% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@ARTICLE{Schwinger:14007,
      author       = {Schwinger, J. and Elbern, H.},
      title        = {{C}hemical state estimation for the middle atmosphere by
                      four-dimensional variational data assimilation: {A}
                      posteriori validation of error statistics in observation
                      space},
      journal      = {Journal of Geophysical Research},
      volume       = {115},
      issn         = {0148-0227},
      address      = {Washington, DC},
      publisher    = {Union},
      reportid     = {PreJuSER-14007},
      pages        = {D18307},
      year         = {2010},
      note         = {We are grateful to the European Space Agency (ESA) for
                      providing MIPAS data. SAGE II data were obtained from NASA
                      Langley Research Center, and HALOE data were made available
                      by Hampton University, Virginia and NASA Langley Research
                      Center. Meteorological analyses for initialization of GME
                      were obtained from the European Centre for Medium-Range
                      Weather Forecasts (ECMWF). Further, we are grateful to the
                      team at University of Cologne's computer center (RRZK) for
                      their support and provision of computational resources. This
                      work was funded by the German Federal Ministry of Education
                      and Research in the frame of the funding program AFO 2000
                      with the grant FZK 07ATF48. The authors would like to thank
                      three anonymous reviewers for their comments and
                      suggestions, which helped to improve the manuscript.},
      abstract     = {Chemical state analyses of the atmosphere based on data
                      assimilation may be degraded by inconsistent covariances of
                      background and observation errors. An efficient method to
                      calculate consistency diagnostics for background and
                      observation errors in observation space is applied to
                      analyses of the four-dimensional variational stratospheric
                      chemistry data assimilation system SACADA (Synoptic Analysis
                      of Chemical Constituents by Advanced Data Assimilation). A
                      background error covariance model for the assimilation of
                      Michelson Interferometer for Passive Atmospheric Sounding
                      (MIPAS) ozone retrievals is set up and optimized. It is
                      shown that a significant improvement of the assimilation
                      system performance is attained through the use of this
                      covariance model compared to a simple covariance
                      formulation, which assumes background errors to be a fixed
                      fraction of the field value. The forecast skill, measured by
                      the distance between the model forecast and MIPAS
                      observations, is shown to improve. Further, an evaluation of
                      analyses with independent data from the Halogen Observation
                      Experiment (HALOE), the Stratospheric Aerosol and Gas
                      Experiment II (SAGE II), and ozone sondes reveals that the
                      standard deviation of ozone analyses with respect to these
                      instruments is reduced throughout the middle stratosphere.
                      Compared to the impact of background error variances on
                      analysis quality, it is found that the precise specification
                      of spatial background error correlations appears to be less
                      critical if observations are spatially and temporally dense.
                      Results indicate that ozone forecast errors of a state of
                      the art stratospheric chemistry assimilation system are of
                      the same order of magnitude as MIPAS observation errors.},
      keywords     = {J (WoSType)},
      cin          = {IEK-8},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-8-20101013},
      pnm          = {Atmosphäre und Klima},
      pid          = {G:(DE-Juel1)FUEK491},
      shelfmark    = {Meteorology $\&$ Atmospheric Sciences},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000282321400002},
      doi          = {10.1029/2009JD013115},
      url          = {https://juser.fz-juelich.de/record/14007},
}