MERRA-2 Observing System Time Series
GMAO's MERRA reanalysis included no new satellite observation sources after NOAA-18 in 2005. The consequence is that it has approached the point where the loss of an individual observing system could significantly reduce the quality of the product. MERRA-2 expands on MERRA in that it includes observations from many new data sources, including NOAA-19, Metop-A and -B, Suomi-NPP, and GPS Radio Occultation receivers. These new sources have resulted in a significant increase in the total number of assimilated observations, which now approaches five million per 6-hour assimilation cycle. A large percentage of this increase can be attributed to the addition of three hyperspectral instruments: IASI on Metop-A and –B, and CrIS on Suomi-NPP. It is equally important that the newer generation of microwave sounders is included in MERRA-2.
