Assessing the Use of Satellite Observations in the NASA Modern Era Reanalysis for Research and Applications, Version-2 (MERRA-2)

NASA MERRA-2 is an atmospheric reanalysis generated using the Goddard Earth Observing System, Version-5 (GEOS-5) data assimilation system at the Global Modeling and Assimilation Office (GMAO). While the system has land and aerosol modeling and analysis components, this talk will focus on the observations that impact the atmospheric analysis, which is based on the Gridpoint Statistical Interpolation (GSI) routine.

While conventional and non-radiance satellite observations will be considered, a significant portion of this talk will focus on the use of satellite radiance observations. MERRA-2 incorporates core satellite observations from NASA, NOAA, and DoD satellites, beginning with the base of the TIROS Operational Vertical Sounder (TOVS) instruments and advancing through the Special Sensor Microwave/Imager (SSM/I), Advanced TOVS (ATOVS), and NASA Earth Observing System (EOS) periods. Per every six hour analysis, observation usage has grown from ~150,000 in the earliest period to having recently eclipsed 5 million observations. The behavior of these observations and the reaction of the system to these observations are being assessed and will be presented.