Improved NESDIS cloud retrieval algorithm using HIRS2-MSU radiance measurements: method in product characteristics

Response characteristics of the channel pairs and the effect of the adjustment for atmospheric attenuations from the NOAA/NESDIS HIRS2-MSU cloud retrieval algorithm are illustrated and discussed. This improved algorithm of L.M. McMillin et al. (1994) differs from other similar “slice methods”, uses two iterations of various channel pairs for tuning the estimations of cloud top heights, and enhances the accuracy of effective cloud amounts. Full utilization of the information from possible channel pairs enhances the resultant accuracy. Characteristics of cloud-top heights and cloud amounts according to the channel pairs are illustrated. It is shown that the attenuation above the clouds plays an important role in determining cloud profiles. Without an adjustment for atmospheric attenuation above the clouds, it would separate cloud distribution to two levels for the mid-low level clouds. Both the adjustment of attenuation and the second iteration have an effect in reducing the total cloud amount