The effect of uncertainty in aerodynamic resistance on evaporation estimates from the combination model   总被引：1，自引：0，他引：1  

W. G. Bailey  J. A. Davies 《Boundary-Layer Meteorology》1981,20(2):187-199

Evaporation estimates from a soybean crop calculated from the combination model are insensitive to aerodynamic resistance. The insensitivity arises from a strong link between evaporation and the vapour pressure deficit of the air and bulk stomatal resistance. The sensitivity of aerodynamic resistance to errors in surface roughness and zero-plane displacement is considered. The resistance is found to be more sensitive to errors in surface roughness than to errors in zero-plane displacement. However, large errors in these have little effect on calculated evaporation. Both surface roughness and zero-plane displacement are empirically related to crop height and leaf area index. Errors incurred by ignoring bluff-body effects and atmospheric stability are small in estimating both resistance and evaporation. Evaporation can be calculated adequately from empirical estimates of surface roughness and zero-plane displacement and single-level measurements of windspeed.  相似文献   

Eburru volcano: A re-appraisal of the previous sample population     

D. K. Bailey  S. D. Weaver  D. S. Sutherland 《Contributions to Mineralogy and Petrology》1975,50(1):47-48

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A method of analyzing polymodal distributions in orientation data     

A. I. Bailey 《Mathematical Geosciences》1975,7(4):285-293

A method of cluster analysis for orientation data is described. The method enables vector statistics to be applied to polymodal distributions. Similar results to those found by modal analysis are obtained.  相似文献   

An analogue model study of electromagnetic induction in the eastern coastal region of North America     

H.W. Dosso  W. Nienaber  J.A. Wright  J.P. Greenhouse  R.C. Bailey 《Physics of the Earth and Planetary Interiors》1980,23(1):13-30

The behavior of electric and magnetic field variations over the eastern coastal region of North America is studied using a scaled laboratory electromagnetic analogue model. The model source frequency used simulates a period of 1 h in the geophysical scale. The results indicate that deflection and conductive channelling of induced electric current is important for both the E-polarization (northeast-southwest direction of the electric field of the source) and the H-polarization (northwest-southeast) of the source field. In the model, conductive channelling occurs through the Strait of Belle Isle, Cabot Strait, and in the St. Lawrence River. Current deflection is particularly prevalent around the southeast coast of Newfoundland for both E- and H-polarization, and around the northeast coastline of Nova Scotia for E-polarization. The model results also show current deflection by cape and bay coastal features, as well as by ocean depth contours.A comparison of model measurements for the cases of a uniform source field and a line current source indicate that the nature of the source field has a measurable but surprisingly small effect on the vertical to horizontal magnetic field ratio for both E- and H-polarizations, and negligible effect on the magnetotelluric ratio for coastal regions.The model fields in coastal regions were found to be strongly influenced by induced currents, deflected and channelled by the coastline and ocean bathymetry, and were dependent on the nature and particularly the polarization of the source field. Thus, along the complex coastline of eastern North America, a wide range of electric and magnetic field values should be expected. In some regions the coast effect, measured by the vertical to horizontal magnetic field ratio at the coast, could be expected to be extremely small or absent, while in other regions the ratio could approach a value as large as unity for variations of 1 h period.  相似文献   

Saldanha Bay,South Africa I: the use of ocean colour remote sensing to assess phytoplankton biomass     

ME Smith  GC Pitcher 《African Journal of Marine Science》2015,37(4):503-512

The efficacy of ocean colour remote sensing in assessing the variability of phytoplankton biomass within Saldanha Bay is examined. Satellite estimates of chlorophyll a (Chl a) were obtained using the maximum peak-height (MPH) algorithm on full-resolution (300?m) data from the Medium Resolution Imaging Spectrometer (MERIS). Subsurface Chl a maxima often occur within Saldanha Bay below the mean detection depth of the satellite (1.5?m) during periods of thermal stratification. Consequently, the MPH product was poorly correlated to in situ data from 4?m depth (r² and average relative percentage difference [RPD] of 0.094 and 53% respectively); however, the coefficient of determination was much improved if limited to in situ data collected under conditions of mixing (r² and RPD of 0.869 and 89%, respectively). Composites of monthly MPH Chl a data reveal mean concentrations consistent with in situ seasonal trends of phytoplankton biomass, confirming the capability of the MPH algorithm to qualitatively resolve surface Chl a distribution within the bay.  相似文献   

