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Use of High Spectral Resolution Infrared Sounders to Validate Reanalyses. Mitch Goldberg, Likun Wang NOAA/NESDIS/STAR Satellite Meteorology and Climatology Division. Motivation.
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Use of High Spectral Resolution Infrared Sounders to Validate Reanalyses Mitch Goldberg, Likun Wang NOAA/NESDIS/STAR Satellite Meteorology and Climatology Division
Motivation Many studies comparing AIRS, IASI and aircraft interferometer have demonstrated the accuracy and stability of AIRS and IASI. Finally we have a very precise, accurate reference dataset to validate other datasets, such as radiosondes, model analyses, reanalyses, etc. Unlike GPS RO, the thermal infrared radiances are influenced by key essential climate variables: CO2, CH4, O3, CO, Clouds, Aerosols, Temperature, Moisture. CLARREO mission is design to meet this objective, with onboard SI traceability. Climate Reanalyses are gaining recognition for providing historical climate information but each are different, why??
Wide spread in Projections Need to improve model projections. With benchmark – reference satellite observations, we can insist that the models agree with the satellite observations
Approach • Simulate AIRS IR radiances from Reanalyses and compare with observed AIRS. • Limiting factors: • How good is AIRS? • How good is the radiative transfer model?
Double Difference versus SNOs SNOs Polar Regions 1) Indirect vs. Direct comparison 2) Warm scenes vs. cold scenes Task140 Brief Four channels
Results 6.5µm IASI-AIRS 10.7µm Zero line 12.0µm SNO North SNO South Double Difference GOES-AIRS GOES-IASI 13.3µm Task140 Brief Wang et al. 2010, manuscript for GRL
Water vapor channel 300 mb peak DR = f( DT, DQ) Increasing negative means increase in water vapor
Comparison with TWP ARM Site - Night time – September 2002-2005 N=22
Summary Datasets have been generated for 5 years data from January 2003:
Summary/Recommendations • AIRS and IASI are reference quality instruments which can be used to validate climate reanalyses and climate projections. • Need to continue to improve radiative transfer models via better laboratory spectroscopy and ground truth data (e.g. GRUAN) • Absolute observations and radiative transfer will allow measurements to be used as anchor points and will allow focus on improving model physics.
ERA Interim Reanalysis - ECMWF Weather Analysis – September 2004
ERA Interim Reanalysis - ECMWF Weather Analysis Sept. 2007 ECMWF 2003 – 2005 can be used to validate reanalyses
JRA25 vs ECMWF and ERA Interim (above 500 mb) ERAIM - JRA25 ECMWF - JRA25