Equatorial wave analysis from SABER and ECMWF temperatures M. Ern1, P. Preusse1, M. Krebsbach1,*, M. G. Mlynczak2, and J. M. Russell III3 1Institute of Chemistry and Dynamics of the Geosphere (ICG-1), Forschungszentrum Juelich, Juelich, Germany 2Atmospheric Sciences Division, NASA Langley Research Center, Hampton, VA, USA 3Center for Atmospheric Sciences, Hampton University, Hampton, VA, USA *now at: Department of Physics, University of Wuppertal, Wuppertal, Germany
Abstract. Equatorial planetary scale wave modes such as Kelvin waves or Rossby-gravity
waves are excited by convective processes in the troposphere.
In this paper an analysis for these and other equatorial
wave modes is carried out with special focus on the stratosphere
using temperature data from the SABER satellite instrument as well as ECMWF
Space-time spectra of symmetric and antisymmetric spectral power
are derived to separate the different equatorial wave types and
the contribution of gravity waves is determined
from the spectral background of the space-time spectra.
Both gravity waves and equatorial planetary scale wave modes are main drivers
of the quasi-biennial oscillation (QBO) in the stratosphere. Temperature
variances attributed to the different wave types are calculated for the
period from February 2002 until March 2006 and compared to previous findings.
A comparison between SABER and ECMWF wave analyses shows that in the lower
stratosphere SABER and ECMWF spectra and temperature variances agree
remarkably well while in the upper stratosphere ECMWF tends to overestimate
Kelvin wave components. Gravity wave variances are partly reproduced by ECMWF
but have a significant low-bias. For the examples of a QBO westerly phase
(October–December 2004) and a QBO easterly phase (November/December 2005,
period of the SCOUT-O3 tropical aircraft campaign in Darwin/Australia) in the
lower stratosphere we find qualitatively good agreement between SABER and
ECMWF in the longitude-time distribution of Kelvin, Rossby (n=1), and
Citation: Ern, M., Preusse, P., Krebsbach, M., Mlynczak, M. G., and Russell III, J. M.: Equatorial wave analysis from SABER and ECMWF temperatures, Atmos. Chem. Phys., 8, 845-869, doi:10.5194/acp-8-845-2008, 2008.