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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 29, issue 11
Ann. Geophys., 29, 2019-2029, 2011
https://doi.org/10.5194/angeo-29-2019-2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 29, 2019-2029, 2011
https://doi.org/10.5194/angeo-29-2019-2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.

Regular paper 15 Nov 2011

Regular paper | 15 Nov 2011

Estimates of vertical eddy diffusivity in the upper mesosphere in the presence of a mesospheric inversion layer

R. L. Collins1, G. A. Lehmacher2, M. F. Larsen2, and K. Mizutani3 R. L. Collins et al.
  • 1Geophysical Institute and Department of Atmospheric Sciences, University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775-7320, USA
  • 2Department of Physics and Astronomy, Clemson University, 118 Kinard Laboratory, Clemson, SC 29631-0978, USA
  • 3Environmental Sensing and Network Group, National Institute of Information and Communications Technology, 4-2-1 Nukui-kita, Koganei, Tokyo 184-8795, Japan

Abstract. Rayleigh and resonance lidar observations were made during the Turbopause experiment at Poker Flat Research Range, Chatanika Alaska (65° N, 147° W) over a 10 h period on the night of 17–18 February 2009. The lidar observations revealed the presence of a strong mesospheric inversion layer (MIL) at 74 km that formed during the observations and was present for over 6 h. The MIL had a maximum temperature of 251 K, amplitude of 27 ± 7 K, a depth of 3.0 km, and overlying lapse rate of 9.4 ± 0.3 K km−1. The MIL was located at the lower edge of the mesospheric sodium layer. During this coincidence the lower edge of the sodium layer was lowered by 2 km to 74 km and the bottomside scale height of the sodium increased from 1 km to 15 km. The structure of the MIL and sodium are analyzed in terms of vertical diffusive transport. The analysis yields a lower bound for the eddy diffusion coefficient of 430 m2 s−1 and the energy dissipation rate of 2.2 mW kg−1 at 76–77 km. This value of the eddy diffusion coefficient, determined from naturally occurring variations in mesospheric temperatures and the sodium layer, is significantly larger than those reported for mean winter values in the Arctic but similar to individual values reported in regions of convective instability by other techniques.

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