Correlation of Petrology and Natural Magnetic Polarity in Columbia Plateau Basalts     

R. L. Wilson  N. D. Watkins 《Geophysical Journal International》1967,12(4):405-424

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Temperature fluctuations in the solar photosphere     

P. R. Wilson 《Solar physics》1969,6(3):364-380

The general problem of interpreting granulation data, in particular Edmonds' r.m.s. intensity fluctuation distribution against heliocentric angle , is discussed.A method is developed for investigating a variety of models of inhomogeneous departures from radiative equilibrium using two dimensional solutions of the equation of radiative transfer, and theoretical r.m.s. intensity fluctuation distributions are computed. It is found that only a very narrow range of models yields distributions which exhibit the essential features of Edmonds' distribution (a center-of-disk value of 14 % and a maximum value of 20.5 % at a heliocentric angle of 53°). The feature of these models is a maximum in the temperature fluctuations of about 660 K r.m.s., which represents a temperature difference between hot and cold regions of 2000 K, at a depth of about 250 km below ₅₀₀₀= 0.03. Below this the temperature fluctuations decrease rapidly in the next 70 km.These results are interpreted in terms of convective and radiative transport of energy. Velocities of the order of 8 km/sec are deduced in the essentially convective regime near 320 km, decreasing through 4 km/sec near the temperature fluctuation maximum to negligible values in the radiative region above 200 km.These features are shown to be consistent with modern theoretical and laboratory studies of convection in incompressible fluids. Further, these studies indicate that a second temperature fluctuation should occur at the bottom of a convective layer. For this reason, further photospheric models are studied in which, below the region of small temperature fluctuations near 320 km, the fluctuations increase sharply. For one of these models a theoretical intensity r.m.s. distribution is obtained which closely fits not only the maximum at = 53° in Edmonds' observed distribution but also the initial decrease and smaller minimum near 24°.Of the National Bureau of Standards and the University of Colorado.  相似文献   

The Interference of Higher-Order Statistics of the Concentration Field Produced by Two Point Sources According to a Generalized Fluctuating Plume Model   总被引：1，自引：1，他引：0  

Eugene Yee  Ralph M. Gailis  David J. Wilson 《Boundary-Layer Meteorology》2003,106(2):297-348

The higher-order correlation functions for the concentrationfluctuations arising from a two-point-source configuration have beencalculated analytically within the context of the phenomenology of afluctuating plume model (viz., a meandering plume model that explicitlyincorporates internal fluctuations). Explicit expressions for thesecond-, third-, and fourth-order correlationfunctions between the concentrationfluctuations produced by two point sources are given in terms of the sourceseparation d and the five physically based parameters that define thegeneralized fluctuating plume model: namely, the absolute plume dispersion,_a, which determines the outer plume length scale; the relative plume dispersion, _r, which determines the inner plume length scale; the fluctuation intensity, i_r, in relative coordinates, which determines the internal concentration fluctuation level; the correlation coefficient, r,between the positions of the centroids of the two interfering plumes; and,the correlation coefficient, r^*, between the concentration fluctuationsof the two plumes in relative coordinates, which determines the degree ofinternal mixing of the two scalars. Furthermore, the form of the totalconcentration probability density function arising from the interferenceproduced by two point sources is presented. Predictions for the second-ordercorrelation function, , and for the total concentration probabilitydensity function have been compared with some new experimental data fora two-point-source configuration in grid turbulence generated in awater-channel simulation. These results are in good agreement with the dataand suggest that the analytical model for the second-order correlationfunction and the total concentration probability density function canreproduce many qualitative trends in the interaction of plumes from twosources.  相似文献   

SF₆ as a Conservative Tracer in Saturated Media with High Intragranular Porosity or High Organic Carbon Content     

Ryan D. Wilson  Douglas M. Mackay 《Ground water》1996,34(2):241-249

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Editors’ messages: “Profiles of Eminent Hydrogeologists”     

William E. Wilson 《Hydrogeology Journal》1997,5(2):2-2

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Higher Order Nuptial Fertility in New South Wales, 1996: Context,process, implications     

Murray G. A. Wilson 《The Australian geographer》2001,32(2):181-199

In the face of below replacement and still declining national fertility rates in most Western societies, the proportion of reproductively aged women having a third or higher order birth has particular demographic significance. This paper seeks to complement previous survey-based studies of the socio-economic, behavioural and motivational characteristics of individuals progressing or intending to progress from a second to a third or higher order birth by examining the spatial patterning and ecological context of such births in NSW during 1996 and, in particular, the extent to which such births are especially characteristic of socially disadvantaged regions and localities in the state. The results suggest that while there is a clear, though not overwhelming, tendency towards such a concentration there is an equally clear tendency for older women living in some of the most socially advantaged areas of the metropolitan zone to engage in higher order childbearing, thereby suggesting the operation of multiple causal pathways. In the more disadvantaged areas of the metropolitan zone religious and/or ethnically based pro-natalist value sets also appear to play a significant role. In better-off localities, however, higher order reproduction would seem to reflect the greater choices - and resources - available to women, whether in or out of the labour force. Because ecological analysis cannot provide precise answers to behavioural questions and because only higher order births to women in current relationships have been taken into account in this study, further research, employing a variety of methodologies, operating at a variety of scales and drawing on alternative data sets would seem desirable if such questions are to be more fully elucidated and their policy implications better understood.  相似文献   

Discrete polar motion equations for high frequencies     

Clark R. Wilson  Jianli Chen 《Journal of Geodesy》1996,70(9):581-585

We examine several digital filter methods designed to accurately estimate excitation axis variations from observed polar motion at frequencies exceeding 1 cycle per day. These methods are developed from a discrete time series filter equation originally presented in 1940 by Harold Jeffreys, and subsequently revised over the past two decades. The filters derived here provide improved amplitude accuracy at the highest frequencies now observable in space geodetic polar motion data.  相似文献   

