Monitoring of IR Clear-Sky Radiances over Oceans for SST nearreal
time web-based system has been established in July 2008. It analyzes Model (Community Radiative Transfer Model,
CRTM) minus Observation (M-O) biases in clear-sky ocean brightness temperatures (BT) in AVHRR bands 3.7 (IR37),
11 (IR11), and 12μm (IR12) onboard NOAA-16, -17, -18, -19 and Metop-A. In January 2012, AVHRR-like bands of
VIIRS onboard the Suomi National Polar Partnership (S-NPP; launched in October 2012), and two MODIS instruments
onboard Terra and Aqua, were included in MICROS. Double-differences are employed to check various sensors for
radiometric consistency. The VIIRS and AVHRR have been in-family, and the consistency further improved after the
VIIRS IR calibration was fine-tuned on 7 March 2012. However, MODIS M-O biases have been out of family (by -0.6K
in IR 11, and -0.3K in IR12). Analyses have shown that these anomalies in MODIS M-O biases are caused by the "M"
term, i.e., incorrect MODIS transmittance coefficients in CRTM v2.02. Based on feedback from NESDIS SST and U.
Wisconsin Teams, CRTM Team updated transmittance coefficients in CRTM v2.10. As a result, MODIS M-O biases are
now in agreement with AVHRR/VIIRS. However, cross-platform Terra/Aqua bias of ~0.3 K in Ch20 (3.9μm) remains,
likely due to calibration uncertainties in MODIS L1b product. This paper documents the joint effort by the SST, MODIS
Characterization Support and CRTM Teams towards identifying and resolving observed cross-platform inconsistencies.