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Currently used and newly proposed calculation techniques for the heightof the stable boundary layer (SBL), including the bulk-Richardson-numbermethod, diagnostic equations for the equilibrium SBL height, and a relaxation-typeprognostic equation, are discussed from the point of view of their physical basis andrelevance to experimental data. Among diagnostic equations, the best fit to data exhibits an advanced Ekman-layer height model derived recently with due regard to the role of the free-flow stability. Its extension to non-steady regimes provides a prognostic equation recommended for use in practical applications. 相似文献
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Douglas A. Simons Paola Amico Dietrich Baade Sam Barden Randall Campbell Gert Finger Kirk Gilmore Roland Gredel Paul Hickson Steve Howell Norbert Hubin Andreas Kaufer Ralf Kohley Philip MacQueen Sergej Markelov Mike Merrill Satoshi Miyazaki Hidehiko Nakaya Darragh O'Donoghue Tino Oliva Andrea Richichi Derrick Salmon Ricardo Schmidt Hongjun Su Simon Tulloch Maria Luisa García Vargas R. Mark Wagner Olivier Wiecha Binxun Ye 《Experimental Astronomy》2005,19(1-3):15-44
Results of a survey of instrumentation and detector systems, either currently deployed or planned for use at telescopes larger than 3.5 m, in ground based observatories world-wide, are presented. This survey revealed a number of instrumentation design trends at optical, near, and mid-infrared wavelengths. Some of the most prominent trends include the development of vastly larger optical detector systems (> 109 pixels) than anything built to date, and the frequent use of mosaics of near-infrared detectors – something that was quite rare only a decade ago in astronomy. Some future science applications for detectors are then explored, in an attempt to build a bridge between current detectors and what will be needed to support the research ambitions of astronomers in the future. 相似文献
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Oleg?MalkovEmail author Aleksej?Mironov Sergej?Sichevskij 《Astrophysics and Space Science》2011,335(1):105-111
Detection of a composite flux in photometry can serve as an indication of a photometrically unresolved binarity and can contribute
to the parameterization of the components of binary systems. A main goal of the present study is to develop a method of automatic
photometric detection of binaries, based on multi-color photometry, theoretical stellar spectral energy distributions and
general understanding of binary evolution. In particular, we consider an ultraviolet photometry where, in combination with
optical and infrared photometry, interstellar reddening can be easier distinguished from temperature reddening. 相似文献
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Are invasive species most successful in habitats of low native species richness across European brackish water seas? 总被引:5,自引:0,他引:5
Marjo Paavola Sergej Olenin Erkki Leppkoski 《Estuarine, Coastal and Shelf Science》2005,64(4):738-750
European brackish water seas (Baltic Sea, Black Sea and Sea of Azov, Caspian Sea) are subject to intense invasion of non-indigenous species (NIS). In these seas, salinity is the most important range limiting factor and native species seem to reach a minimum species richness at intermediate salinities. This trend, revealed by Remane in 1934 and later on confirmed by many other scientists, was compared to the salinity range of already established NIS in the European brackish water seas. It turned out that most NIS are well adapted to the salinities holding lowest native species richness, already in their native area, and that NIS richness maximum in brackish water seas occurs in the salinity intervals of native species richness minimum. A predictable pattern in the salinity range of NIS can be used as a tool in initial risk assessment of future invasions in brackish water seas, especially when mapping highly potential donor and recipient areas. A product of empty niches, suitable environmental conditions, and availability of proper vectors might be the most effective predictor for the invasibility of brackish water areas. 相似文献
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Sergej A. Kitaigorodskii Yury A. Volkov Andrey A. Grachev 《Boundary-Layer Meteorology》1995,76(1-2):181-197
The aerodynamic classification of the resistance laws above solid surfaces is based on the use of a so-called Reynolds roughness number Re
s =h
s
u
*/, whereh
s is the effective roughness height, -viscosity,u
*-friction velocity. The recent experimental studies reported by Toba and Ebuchi (1991), demonstrated that the observed variability of the sea roughness cannot be explained only on the basis of the classification of aerodynamic conditions of the sea surface proposed by Kitaigorodskii and Volkov (1965) and Kitaigorodskii (1968) even though the latter approach gains some support from recent experimental studies (see for example Geernaertet al. 1986). In this paper, an attempt is made to explain some of the recently observed features of the variability of surface roughness (Toba and Ebuchi, 1991; Donelanet al., 1993). The fluctuating regime of the sea surface roughness is also described. It is shown that the contribution from the dissipation subrange to the variability of the sea surface can be very important and by itself can explain Charnock's (1955) regime. 相似文献
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A multi-limit formulation for the equilibrium depth of a stably stratified boundary layer 总被引:1,自引:0,他引:1
Currently no expression for the equilibrium depth of the turbulent stably-stratified boundary layer is available that accounts
for the combined effects of rotation, surface buoyancy flux and static stability in the free flow. Various expressions proposed
to date are reviewed in the light of what is meant by the stable boundary layer. Two major definitions are thoroughly discussed.
The first emphasises turbulence and specifies the boundary layer as a continuously and vigorously turbulent layer adjacent
to the surface. The second specifies the boundary layer in terms of the mean velocity profile, e.g. by the proximity of the
actual velocity to the geostrophic velocity. It is shown that the expressions based on the second definition are relevant
to the Ekman layer and portray the depth of the turbulence in the intermediate regimes, when the effects of static stability
and rotation essentially interfere. Limiting asymptotic regimes dominated by either stratification or rotation are examined
using the energy considerations. As a result, a simple equation for the depth of the equilibrium stable boundary layer is
developed. It is valid throughout the range of stability conditions and remains in force in the limits of a perfectly neutral
layer subjected to rotation and a rotation-free boundary layer dominated by surface buoyancy flux or stable density stratification
at its outer edge. Dimensionless coefficients are estimated using data from observations and large-eddy simulations. Well-known
and widely used formulae proposed earlier by Zilitinkevich and by Pollard, Rhines and Thompson are shown to be characteristic
of the above interference regimes, when the effects of rotation and static stability (due to either surface buoyancy flux,
or stratification at the outer edge of the boundary layer) are roughly equally important. 相似文献
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The introduction of alien species (AS) in marine environments is a factor of disturbance that can be viewed as a pollution agent. Using basic information on abundance and distribution of alien species, we developed an index that classifies AS impacts on native species, communities, habitats and ecosystem functioning. This method can be used to evaluate impact at five different levels of biopollution, fitting within the existing schemes for water quality assessment. Both spatial and temporal comparisons are possible. The assessments may also be used to evaluate management performance where avoidance measures were necessary and assist in preventing further unwanted introductions. Such assessments made for the same areas over time provide opportunities for measuring change in biopollution. We have tested the method using four different well-studied areas within the Baltic Sea (brackish to freshwater environments) for two different times, 20 years apart. Further developments of the scheme may be needed to cover some specific cases and taxonomic groups according to their life history. 相似文献