Articles | Volume 35, issue 3
Ann. Geophys., 35, 733–750, 2017
Ann. Geophys., 35, 733–750, 2017

Regular paper 12 Jun 2017

Regular paper | 12 Jun 2017

Mesospheric gravity wave momentum flux estimation using hybrid Doppler interferometry

Andrew J. Spargo1, Iain M. Reid1,2, Andrew D. MacKinnon1, and David A. Holdsworth1,3 Andrew J. Spargo et al.
  • 1Department of Physics, School of Physical Sciences, The University of Adelaide, Adelaide, 5005, Australia
  • 2ATRAD Pty. Ltd., 20 Phillips St., Thebarton, 5031, Australia
  • 3National Security & ISR Division, Defence Science and Technology Group, Edinburgh, 5111, Australia

Abstract. Mesospheric gravity wave (GW) momentum flux estimates using data from multibeam Buckland Park MF radar (34.6° S, 138.5° E) experiments (conducted from July 1997 to June 1998) are presented. On transmission, five Doppler beams were symmetrically steered about the zenith (one zenith beam and four off-zenith beams in the cardinal directions). The received beams were analysed with hybrid Doppler interferometry (HDI) (Holdsworth and Reid, 1998), principally to determine the radial velocities of the effective scattering centres illuminated by the radar. The methodology of Thorsen et al. (1997), later re-introduced by Hocking (2005) and since extensively applied to meteor radar returns, was used to estimate components of Reynolds stress due to propagating GWs and/or turbulence in the radar resolution volume. Physically reasonable momentum flux estimates are derived from the Reynolds stress components, which are also verified using a simple radar model incorporating GW-induced wind perturbations. On the basis of these results, we recommend the intercomparison of momentum flux estimates between co-located meteor radars and vertical-beam interferometric MF radars. It is envisaged that such intercomparisons will assist with the clarification of recent concerns (e.g. Vincent et al., 2010) of the accuracy of the meteor radar technique.

Short summary
Measuring the momentum transport due to gravity waves in the 80–100 km region is important for improving our understanding of the middle atmosphere, but it is still difficult to do at useful spatial scales. Here, we measure it using a method that has not been applied to the problem before, involving Doppler analysis of radar beams from multiple directions. The results are pleasing, and we conclude that the measurements may also be able to be made using cheaper, single-beam radar systems.