Radiation hydrodynamic simulation of a photoionised plasma experiment at the Z facility     

I. M. Hall  T. Durmaz  R. C. Mancini  J. E. Bailey  G. A. Rochau 《Astrophysics and Space Science》2011,336(1):189-194

New, high spectral resolution X-ray observations from astrophysical photoionised plasmas have been recorded in recent years by the Chandra and XMM-Newton orbiting telescopes. These observations provide a wealth of detailed information and have motivated new efforts at developing a detailed understanding of the atomic kinetics and radiation physics of photoionised plasmas. The Z facility at Sandia National Laboratories is a powerful source of X-rays that enables us to produce and study photoionised plasmas in the laboratory under well characterised conditions. We discuss a series of radiation-hydrodynamic simulations to help understand the X-ray environment, plasma hydrodynamics and atomic kinetics in experiments where a collapsing wire array at Z is used as an ionising source of radiation to create a photoionised plasma. The numerical simulations are used to investigate the role that the key experimental parameters have on the photoionised plasma characteristics.  相似文献   

Yardangs in terrestrial ignimbrites: Synergistic remote and field observations on Earth with applications to Mars   总被引：1，自引：0，他引：1  

S.L. de Silva  J.E. Bailey 《Planetary and Space Science》2010,58(4):459-482

The conditions of formation and the form of yardangs in ignimbrites in the Central Andes of Chile, Bolivia, and Argentina may be the most convincing terrestrial analog to the processes and lithology that produce the extensive yardangs of the Medusae Fossae Formation (MFF) of Mars. Through remote and field study of yardang morphologies in the Central Andes we highlight the role that variable material properties of the host lithology plays in their final form. Here, ignimbrites typically show two main facies: an indurated and jointed facies, and a weakly to poorly indurated, ash- and pumice-rich facies. Both facies are vertically arranged in large (erupted volume >100's of km³) ignimbrites resulting in a resistant capping layer, while smaller (10's of km³) ignimbrites are made predominantly of the weakly indurated facies. The two facies have quite different mechanical properties; the indurated facies behaves as strong rock, fails by block collapse and supports steep/vertical cliffs, while the non-indurated facies is more easily eroded and forms gentle slopes and manifests as more subdued erosional forms. In response to aeolian action, the presence of an upper indurated facies results in large, elongate, high aspect ratio (1:20-1:40) megayardangs that form tall (100 m), thin ridges with steep to vertical walls. These are built on a broad apron of the weakly indurated facies with abundant fallen blocks from the upper indurated facies. These terrestrial megayardangs appear to be analogous to megayardangs with associated block fields seen on Mars. Smaller-volume, weakly indurated ignimbrites are sculpted into smaller, stubbier forms with aspect ratios of 1:5-1:10 and heights rarely exceeding 10 m. Excavation of a windward basal moat suggests an erosional progression like that seen in incipient yardangs on Mars. Excavation rates of 0.007-0.003 cm/year are calculated for the weakly indurated ignimbrites. While a persistent strong unidirectional wind is the dominant parameter controlling yardang formation and orientation, a role for flow separation and vorticity is also suggested by our observations at both yardang types. While the indurated facies is commonly pervasively jointed, jointing is of secondary importance in controlling yardang orientation. Serrated margins, a common feature on Mars, result from oblique intersections of jointing with yardang flanks or scarps of ignimbrite. The processes of yardang formation we describe from ignimbrites from the Central Andes are not necessarily specific to ignimbrites, but do connote that degree and distribution of induration is a major control in yardang formation and this has implications for the lithology of the MFF on Mars.  相似文献   

