion of radium in the nodule may have been affected by diagenetic reactions which produce barite, phillipsite and todorokite within 1 mm of the nodule surface; however, our sampling interval was too broad to document the effect. We have not been able to resolve the importance of nodule diagenesis on the gross chemistry of the nodule.  相似文献   

Estimating growth rates of ferromanganese nodules from chemical compositions: implications for nodule formation processes     

Mitchell Lyle 《Geochimica et cosmochimica acta》1982,46(11):2301-2306

Using available information on the accretion rates and the bulk chemical compositions of oceanic ferromanganese nodules, it can be shown that the accumulation rate of manganese is proportional to the square of the accumulation rate of iron. This relationship has been used to derive an equation that predicts nodule growth rates from their chemical compositions. The equation accurately predicts growth rates up to about 50 mm/10⁶ yr, but yields incorrect rates for faster-growing concretions. From this relationship nodules underneath water of high primary productivity grow most rapidly and accumulate transition metals most rapidly; however, nodules from regions of highest primary productivity do not have the highest concentrations of nickel and copper. Reduction of manganese within the sediment column and remobilization of a fraction to the surface sediments adds manganese to nodules without substantially augmenting the supply of other transition elements. The addition of remobilized manganese to the nodule dilutes the concentrations of nickel, copper and iron, even though their rates of accumulation are also high.  相似文献