Channel selection in WRFDA is controlled by radiance ‘info’ files, located in the sub-directory radiance_info, under the working directory. These files are separated by satellites and sensors; e.g., noaa-15-amsua.info, noaa-16-amsub.info, dmsp-16-ssmis.info and so on. An example of 5 channels from noaa-15-amsub.info is shown below. The fourth column is used by WRFDA to control when to use a corresponding channel. Channels with the value “-1” in the fourth column indicate that the channel is “not assimilated,” while the value “1” means “assimilated.” The sixth column is used by WRFDA to set the observation error for each channel. Other columns are not used by WRFDA. It should be mentioned that these error values might not necessarily be optimal for your applications. It is the user’s responsibility to obtain the optimal error statistics for his/her own applications.