ON THE ACCURACY OF TOVS TEMPERATURE-FIELDS IN AN ARCTIC CASE-STUDY

Temperature profiles from NOAA 10 data were retrieved with the International TOVS Processing Package software using different initial estimates and compared to radiosonde profiles and the European Center for Medium-Range Weather Forecasts analysis. To assess the limits of their accuracy, the delta correction was updated for the microwave sounding unit with the analysis and the measurements of two days before and completed by its scan angle dependence. The HIRS cloud detection with the CO2 slicing method showed satisfactory results compared to a cloud mask from advanced very high resolution radiometer data. Error statistics for retrievals with 1 field of view (FOV) and 3 x 3 FOVs revealed similar values. With the forecast as a first guess, a rms <2 K and a bias <1 K for p < 850 hPa are found in the comparison with radiosondes but with a strong dependence on the errors of the delta correction. The error statistics of the forecast compared to analysis and radiosondes showed no advantages for TOVS retrievals in this case study.