Using Radio Occultation observations to detect ATMS brightness temperature bias
Presenter:
Bin Zhang
CISESS/ESSIC, University of Maryland, College Park, MD, USA
NOAA/STAR, College Park, MD, USA; Department of Astronomy, University of Maryland, College Park, MD, USA; NOAA/STAR, College Park, MD, USA
Poster
Radio Occultation (RO) utilizes the LEO satellite measurements of the GNSS signal path delay to perform inversion of the atmospheric temperature profiles. The GNSS RO-derived bending angle data have been used in operational Numerical Weather Prediction (NWP) models to correct temperature bias. The long-term stability of RO temperature profile retrievals makes them ideal datasets for climate study. RO observations have been used to correct the inter-satellite radiometric bias and brightness temperature jumps due to calibration algorithm changes for Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit (AMSU) measurements to construct climate data records. The Advanced Technology Microwave Sounder (ATMS) onboard JPSS satellites SNPP and NOAA-20 profile atmosphere temperature and moisture. There has been a few updates in the calibration algorithm of operational ATMS data production. To maintain long term consistency, the SNPP ATMS data were reprocessed with consistent calibration algorithm by NOAA/STAR. With the recent release of reprocessed RO CDR/ICDR dataset for multiple RO missions by ROM SAF, we have an opportunity to carry out inter-comparison between the reprocessed RO data and the reprocessed/operational ATMS data. We carry out collocation analysis between the GPS RO observations and ATMS observations, and use CRTM to model the ATMS channels brightness temperature from the RO wet temperature profiles. In this study, the ATMS channel 10 will be used to characterize the lower stratosphere temperature. The mean bias and trend of the brightness temperature difference between the CRTM simulation using RO data and SNPP ATMS observation will be evaluated. NOAA-20 ATMS data are analyzed similarly to derive the bias between SNPP and NOAA-20 ATMS. Comparison between RO and ATMS observation can help extend the long term CDR of microwave observations from AMSU to ATMS.
Poster in PDF:
