Articles | Volume 27, issue 8
Ann. Geophys., 27, 3213–3224, 2009
https://doi.org/10.5194/angeo-27-3213-2009

Special issue: 12th International Symposium on Equatorial Aeronomy...

Ann. Geophys., 27, 3213–3224, 2009
https://doi.org/10.5194/angeo-27-3213-2009

  19 Aug 2009

19 Aug 2009

Analysis and modeling of ducted and evanescent gravity waves observed in the Hawaiian airglow

D. B. Simkhada1, J. B. Snively1, M. J. Taylor1, and S. J. Franke2 D. B. Simkhada et al.
  • 1Utah State University, Center for Atmospheric and Space Sciences, 4405 Old Main Hill, Logan, UT 84322-4405, USA
  • 2University of Illinois at Urbana-Champaign, Department of Electrical and Computer Engineering, 320 CSL, 1308 W. Main Street, Urbana, IL 61801, USA

Abstract. Short-period gravity waves of especially-small horizontal scale have been observed in the Maui, Hawaii airglow. Typical small-scale gravity wave events have been investigated, and intrinsic wave propagation characteristics have been calculated from simultaneous meteor radar wind measurements. Here we report specific cases where wave structure is significantly determined by the local wind structure, and where wave characteristics are consistent with ducted or evanescent waves throughout the mesopause region. Two of the documented events, exhibiting similar airglow signatures but dramatically different propagation conditions, are selected for simple numerical modeling case studies. First, a Doppler-ducted wave trapped within relatively weak wind flow is examined. Model results confirm that the wave is propagating in the 85–95 km region, trapped weakly by evanescence above and below. Second, an evanescent wave in strong wind flow is examined. Model results suggest an opposite case from the first case study, where the wave is instead trapped above or below the mesopause region, with strong evanescence arising in the 85–95 km airglow region. Distinct differences between the characteristics of these visibly-similar wave events demonstrate the need for simultaneous observations of mesopause winds to properly assess local propagation conditions.