A Brief Overview of the DAO Data Assimilation System
Tuesday, April 30, 2002 - 1:30pm - 2:15pm
Ricardo Todling (National Aeronautics and Space Administration (NASA))
The NASA/DAO data assimilation system has been operational since December 1999 in support of the NASA/Terra satellite. A few features make the analysis in this assimilation system particularly unique: an adaptive buddy check for the online quality control of observations; a bias estimation and correction procedure; the capability to estimate analysis errors; and the capability to perform retrospective data assimilation. By adjusting the prescribed error statistics on the fly the adaptive buddy check in the quality control allows for decisions to be in better agreement with synoptic situations than when quality control decisions are based only on static prescribed error statistics. The bias estimation approach permits reduction of the slowly varying component of forecast (model) biases that would otherwise deteriorate the quality of the analysis. Analysis error estimates maybe used, among other things, as initial conditions to procedures under development for predicting forecast errors. The retrospective analysis procedure, based on the fixed-lag Kalman smoother, allows for generation of improved analyses through the use of observations past any give analysis time. Illustrations of the benefits from these features in Terra data assimilation system will be presented.