Cloud parameters and temperature profile retrieval from infrared sounder data

An inversion method is applied to the remote sensing of atmospheric temperature profiles in the presence of clouds. The method simultaneously calculates cloud-top pressure, amount, and spectral emissivity, along with the temperature profile retrieval. Numerical analyses and retrieval experiments are carried out by using simulated sounder data. The sensitivity of the computed radiances to measurement noise and numerical errors is also examined. The retrieval results are physically discussed and numerically compared with the model atmospheric profiles. Comparisons reveal that the noise effect is more pronounced for thinner and/or smaller fractional cloud cases. It is also noted that the cloud thickness variation has a slight effect on temperature retrieval. Experiments on the proposed algorithm are carried out utilizing the High Resolution Infrared Sounder (HIRS) data of NOAA-6 and TIROS-N. Although the results of the experiments are difficult to verify quantitatively, the retrieved cloud cover and temperature field at 500 and 700 mb compare reasonably well with the synoptic reports and GOES satellite images. (Author)