Preliminary Comparison of Backus Gilbert and AAPP Remapped ATMS Bias Monitoring Using JCSDA CRTM

Li Bi 1 Ninghai Sun 1 Fuzhong Weng 1 1 NOAA/NESDIS/Satellite Applications and Research (STAR)

IntroductionThe Cross-track Infrared and Microwave Sounding Suite (CrIMSS), consisting of the Cross-track Infrared Sounder (CrIS) and the first space-based, Nyquist-sampled cross-track microwave sounder, the Advanced Technology Microwave Sounder (ATMS), will provide atmospheric vertical profile information needed to improve numerical weather and climate modeling. Recently a near real-time bias monitoring system for the ATMS has developed in Center for Satellite Applications and Research (STAR). We simulate the brightness temperatures at 22 channels over oceans corresponding to each ATMS beam position and compare the simulated results with the measurements. The radiative transfer modeling used in this study is the JCSDA Community Radiative Transfer Model (CRTM). CRTM simulation is performed under clear atmospheric conditions over ocean using sea surface temperature (SST), wind vector, and temperature/moisture profiles obtained from the ECMWF analysis. The ATOVS and AVHRR Processing Package (AAPP) is developed and maintained by the EUMETSAT Satellite Application Facility (SAF). It is extended to accept NPP data during 2011 (ATMS and CrIS) with additional functionality including manipulation of ATMS beam and remapping of manipulated ATMS to CrIS footprints. In this study, ATMS remapped TDRs from Backus Gilbert (BG) method and AAPP package were evaluated using golden day data (02/25/2012). Different statistical approached were performed for selected pairs as well. Bias characteristics of these two products are evaluated using JCSDA CRTM. O-B statistic analysis are performed.

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BG Remapped ATMS

AAPP Remapped ATMS

BG Remapped ATMS

AAPP Remapped ATMS

BG Remapped ATMS

AAPP Remapped ATMS

• Histograms of selected BG remapped ATMS and AAPP remapped ATMS SDRs show similar patterns. • BG-Sim bias and AAPP-Sim bias show different histogram patterns

BG vs. AAPP histogram BG-SIM bias vs. AAPP-SIM bias

The spread in the scatter distributions is small for high altitude sounding channel.

BG remapped ATMS vs. CRTM Simulation AAPP remapped ATMS vs. CRTM Simulation

ATMS TDR Bias O-B at Each Channel

• Over ocean (55 ON ~ 55 OS)

• Clear sky

• Ascend/Descend separated

ATMS TDR Angular Dependent Bias O-B at Each FOV

• Over ocean (55 ON ~ 55 OS)

• Clear sky

• Ascend/Descend separated

Evaluation Methods

• ATMS to be mapped to each of the CrIS 9 FOVs

• The orientation of the 9 FOVs rotates across the scan

• Use the supplied lat/lon to identify the neighboring ATMS samples for each CrIS FOR

• Use bilinear interpolation for the individual CrIS FOVs

http://research.metoffice.gov.uk/research/interproj/nwpsaf/aapp/NWPSAF-MO-UD-027_ATMS_CrIS.pdf