A comparative dental metrical and morphological analysis of a Middle Pleistocene hominin maxilla from Chaoxian (Chaohu), China     

Shara E. Bailey  Wu Liu 《Quaternary International》2010,211(1-2):14-23

A hominin maxilla, discovered in 1983 in Chaoxian County, Anhui Province, eastern China represents one of several Asian hominins dating to the late Middle Pleistocene. Although the maxilla and associated occipital have been described, no detailed study of the dentition has been made. This study provides metrical and morphological information on the Chaoxian dentition and places it into a larger Middle to Late Pleistocene context. Implications for the taxonomy of Middle Pleistocene hominins are discussed.  相似文献   

Evaluating sulfur dynamics during storm events for three watersheds in the northeastern USA: a combined hydrological,chemical and isotopic approach     

Myron J. Mitchell  Scott W. Bailey  James B. Shanley  Bernhard Mayer 《水文研究》2008,22(20):4023-4034

Concerns related to climate change have resulted in an increasing interest in the importance of hydrological events such as droughts in affecting biogeochemical responses of watersheds. The effects of an unusually dry summer in 2002 had a marked impact on the biogeochemistry of three watersheds in the north‐eastern USA. Chemical, isotopic and hydrological responses with particular emphasis on S dynamics were evaluated for Archer Creek (New York), Sleepers River (Vermont) and Cone Pond (New Hampshire) watersheds. From 1 August to 14 September 2002, all three watersheds had very low precipitation (48 to 69 mm) resulting in either very low or no discharge (mean 0·015, 0·15 and 0·000 mm day^?1 for Archer Creek, Sleepers River and Cone Pond, respectively). From 15 September to 31 October 2002, there was a substantial increase in precipitation totals (212, 246 and 198 mm, respectively) with increased discharge. Archer Creek was characterized by a large range of SO₄^2? concentrations (152 to 389 µeq L^?1, mean = 273 µeq L^?1) and also exhibited the greatest range in δ³⁴S values of SO₄^2? (?1·4 to 8·8 ‰ ). Sleepers River's SO₄^2? concentrations ranged from 136 to 243 µeq L^?1 (mean = 167 µeq L^?1) and δ³⁴S values of SO₄^2? ranged from 4·0 to 9·0 ‰ . Cone Pond's SO₄^2? concentrations (126–187 µeq L^?1, mean = 154 µeq L^?1) and δ³⁴S values (2·4 to 4·3 ‰ ) had the smallest ranges of the three watersheds. The range and mean of δ¹⁸O‐SO₄^2? values for Archer Creek and Cone Pond were similar (3·0 to 8·9 ‰ , mean = 4·5 ‰ ; 3·9 to 6·3 ‰ , mean = 4·9 ‰ ; respectively) while δ¹⁸O‐SO₄^2? values for Sleepers River covered a larger range with a lower mean (1·2 to 10·0 ‰ , mean = 2·5). The difference in Sleepers River chemical and isotopic responses was attributed to weathering reactions contributing SO₄^2?. For Archer Creek wetland areas containing previously reduced S compounds that were reoxidized to SO₄^2? probably provided a substantial source of S. Cone Pond had limited internal S sources and less chemical or isotopic response to storms. Differences among the three watersheds in S biogeochemical responses during these storm events were attributed to differences in S mineral weathering contributions, hydrological pathways and landscape features. Further evaluations of differences and similarities in biogeochemical and hydrological responses among watersheds are needed to predict the impacts of climate change. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

A new imaging infrared polarimeter     

J. H. Hough  A. Chrysostomou  J. A. Bailey 《Experimental Astronomy》1994,3(1-4):127-129

A new infrared imaging polarimeter operating in dual-beam mode is described, together with some of the early results.  相似文献