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Specific Features of Eddy Turbulence in the Turbopause Region : Volume 32, Issue 4 (15/04/2014)

By Vlasov, M. N.

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Book Id: WPLBN0004002449
Format Type: PDF Article :
File Size: Pages 12
Reproduction Date: 2015

Title: Specific Features of Eddy Turbulence in the Turbopause Region : Volume 32, Issue 4 (15/04/2014)  
Author: Vlasov, M. N.
Volume: Vol. 32, Issue 4
Language: English
Subject: Science, Annales, Geophysicae
Collections: Periodicals: Journal and Magazine Collection, Copernicus GmbH
Historic
Publication Date:
2014
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications

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Kelley, M. C., & Vlasov, M. N. (2014). Specific Features of Eddy Turbulence in the Turbopause Region : Volume 32, Issue 4 (15/04/2014). Retrieved from http://worldebookfair.com/


Description
Description: School of Electrical and Computer Engineering, Cornell University, Ithaca, NY, USA. The turbopause region is characterized by transition from the mean molecular mass (constant with altitude) to the mean mass (dependent on altitude). The former is provided by eddy turbulence, and the latter is induced by molecular diffusion. Competition between these processes provides the transition from the homosphere to the heterosphere. The turbopause altitude can be defined by equalizing the eddy and molecular diffusion coefficients and can be located in the upper mesosphere or the lower thermosphere. The height distributions of chemical inert gases very clearly demonstrate the transition from turbulent mixing to the diffusive separation of these gases. Using the height distributions of the chemical inert constituents He, Ar, and N2 given by the MSIS-E-90 model and the continuity equations, the height distribution of the eddy diffusion coefficient in the turbopause region can be inferred. The eddy diffusion coefficient always strongly reduces in the turbopause region. According to our results, eddy turbulence above its peak always cools the atmosphere. However, the cooling rates calculated with the eddy heat transport coefficient equaled to the eddy diffusion coefficient were found to be much larger than the cooling rates corresponding to the neutral temperatures given by the MSIS-E-90 model. The same results were obtained for the eddy diffusion coefficients inferred from different experimental data. The main cause of this large cooling is the very steep negative gradient of the eddy heat transport coefficient, which is equal to the eddy diffusion coefficient if uniform turbulence takes place in the turbopause region. Analysis of wind shear shows that localized turbulence can develop in the turbopause region. In this case, eddy heat transport is not so effective and the strong discrepancy between cooling induced by eddy turbulence and cooling corresponding to the temperature given by the MSIS-E-90 model can be removed.

Summary
Specific features of eddy turbulence in the turbopause region

Excerpt
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