The use of TOVS cloud-cleared radiances in the NCEP SSI analysis system

With improved assimilation techniques, it is now possible to directly assimilate cloud-cleared radiances, rather than temperature and moisture retrievals, in objective analyses. The direct use of the cloud-cleared radiances became the operational technique for using satellite sounding data at the National Centers for Environmental Prediction (NCEP) in October 1995. The methodology for using the data (including bias correction, ozone analysis, skin temperature analysis, and quality control) are described in this paper. The impact of the direct use of the radiances compared to the previously operational use of satellite sounding data shows considerable improvement in NCEP's forecast skill, especially in the Southern Hemisphere. It is anticipated that additional positive impacts will occur with application of the technique to other remotely sensed data.