Variational Aircraft Temperature Bias Correction in the NCEP's GSI Analysis System
Two other issues are also discussed in this study. One is the lack of tail numbers for AIREP aircraft data, and the impact of AIREP data is presented. The other is the missing nearest second information for the observation time used in the aircraft vertical velocity calculation. In addition to the finite-difference method, a tensioned-splines method is used to obtain more continuously smooth aircraft vertical velocity and mitigate the missing time information.