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@ARTICLE{Meyer:842125,
      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},
      volume       = {11},
      number       = {1},
      issn         = {1867-8548},
      address      = {Katlenburg-Lindau},
      publisher    = {Copernicus},
      reportid     = {FZJ-2018-00404},
      pages        = {215 - 232},
      year         = {2018},
      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 vertical and 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 9 times better than that of the
                      operational retrieval. HIRDLS provides 2-D spectral
                      information 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 often agree 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 also similar. AIRS has a coarser vertical
                      resolution, which results in an attenuation of the amplitude
                      and coarser vertical wavelengths than for 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 3-D 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 agree
                      well. A strong annual cycle at mid- and high latitudes is
                      found in time series of gravity wave variances at 42 km,
                      which has its maxima during wintertime and its minima during
                      summertime. The variability is largest during austral
                      wintertime at 60° S. 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 complementary to each other. 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) / 244 - Composition and dynamics of the upper
                      troposphere and middle atmosphere (POF3-244)},
      pid          = {G:(DE-HGF)POF3-511 / G:(DE-HGF)POF3-244},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000419988400001},
      doi          = {10.5194/amt-11-215-2018},
      url          = {https://juser.fz-juelich.de/record/842125},
}