Diagnostics for Evaluating the Impact of Satellite Observations

  • Nancy L. Baker
  • Rolf H. Langland


The adjoints of the numerical weather prediction (NWP) model and data assimilation system may be used together to objectively determine the observation impact – or whether a given observation platform or observing system improves or degrades the subsequent NWP forecast.

The observation impact is a very specific measure of forecast impact, as it depends upon the choice of forecast metric, the suite of observations assimilated, the data assimilation system, and the NWP forecast model. This chapter presents an overview of data assimilation adjoint theory, the observation impact calculation, and the appropriate choices for the forecast metric. Several applications of the observation adjoint technique are presented to illustrate its usefulness to help identify systematic problems with the observing network, to quantify the value of different observing platforms, to monitor the quality of the observing network, and for channel selection for satellite radiometers.


Forecast Error Data Assimilation System Background Error Background Error Covariance Sensitivity Vector 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Nancy L. Baker
    • 1
  • Rolf H. Langland
  1. 1.Marine Meteorology DivisionNaval Research LaboratoryMontereyUSA

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