Advances in Suomi NPP ATMS SDR Life-Cycle Reprocessing

Suomi National Polar-orbiting Partnership (S-NPP) was launched on October 28, 2011. After more than five years of on-orbit operations, the Advanced Technology Microwave Sounder (ATMS) instrument on-board S-NPP, as the first of its series, is still providing high quality atmospheric temperature and moisture sounding observations for operational weather and climate applications. During the 5+ years of on-orbit operations, the ATMS ground processing system implemented by Interface Data and Processing Segment (IDPS) has been experienced multiple updates to improve data quality by updating calibration logarithm and coefficients. Due to the properties of real time ground processing system, improvement updates are only applied to the observations afterwards but not those in the past. Therefore, users may see discontinuities if the life time data trends are studied and compared with observations of other microwave instruments. As the lead of ATMS calibration/validation sciences team, STAR ATMS SDR team keeps all the records of historical calibration anomalies, calibration algorithm updates, and calibration coefficients updates. To provide a consistent and stable ATMS data records, STAR ATMS SDR team conducted the S-NPP ATMS SDR life-cycle reprocessing. Several major improvements in this set of data records include the transition of full radiance based calibration algorithm from Rayleigh-Jeans approximate based calibration algorithm and corresponding calibration coefficients update, correction of non-linearity correction coefficients, lunar intrusion detection and correction, and data gaps filling. The reprocessing data records are from November 7, 2011, which is the first day ATMS starts providing science data, to March 8, 2017, which is the day that Block2 standard data are generated in operations. The preliminary trending analysis shows that the abrupt change in the data have been smoothed out and O-B bias, based on radiative transfer simulation using ECMWF forecast data, are decreased. In the current version of ATMS reprocessing data sets, reflector emissivity correction term has not been applied, which will be included in the next round of reprocessing activity.