Evaluation of Total Precipitable Water Trends from MiRS Reprocessed SNPP ATMS Observations

The NOAA’s Microwave Integrated Retrieval System (MiRS) is an operational microwave-only satellite retrieval system. MiRS retrieval products from the Advanced Technology Microwave Sounder (ATMS) on board of Suomi National Polar-orbiting Partnership (SNPP) have been available since 2012. It is worth noting that the latest ATMS sensor calibration algorithm for SNPP Level 1 data has been applied operationally since 10/15/2019. Additionally, the MiRS retrieval algorithm has seen several updates featuring science improvements since the launch of SNPP. In order to provide consistent retrieval products with application for climate studies, we have reprocessed SNPP ATMS using both the updated sensor calibration algorithm and a consistent up to date version of MiRS for all data between 2012 to 2020.

The SNPP ATMS sounder provides information such as temperature and water vapor in the atmosphere. In this presentation, we focus on Total Precipitable Water (TPW) trend analysis. TPW is an important climate variable as it is a key element of the hydrological cycle and is responsive to changes in global climate related to greenhouse gas-induced warming. TPW from reprocessed SNPP ATMS retrievals are compared with ERA5, or the fifth European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis. Preliminary results show that the global TPW trend from reprocessed SNPP ATMS is 0.33 mm/decade, while the trend from EAR5 is 0.16 mm/decade. We also found that the TPW trend is not uniformly distributed spatially. However, the spatial patterns are similar between SNPP ATMS retrievals and the ERA5 despite of the trend value difference between this two data source. Further analysis is ongoing and insights into similarities and differences in the global and regional trends will be presented.