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Ann. Geophys., 25, 475-481, 2007
www.ann-geophys.net/25/475/2007/
© European Geosciences Union 2007
Eddy turbulence parameters inferred from radar observations at Jicamarca
M. N. Vlasov1, M. C. Kelley1, and D. L. Hysell2
1School of Electrical and Computer Engineering, Cornell University, 320 Rhodes Hall, Ithaca, New York, 14853, USA
2Department of Earth and Atmospheric Science, Cornell University, 2108 Snee Hall, Ithaca, New York, 14853, USA
Abstract. Significant electron density striations, neutral temperatures 27 K above
nominal, and intense wind shear were observed in the E-region ionosphere
over the Jicamarca Radio Observatory during an unusual event on 26 July 2005
(Hysell et al., 2007). In this paper, these results
are used to estimate eddy turbulence parameters and their effects. Models
for the thermal balance in the mesosphere/lower thermosphere and the charged
particle density in the E region are developed here. The thermal balance
model includes eddy conduction and viscous dissipation of turbulent energy
as well as cooling by infrared radiation. The production and recombination
of ions and electrons in the E region, together with the production and
transport of nitric oxide, are included in the plasma density model. Good
agreement between the model results and the experimental data is obtained
for an eddy diffusion coefficient of about 1×103 m2/s at
its peak, which occurs at an altitude of 107 km. This eddy turbulence
results in a local maximum of the temperature in the upper mesosphere/lower
thermosphere and could correspond either to an unusually high mesopause or
to a double mesosphere. Although complicated by plasma dynamic effects and
ongoing controversy, our interpretation of Farley-Buneman wave phase
velocity (Hysell et al., 2007) is consistent with a low
Brunt-Väisälä frequency in the region of interest. Nitric oxide
transport due to eddy diffusion from the lower thermosphere to the
mesosphere causes electron density changes in the E region whereas NO
density modulation due to irregularities in the eddy diffusion coefficient
creates variability in the electron density.
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