Radiance bias correction in the National Centers for Environmental Prediction's Gridpoint Statistical Interpolation
This study examined and enhanced several aspects of the radiance bias correction problem. First, a new pre-conditioning was applied to the bias correction coefficients in order to allow the removal of pre-specified predictor parameters. Second, the background error variances for the bias correction coefficients were automatically adjusted using an approximation of the analysis error variances from previous cycles. Third, the capability to perform bias correction for passive channels within the GSI was developed.
The two step bias correction procedure currently used was replaced with a single variational bias correction scheme within the GSI. Numerous tests of the new scheme have been run. Due to the interaction between the radiance bias correction scheme and radiance quality control, different approaches of initializing the correction scheme have been tested and their analysis and forecast impacts assessed. Results from these tests will be presented at the conference.