Expand All-Sky Radiance Data Assimilation to ATMS in the NCEP's GFS System

The capability of all-sky microwave radiance assimilation in the Gridpoint Statistical Interpolation (GSI) analysis system had been developed at the National Centers for Environmental Prediction (NCEP), and the all-sky assimilation of radiances from the Advanced Microwave Sounding Unit-A (AMSU-A) microwave radiometer for ocean Field of Views became operational in the Global Forecast System (GFS) on May 12, 2016. Since then progress has been made on expanding the all-sky capability to radiances from the Advanced Technology Microwave Sounder (ATMS).

ATMS has 22 channels, combining most of the channels from AMSU-A and Microwave Humidity Sounder (MHS). ATMS is different from AMSU-A and MHS in beam width, number of field of views, and scan swath width. Some channels also have different frequency/polarization. In this study, quality control procedures due to unique ATMS features and for MHS-like channels are discussed, the observation error assignment is examined, and the results of all-sky ATMS radiance impact experiments are presented.

In addition to the expansion of all-sky radiance assimilation to ATMS, several important issues are in their early phase of development for the more general enhancements, such as the strategies on handling convective clouds in the all-sky radiance assimilation and the application of variational quality control to radiances.