A technical comment: Analysis of ‘examination of “global atmospheric temperature monitoring with satellite microwave measurements”’     

Roy W. Spencer  John R. Christy  Norman C. Grody 《Climatic change》1996,33(4):477-489

The potential for residual hydrometeor contamination effects in the global temperature time series produced by Spencer and Christy from MSU channel 2 (MSU2) data has been addressed by Prabhakara et al. (1995, 1996). They use tropical oceanic MSU channel l (MSU1) data to estimate the hydrometeor effects on MSU2. We present several lines of evidence to show that their technique greatly overestimates the hydrometeor effects on MSU2. This overestimation is due to the faulty assumption that the hydrometeors that cause MSU1 warming are the same as (or always exist with) the hydrometeors that cause cooling in MSU2. Instead, the hydrometeors responsible for MSU1 warming are liquid phase, while those responsible for MSU2 cooling are large ice particles. Because liquid phase clouds are much more widespread than the large-ice portions of deep convective systems, their method greatly overestimates the areal coverage of contaminated tropical MSU2 data. In addition, we show that the convective screening procedure of Spencer and Christy removes the negative correlation between MSU1 and MSU2 their conclusions rest upon. Radiosonde validation of monthly tropical MSU2 anomalies over the tropical West Pacific also support these conclusions.  相似文献   

Etats-Unis: American Geophysical Union: Annual Meeting of 1959 the Evening Session, the Section of Geodesy and the General Assembly     

Norman F. Braaten 《Journal of Geodesy》1959,33(4):67-74

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Gradual entrainment of a chemical layer at the base of the mantle by overlying convection     

Norman H. Sleep 《Geophysical Journal International》1988,95(3):437-447

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Thermal Contraction and Flexure of Mid-Continent and Atlantic Marginal Basins   总被引：1，自引：0，他引：1  

Norman H. Sleep  N. Stephen Snell 《Geophysical Journal International》1976,45(1):125-154

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A useful tool for image enhancement     

Norman A. Andresen 《Journal of Paleolimnology》2003,30(4):461-464

Image enhancement provides a means to facilitate information transfer without altering the image information. A plug-in for the commonly used image capture and manipulation program Photoshop is discussed as one useful tool.  相似文献   

Pathogenicity of vibrios in fish: An overview   总被引：1，自引：0，他引：1  

Norman Y.S.Woo 《中国海洋大学学报(英文版)》2003,2(2):117-128

Bacteria of the genus Vibrio are ubiquitously distributed in the marine environment. Due to the rapid expansion of intensive mariculture and the consequent deterioration of culture conditions, more and more Vibrio spp. have been recognized as pathogenic agents in outbreaks of vibriosis, a serious epizootic disease affecting most wild and farmed fish species worldwide, which has become the most important limiting factor for the development of intensive mariculture industry. Attempts have been made to understand the pathogenicity of vibrios in host fish with the ultimate aim of elucidating the best means for disease control. After an extensive literature survey of the recent advances in the field of fish vibriosis, the pathological changes, virulence factors and associated potential pathogenic mechanisms, transmission routes and related environmental factors involved in outbreak of vibriosis, as well as the controlling strategies are reviewed in the present paper.  相似文献   

Halo Profiles and the Nonlinear Two- and Three-Point Correlation Functions of Cosmological Mass Density     

Ma CP  Fry JN 《The Astrophysical journal》2000,535(2):L87-L90

NGC 4945 is one of the brightest Seyfert galaxies on the sky at 100 keV, but is completely absorbed below 10 keV; its absorption column is probably the largest that still allows a direct view of the nucleus at hard X-ray energies. Our observations of it with the Rossi X-Ray Timing Explorer (RXTE) satellite confirm the large absorption, which for a simple phenomenological fit using an absorber with solar abundances implies a column of 4.5+0.4-0.4x1024 cm(-2). Using a more realistic scenario (requiring Monte Carlo modeling of the scattering), we infer the optical depth to Thomson scattering of approximately 2.4. If such a scattering medium were to subtend a large solid angle from the nucleus, it should smear out any intrinsic hard X-ray variability on timescales shorter than the light-travel time through it. The rapid (with a timescale of approximately 1 day) hard X-ray variability of NGC 4945 discovered by us with RXTE implies that the bulk of the extreme absorption in this object does not originate in a parsec-size, geometrically thick molecular torus. Instead, the optically thick material on parsec scales must be rather geometrically thin, subtending a half-angle less than 10 degrees, and it is likely to be the same disk of material that is responsible for the water maser emission observed in NGC 4945. Local number counts of Seyfert 1 and Seyfert 2 galaxies show a large population of heavily obscured active galactic nuclei (AGNs) which are proposed to make up the cosmic X-ray background (CXRB). However, for this to be the case, the absorption geometry in the context of axially symmetric unification schemes must have the obscuring material subtending a large scale height-contrary to our inferences about NGC 4945-implying that NGC 4945 is not a prototype of obscured AGNs postulated to make up the CXRB. The small solid angle of the absorber, together with the black hole mass (of approximately 1.4x106 M( middle dot in circle)) from megamaser measurements, allows a robust determination of the nuclear luminosity, which in turn implies that the source radiates at approximately 10% of the Eddington limit.  相似文献   

Selection of ground motion time series and limits on scaling   总被引：4，自引：0，他引：4  

Jennie Watson-Lamprey  Norman Abrahamson 《Soil Dynamics and Earthquake Engineering》2006,26(5):477-482

A procedure to select time series for use in non-linear analyses that are intended to result in an average response of the non-linear system is proposed that is not based simply on magnitude, distance, and spectral shape. A simple model of a yielding system is used as a proxy for the non-linear behavior of a more complicated yielding system. As an example, Newmark displacements are used as a proxy for more complex slope-stability models. The candidate scaled time series are evaluated to find those that yield a response of the simple non-linear system that is near the expected response for the design event. Those scaled time series with responses near the expected value are selected as the optimum time series for defining average response even if the scale factors are larger than commonly accepted (e.g. scale factors >factor of 2).  相似文献   

Position of the Gulf Stream influences lake nitrate concentrations in SW Ireland     

Eleanor Jennings  Norman Allott 《Aquatic Sciences - Research Across Boundaries》2006,68(4):482-489

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Influence of freeze-thaw events on carbon dioxide emission from soils at different moisture and land use     

Irina Kurganova  Robert Teepe  Norman Loftfield 《Carbon balance and management》2007,2(1):2-9

Background  

The repeated freeze-thaw events during cold season, freezing of soils in autumn and thawing in spring are typical for the tundra, boreal, and temperate soils. The thawing of soils during winter-summer transitions induces the release of decomposable organic carbon and acceleration of soil respiration. The winter-spring fluxes of CO₂ from permanently and seasonally frozen soils are essential part of annual carbon budget varying from 5 to 50%. The mechanisms of the freeze-thaw activation are not absolutely clear and need clarifying. We investigated the effect of repeated freezing-thawing events on CO₂ emission from intact arable and forest soils (Luvisols, loamy silt; Central Germany) at different moisture (65% and 100% of WHC).  相似文献