Stationary planetary wave propagation in Northern Hemisphere winter – climatological analysis of the refractive index Q. Li1, H.-F. Graf1,2, and M. A. Giorgetta1 1Max Planck Institute for Meteorology, Hamburg, Germany 2Center for Atmospheric Science, University of Cambridge, UK
Abstract. The probability density on a height-meridional plane of negative refractive
index squared f(nk2<0) is introduced as a new analysis tool to
investigate the climatology of the propagation conditions of stationary
planetary waves based on NCEP/NCAR reanalysis data for 44 Northern
Hemisphere boreal winters (1958–2002). This analysis addresses the control
of the atmospheric state on planetary wave propagation. It is found that not
only the variability of atmospheric stability with altitudes, but also the
variability with latitudes has significant influence on planetary wave
propagation. Eliassen-Palm flux and divergence are also analyzed to
investigate the eddy activities and forcing on zonal mean flow. Only the
ultra-long planetary waves with zonal wave number 1, 2 and 3 are
investigated. In Northern Hemisphere winter the atmosphere shows a large
possibility for stationary planetary waves to propagate from the troposphere
to the stratosphere. On the other hand, waves induce eddy momentum flux in
the subtropical troposphere and eddy heat flux in the subpolar stratosphere.
Waves also exert eddy momentum forcing on the mean flow in the troposphere
and stratosphere at middle and high latitudes. A similar analysis is also
performed for stratospheric strong and weak polar vortex regimes,
respectively. Anomalies of stratospheric circulation affect planetary wave
propagation and waves also play an important role in constructing and
maintaining of interannual variations of stratospheric circulation.
Citation: Li, Q., Graf, H.-F., and Giorgetta, M. A.: Stationary planetary wave propagation in Northern Hemisphere winter – climatological analysis of the refractive index, Atmos. Chem. Phys., 7, 183-200, doi:10.5194/acp-7-183-2007, 2007.