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Article
The life cycle of instability features measured from the Andes Lidar Observatory over Cerro Pachon on 24 March 2012
Journal of Geophysical Research: Atmospheres
  • J. H. Hecht, Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, California
  • K. Wan, University of Illinois at Urbana-Champaign
  • L. J. Gelinas, Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, California
  • David C. Fritts, University of Illinois at Urbana-Champaign
  • R. L. Walterscheid, Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, California
  • R. J. Rudy, Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, California
  • A. Z. Liu, Embry-Riddle Aeronautical University
  • S. J. Franke, Utah State University
  • F. A. Vargas, Utah State University
  • Pierre-Dominique Pautet, Utah State University
  • Michael J. Taylor, Utah State University
  • G. R. Swenson, Utah State University
Document Type
Article
Publisher
American Geophysical Union
Publication Date
6-27-2014
DOI
10.1002/2014JD021726
Disciplines
Abstract

The Aerospace Corporation's Nightglow Imager (ANI) observes nighttime OH emission (near 1.6 μm) every 2 s over an approximate 73° field of view. ANI had previously been used to study instability features seen over Maui. Here we describe observations of instabilities seen from 5 to 8 UT on 24 March 2012 over Cerro Pachon, Chile, and compare them with previous results from Maui, with theory, and with Direct Numerical Simulations (DNS). The atmosphere had reduced stability because of the large negative temperature gradients measured by a Na lidar. Thus, regions of dynamical and convective instabilities are expected to form, depending on the value of the Richardson number. Bright primary instabilities are formed with a horizontal wavelength near 9 km and showed the subsequent formation of secondary instabilities, rarely seen over Maui, consistent with the primaries being dynamical instabilities. The ratio of the primary to secondary horizontal wavelength was greater over Chile than over Maui. After dissipation of the instabilities, smaller-scale features appeared with sizes in the buoyancy subrange between 1.5 and 6 km. Their size spectra were consistent with the model of Weinstock (1978) if the turbulence is considered to be increasing. The DNS results produce secondary instabilities with sizes comparable to what is seen in the images although their spectra are somewhat steeper than is observed. However, the DNS results also show that after the complete decay of the primary features, scale sizes considerably smaller than 1 km are produced and these cannot be seen by the ANI instrument.

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Publisher: http://onlinelibrary.wiley.com/doi/10.1002/2014JD021726/abstract

Citation Information
Hecht J.H., Wan K., Gelinas L.J., Fritts D.C., Walterscheid R.L., Rudy R.J., Liu A.Z., Franke S.J., Vargas F.A., Pautet P.-D., Taylor M.J., and Swenson G.R., The life cycle of instability features measured from the Andes Lidar Observatory over Cerro Pachon on 24 March 2012, J. Geophys. Res.: Atmospheres, 119, 14, 8872-8898, 2014