Reprocessed Advanced Technology Microwave Sounder Data Records for Studying Atmospheric Water Vapor Trend

Advanced Technology Microwave Sounder (ATMS) is the backbone microwave sounder that acquires important information about clouds, temperatures, and water vapor in the atmosphere. The information is critical to weather forecasts and climate studies. The first ATMS unit on Suomi National Polar-orbiting Partnership (S-NPP) was launched on 28^th October, 2011. The second ATMS unit on Joint Polar Satellite System (JPSS) (now NOAA-20, National Oceanic and Atmospheric Administration - 20) was launched on 18^th November, 2017. The third ATMS unit on JPSS-2 (now NOAA-21) was launched on 10^th November, 2022. All three ATMS in the space perform well. The next ATMS on JPSS-3 will be launched in 2028. The last ATMS on JPSS-4 is scheduled for the launch in 2033 and we expect the ATMS in operation till after 2040. In this paper, we introduce the reprocessed S-NNP ATMS data. The S-NPP ATMS data between 11/09/2011 and 10/15/2019 are reprocessed using the latest calibration algorithm that has been operational since 10/15/2019. The reprocessing provides high quality and consistent observations for climate studies.

There are five major S-NPP ATMS science data quality variation events. The first one represents the very first Processing Coefficients Table (PCT) update after launch based on the post launch on-orbit data analysis. The second major event is the implementation of S-NPP antenna pattern correction coefficients on November 14, 2013. The third major event is the fundamental change of the ATMS calibration algorithm. Since March 7, 2017, the Rayleigh-Jean approximation-based temperature calibration algorithm has been updated to a full radiance calibration algorithm for S-NPP ATMS. To match the radiance calibration algorithm, the nonlinearity correction coefficients were also derived from pre-launch thermal vacuum test datasets and implemented with the radiance calibration algorithm update. From the ATMS post-launch pitch maneuver data, the channel dependent reflector emissivity was estimated. During the fourth calibration update event, the PCT table update including the channel dependent reflector emissivity and reflector emissivity correction algorithm update was transitioned to operations on October 15, 2019. Meanwhile, an updated antenna pattern correction coefficient implementation makes the systematic bias between sensor data record (SDR) and simulations further reduced. The last update (fifth major event) is the lunar intrusion correction algorithm and associated coefficients implementation on February 4, 2021.

In this presentation, we studied total precipitable water (TPW) trend using S-NPP ATMS brightness temperatures and the MiRS water vapor profile environmental data record. The direct interpolation of the brightness temperature signals seems opposite to the MiRS TPW results. We are going to explain the mystery at the 10^th American Meteorological Society annual meeting. We will also show whether ATMS data at 1:30 am and 1:30 pm local time alone are suitable to study the TPW trend.