Author: N. W. RosenbergPublisher:
ISBN:
Category : Atmosphere, Upper
Languages : en
Pages : 20
Book Description
Stratospheric Turbulence and Vertical Effective Diffusion Coefficients
Author: N. W. RosenbergPublisher:
ISBN:
Category : Atmosphere, Upper
Languages : en
Pages : 20
Book Description
Tropospheric Stratospheric Turbulence and Vertical Diffusivities
Author: S. P. ZimmermanPublisher:
ISBN:
Category : Atmospheric models
Languages : en
Pages : 22
Book Description
The determination of winds and temperature by rawinsonde allows us to calculate the Richardson number, a measure of atmospheric instability. From this, we can then determine the turbulent atmospheric parameters, diffusivity (K), rate of heat deposition (epsilon), and the vertical turbulent intensity (w2). Comparison of these data, for the spring periods, with contours of residual stratospheric radioactivity demonstrate that, at the tropopause, the isocountours of turbulent diffusivity accurately follow the isodensity contours of the residual radioactivity. We also demonstrate that the rapid cessation of the turbulent diffusivity accurately predicts the level of the tropopause. (Author).
Vertical Transport by Small Scale Stratospheric Turbulence
Author: Edmond M. DewanPublisher:
ISBN:
Category : Atmospheric circulation
Languages : en
Pages : 36
Book Description
This paper reviews the estimates to date of the vertical 'effective diffusion coefficient' for stratospheric small scale turbulence transport, KB. These estimates range (in order of magnitude) from 1.0 sq. meter/s to 0.01 sq. meter/s, that is to say from a value which would make turbulence a dominant factor in stratospheric transport to a value which would make it totally insignificant. Such a large range implies much ignorance in this subject. The various techniques are closely examined and the unanswered experimental questions are exhibited. The conclusion is reached that more experimental work needs to be done before one has a reliable estimate for KB.
Estimates of Vertical Eddy Diffusion Due to Turbulent Layers in the Stratosphere
Author: Edmond M. DewanPublisher:
ISBN:
Category : Atmospheric models
Languages : en
Pages : 36
Book Description
Vertical transport in the stratosphere occurs by many processes and the question of the relative importance of stratified turbulence is considered in the context of a 'vertical stack model' described in a previous report. The 'vertical stack model' was designed to estimate the effect of intermittent turbulent layers (separated by essentially laminar flow) and it is here examined in some detail. In particular, a number of less obvious implications are discussed and a list of experimental tests of the model is suggested. It is concluded that the rate of turbulence for vertical transport in the stratosphere remains an open question.
Mixing in Billow Turbulence and Stratospheric Eddy Diffusion
Author: Edmond M. DewanPublisher:
ISBN:
Category : Atmospheric circulation
Languages : en
Pages : 36
Book Description
In order to estimate the rate of vertical transport due to turbulence in the stratosphere, it is necessary to know the degree of mixing that takes place in 'Kelvin-Helmholtz billow events.' This is estimated by means of a discrete model and the results are compared with published experimental observations. From these considerations it is concluded that a very large degree of mixing probably takes place in such events, and that, therefore, one must use the relation between the bulk vertical eddy diffusivity and layer diffusivity originally proposed by Rosenberg and Dewan instead of the simple one usually employed.
DOT-TSC-OST.
Author: Proceedings of the Third Conference on the Climatic Impact Assessment Program
Author: Anthony J. BroderickPublisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 684
Book Description
Environmental Research Papers
Author: Publisher:
ISBN:
Category : Environmental geology
Languages : en
Pages : 402
Book Description
A One-dimensional Vertical Diffusion Parameter for Extremely Inhomogeneous, Layered Turbulence in Stratified Fluids
Author: Edmond M. DewanPublisher:
ISBN:
Category : Computer simulation
Languages : en
Pages : 54
Book Description
A self-consistent method of characterizing vertical turbulent transport by means of a diffusion parameter is demonstrated for the extremely inhomogeneous case of layered turbulence in a stratified fluid. Between the horizontal turbulent layers, horizontal laminar flow is assumed to occur, and molecular diffusion is ignored. The layers are assumed to occur at random heights with random thickness. An analogy is made between the process of random mixing layers and the finite difference representation of the diffusion equation. It is demonstrated by means of a series of digital computer experiments that, in the case where total mixing takes place within the turbulent layers, the diffusion parameter herein developed is the valid one to use (in contrast to 'eddy diffusivity'). The relation between this inhomogeneous diffusion parameter and practical experimental measurements is given. The motive behind this investigation involves vertical transport of pollution in the environment in general and in the stratosphere in particular.
Theoretical Explanation of Spectral Slopes in Stratospheric Turbulence Data and Implications for Vertical Transport
Author: Edmond M. DewanPublisher:
ISBN:
Category : Atmospheric turbulence
Languages : en
Pages : 58
Book Description
This paper is motivated by the requirement to improve understanding of vertical motion of pollutants in the stratosphere. One method to estimate vertical transport due to the effects of turbulence is by means of the effective diffusivity coefficient. To calculate this parameter, it is often necessary to know the value of epsilon, the rate of turbulent dissipation. This parameter, epsilon, is also important to know in the context of the global numerical stratospheric simulation models now being created for environmental assessment purposes.