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@ARTICLE{Ern:4717,
      author       = {Ern, M. and Preusse, P.},
      title        = {{W}ave fluxes of equatorial {K}elvin waves and{QBO} zonal
                      wind forcing derived from {SABER} and {ECMWF} temperature
                      space-time spectra},
      journal      = {Atmospheric chemistry and physics},
      volume       = {9},
      issn         = {1680-7316},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {PreJuSER-4717},
      pages        = {3957 - 3986},
      year         = {2009},
      note         = {The work of M. Ern was supported by the European Commission
                      (European Union's 6th framework program) within the EC
                      Integrated Project SCOUT-O3 (505390-GOCE-CT-2004). We thank
                      the whole SABER team, in particular M. G. Mlynczak, J. M.
                      Russell III, and L. L. Gordley for providing the excellent
                      data set of SABER temperatures. Thanks also go to the
                      European Centre for Medium-Range Weather Forecasts (ECMWF)
                      for providing the ECMWF operational analyses used. Helpful
                      comments by two anonymous reviewers are acknowledged.},
      abstract     = {The quasi-biennial oscillation (QBO) of the zonal mean
                      zonal wind is a dynamical phenomenon of the tropical middle
                      atmosphere. Influences of the QBO can even be found at mid
                      and high latitudes. It is widely accepted that the phase
                      descent of alternating tropical easterlies and westerlies is
                      driven by atmospheric waves of both global scale (equatorial
                      wave modes like Kelvin, equatorial Rossby, Rossby-gravity,
                      or inertia-gravity waves), as well as mesoscale gravity
                      waves. However, the relative distribution of the different
                      types of waves to the forcing of the QBO winds is highly
                      uncertain. This is the case because until recently there
                      were no high resolution long-term global measurements in the
                      stratosphere. In our study we estimate Kelvin wave momentum
                      flux and the contribution of zonal wind forcing by Kelvin
                      waves based on space-time spectra determined from both
                      Sounding of the Atmosphere using Broadband Emission
                      Radiometry (SABER) temperature measurements as well as
                      temperatures from European Centre for Medium-Range Weather
                      Forecasts (ECMWF) operational analyses. Peak values of total
                      Kelvin wave zonal wind forcing found are about 0.2 m/s/day.
                      There is good agreement between SABER and ECMWF results.
                      Altitude-time cross sections are shown and the results are
                      compared to the total wave forcing required to balance the
                      background atmosphere. Sometimes Kelvin wave forcing is
                      sufficient to explain almost the whole total wave forcing
                      required for the momentum balance during the transition from
                      QBO easterly to westerly winds. This is especially the case
                      during the periods of strong westerly wind shear when the
                      zonal wind is between -20 and 10 m/s at the equator in the
                      altitude range 20 to 35 km. During other parts of the phases
                      of strong westerly wind shear, however, the contribution of
                      Kelvin waves can be comparably low and the missing wave
                      forcing, which is often attributed to mesoscale gravity
                      waves or intermediate scale waves, can be the by far
                      dominant contribution of the QBO forcing. It is also found
                      that seasonal variations of Kelvin wave accelerations could
                      play an important role for the maintenance of the QBO
                      westerly wind jets in the lower stratosphere.},
      keywords     = {J (WoSType)},
      cin          = {ICG-1},
      ddc          = {550},
      cid          = {I:(DE-Juel1)VDB790},
      pnm          = {Atmosphäre und Klima},
      pid          = {G:(DE-Juel1)FUEK406},
      shelfmark    = {Meteorology $\&$ Atmospheric Sciences},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000267324700009},
      url          = {https://juser.fz-juelich.de/record/4717},
}