Algorithm Improvements on the Assimilation of Radio Occultation Observations to Optimize and Accelerate the Use of COSMIC-2A in Operational NOAA’s Weather Models

In preparation for the launch of COSMIC-2A, NOAA has developed, tested and implemented advanced data assimilation methodologies to improve the use of Radio Occultation (RO) observations. NOAA National Centers for Environmental Prediction (NCEP) are currently assimilating RO observations in its operational NWP data assimilation system. As in most operational NWP centers, RO profiles detected to be contaminated by large vertical gradients of atmospheric refractivity are rejected from the assimilation system, thus limiting the impact of these observations in the lower troposphere. Updated algorithms to better quality control RO profiles under these atmospheric conditions were implemented operationally at NCEP in 2015. However, these quality control reject a significant amount of observations, in particular in the tropical latitudes, which is the geographical area that will be largely sampled with COSMIC-2A. During this talk, we will describe advanced RO data assimilation approaches developed at NOAA, including calibration and validation efforts, and how this work will accelerate and optimize the transition to operations of COSMIC-2A.