Thursday, 13 February 2003
An Evaluation of Level-1B and Level-2 AIRS Data Products Using Matched Radiosonde, NCEP and ECMWF Profiles
An evaluation of the Level-1B observed radiances and Level-2 retrievals from the Atmospheric Infrared Sounder (AIRS) data is performed using atmospheric profiles data from collocated global radiosonde measurements, forecast data from the National Center for Environmental Prediction (NCEP), and European Center for Medium Range Weather Forecast (ECMWF) forecasts. At least four months of global collocations representing a diverse set of meteorological conditions have been obtained from the operational processing system at NOAA/NESDIS. The Level-1B radiance observations, and the clear tested, initial cloud cleared, and the final cloud cleared radiances of the AIRS spectrum are compared with the synthetic radiances derived using the Pressure Layer Fast Algorithm for Atmospheric Transmittance (PFAAST) model for a performance evaluation. Preliminary results of the comparison reveal a good agreement between the observed, clear tested, initial and final cloud cleared radiances with the simulations, giving confidence on the cloud clearing and other retrieval algorithms employed in the operational processing system. The AIRS Level-2 atmospheric temperature and moisture profile retrievals derived at NOAA/NESDIS are used for intercomparison with the radiosonde, NCEP and ECMWF profiles. The AIRS retrieved profiles are found to be in good agreement, and within the expected range of errors with the radiosondes, NCEP and ECMWF profiles.