Criterion for analyzing experimental data on eddy diffusion coefficients

• Main Authors: M. N. Vlasov, M. C. Kelley
• Format: Article
• Language: English
• Published: Copernicus Publications 2014-06-01
• Series: Annales Geophysicae
• Online Access: https://www.ann-geophys.net/32/581/2014/angeo-32-581-2014.pdf

Problems exist in estimating the eddy heat transport coefficient, <i>K</i>_eh, from experimental data. These problems are due to uncertainty in determining the turbulent energy dissipation rate and to the uncertainty of <i>K</i>_eh dependence on the energy dissipation rate. In this paper, a new criterion for estimating the eddy heat transport coefficient is suggested. This criterion is based on the effect of eddy turbulence on the energy budget of the upper mesosphere and lower thermosphere. The calculations show high cooling around and above the <i>K</i>_eh peak for <i>K</i>_eh values inferred from experimental data. The cooling rates are much higher than cooling rates corresponding to the temperature given by the MSIS-E-90 model or to temperatures measured during the experiments. The main contribution to high cooling rates is due to the term with eddy heat conduction, which strongly depends on the <i>K</i>_eh gradient. According to our results, the heating/cooling values below the <i>K</i>_eh peak altitude correspond to the temperature given by the MSIS-E-90 model, but at the peak and above, the cooling rates are larger by a factor of 2–3 than the rates corresponding to the temperatures. This means that the <i>K</i>_eh values in the peak and above may be overestimated. Application of this criterion to the Turbulent Oxygen Mixing Experiment (TOMEX) data shows that eddy diffusions inferred from observing chemical tracers in TOMEX are strongly overestimated.