Based on one-month of global data for 5 AVHRRs (onboard NOAA-16, -18, -19, and Metop-A, -B), 2 MODISs (onboard Terra and Aqua) and 1 VIIRS (onboard the Suomi National Polar-orbiting Partnership, S-NPP), the number of clear sky pixels increases by ~3%, suggesting a small yet consistent positive effect on the ACSPO cloud mask. In IR37, the global mean M-O biases (~0.2K) and standard deviations (STD<0.5K) remain largely unchanged. In IR11 & IR12, the ECMWF mean biases are reduced by ~0.2K (from the GFS 0.5-0.6K), and become closer to those in IR37. This suggests that ECMWF has more moisture than GFS, which mainly affects the longwave bands. The large warm spots in M-O biases in the tropics seen with GFS implementation are reduced and even reverted to small negative M-O biases, suggesting that ECMWF may slightly overestimate water vapor in the tropics. Additionally, using ECMWF instead of GFS also improves stability of M-O biases, and corresponding Double-Differences, in all three AVHRR bands and derived SSTs.
We plan to include ERA-Interim and MERRA profiles in these analyses, which are critically important for long-term reprocessing of AVHRR data using NOAA ACSPO system.