The Spatial Variability of Energy and Carbon Dioxide Fluxes at the Floor of a Deciduous Forest   总被引：6，自引：1，他引：6  

Kell B. Wilson  Tilden P. Meyers 《Boundary-Layer Meteorology》2001,98(3):443-473

Fluxes of carbon dioxide, water and sensible heat were measured using three different eddy covariance systems above the forest floor of a closed deciduous forest (leaf area index approx 6). The primary objective was to examine the representativeness of a single eddy covariance system in estimating soil respiration for time scales ranging from one-half hour to more than one week. Experiments were conducted in which the eddy covariance sensors were in one of three configurations: i) collocated, ii) separated horizontally or iii) separated vertically. A measure of the variation between the three systems (CV',related to the coefficient of variation) for half-hour carbon dioxide fluxes was 0.14 (collocated systems), 0.34 (vertically separated systems at 1, 2 and 4 m above the surface), and 0.57 (systems horizontally separated by 30 m). A similar variation was found for other scalar fluxes (sensible and latent heat). Variability between systems decreased as the number of half-hour sampling periods used to obtain mean fluxes was increased. After forty-eight hours (means from ninety-six half-hour samples), CV' values for carbon dioxide fluxes were 0.07, 0.09 and 0.16 in the collocated, vertically separated and horizontally separated experiments, respectively. The time dependence of variability has implications on the appropriateness of using short-term measurements in modelling validation studies. There are also implications concerning the appropriate number of half-hour samples necessary to obtain reliable causal relationships between flux data and environmental parameters. Based on the longer-term measurements, we also discuss the representativeness of a single eddy covariance system in long-term monitoring of soil respiration and evaporation beneath forest canopies using the eddy covariance method.  相似文献   

Turbulence statistics of a Kelvin–Helmholtz billow event observed in the night-time boundary layer during the Cooperative Atmosphere–Surface Exchange Study field program     

William Blumen  Robert Banta  Sean P. Burns  David C. Fritts  Rob Newsom  Gregory S. Poulos  Jielun Sun   《Dynamics of Atmospheres and Oceans》2001,34(2-4)

An apparent shear flow instability occurred in the stably stratified night-time boundary layer on 6 October 1999 over the Cooperative Atmosphere–Surface Exchange Study (CASES-99) site in southeast Kansas. This instability promoted a train of billows which appeared to be in different stages of evolution. Data were collected by sonic anemometers and a high-frequency thermocouple array distributed on a 60 m tower at the site, and a high resolution Doppler lidar (HRDL), situated close to the tower. Data from these instruments were used to analyze the characteristics of the instability and the billow event. The instability occurred in a layer characterized by a minimum Richardson number Ri0.13, and where an inflection in the background wind profile was also documented. The billows, which translated over the site for approximately 30 min, were approximately L320 m in length and, after billow evolution they were contained in a layer depth H30 m. Their maximum amplitude, determined by HRDL data, occurred at a height of 56 m. Billow overturns, responsible for mixing of heat and momentum, and high-frequency intermittent turbulence produce kurtosis values above the Gaussian value of 3, particularly in the lower part of the active layer.  相似文献   

Stratigraphic and structural expression of the lateral growth of thrust fault-propagation folds: results and implications from kinematic modelling     

Kate A. Cooper  Stuart Hardy  Rob Gawthorpe 《Basin Research》2003,15(2):165-182

In order to better understand the development of thrust fault‐related folds, a 3D forward numerical model has been developed to investigate the effects that lateral slip distribution and propagation rate have on the fold geometry of pre‐ and syn‐tectonic strata. We consider a fault‐propagation fold in which the fault propagates upwards from a basal decollement and along‐strike normal to transport direction. Over a 1 Ma runtime, the fault reaches a maximum length of 10 km and accumulates a maximum displacement of 1 km. Deformation ahead of the propagating fault tip is modelled using trishear kinematics while backlimb deformation is modelled using kink‐band migration. The applicability of two different lateral slip distributions, namely linear‐taper and block‐taper, are firstly tested using a constant lateral propagation rate. A block‐taper slip distribution replicates the geometry of natural fold‐thrusts better and is then used to test the sensitivity of thrust‐fold morphology to varied propagation rates in a set of fault‐propagation folds that have identical final displacement to length (D_max/L_max) ratios. Two stratigraphic settings are considered: a model in which background sedimentation rates are high and no topography develops, and a model in which a topographic high develops above the growing fold and local erosion, transport and deposition occur. If the lateral propagation rate is rapid (or geologically instantaneous), the fault tips quickly become pinned as the fault reaches its maximum lateral extent (10 km), after which displacement accumulates. In both stratigraphic settings, this leads to strike‐parallel rotation of the syn‐tectonic strata near the fault tips; high sedimentation rates relative to rates of uplift result in along‐strike thinning over the structural high, while low sedimentation rates result in pinchout against it. In contrast, slower lateral propagation rates (i.e. up to one order of magnitude greater than slip rate) lead to the development of along‐strike growth triangles when sedimentation rates are high, whereas when sedimentation rates are low, offflap geometries result. Overall we find that the most rapid lateral propagation rates produce the most realistic geometries. In both settings, time‐equivalent units display both nongrowth and growth stratal geometries along‐strike and the transition from growth to nongrowth has the potential to delineate the time of fault/fold growth at a given location. This work highlights the importance of lateral fault‐propagation and fault tip pinning on fault and fold growth in three dimensions and the complex syn‐tectonic geometries that can result.  相似文献