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@ARTICLE{Meyer:837864,
      author       = {Meyer, Catrin I. and Ern, Manfred and Hoffmann, Lars and
                      Trinh, Quang Thai and Alexander, M. Joan},
      title        = {{I}ntercomparison of {AIRS} and {HIRDLS} stratospheric
                      gravity wave observations},
      journal      = {Atmospheric measurement techniques discussions},
      volume       = {-},
      issn         = {1867-8610},
      address      = {Katlenburg-Lindau},
      publisher    = {Copernicus},
      reportid     = {FZJ-2017-06641},
      pages        = {1 - 33},
      year         = {2017},
      abstract     = {We investigate stratospheric gravity wave observations by
                      the Atmospheric InfraRed Sounder (AIRS) aboard NASA's Aqua
                      satellite and the High Resolution Dynamics Limb Sounder
                      (HIRDLS) aboard NASA's Aura satellite. AIRS operational
                      temperature retrievals are typically not used for studies of
                      gravity waves, because their horizontal resolution is rather
                      limited. This study uses data of a high-resolution retrieval
                      which provides stratospheric temperature profiles for each
                      individual satellite footprint. Therefore the horizontal
                      sampling of the high-resolution retrieval is nine times
                      better than that of the operational retrieval. HIRDLS
                      provides 2D spectral formation of observed gravity waves in
                      terms of along-track and vertical wavelengths. AIRS as a
                      nadir sounder is more sensitive to short horizontal
                      wavelength gravity waves and HIRDLS as a limb sounder is
                      more sensitive to short vertical wavelength gravity waves.
                      Therefore HIRDLS is ideally suited to complement AIRS
                      observations. A calculated momentum flux factor indicates
                      that the waves seen by AIRS contribute significantly to
                      momentum flux, even if the AIRS temperature variance may be
                      small compared to HIRDLS. The stratospheric wave structures
                      observed by AIRS and HIRDLS agree often very well. Case
                      studies of a mountain wave event and a non-orographic wave
                      event demonstrate that the observed phase structures of AIRS
                      and HIRDLS are conform. AIRS has a coarser vertical
                      resolution, which results in an attenuation of the amplitude
                      and coarser vertical wavelengths compared to HIRDLS.
                      However, AIRS has a much higher horizontal resolution and
                      the propagation direction of the waves can be clearly
                      identified in geographical maps. The horizontal orientation
                      of the phase fronts can be deduced from AIRS 3D temperature
                      fields. This is a restricting factor for gravity wave
                      analyses of limb measurements. Additionally, temperature
                      variances with respect to stratospheric gravity wave
                      activity are compared on a statistical basis. The complete
                      HIRDLS measurement period from January 2005 to March 2008 is
                      covered. The seasonal and latitudinal distributions of
                      gravity wave activity as observed by AIRS and HIRDLS fit
                      well. A strong annual cycle at mid and high latitudes is
                      found in time series of gravity wave variances at 42 km,
                      which has during wintertime its maxima and during summertime
                      its minima. During austral wintertime at 60° S the
                      variability is largest. Variations in the zonal winds at
                      2.5 hPa are associated with large variability in gravity
                      wave variances. Altogether, gravity wave variances of AIRS
                      and HIRDLS are conform and complementary to each other.
                      Thereby large parts of the gravity wave spectrum are covered
                      by joint observations. This opens up fascinating vistas for
                      future gravity wave research.},
      cin          = {JSC / IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)JSC-20090406 / I:(DE-Juel1)IEK-7-20101013},
      pnm          = {511 - Computational Science and Mathematical Methods
                      (POF3-511)},
      pid          = {G:(DE-HGF)POF3-511},
      typ          = {PUB:(DE-HGF)16},
      doi          = {10.5194/amt-2017-235},
      url          = {https://juser.fz-juelich.de/record/837864},
}