IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing (Jan 2020)
Evaluation of NOAA-20 VIIRS Reflective Solar Bands Early On-Orbit Performance Using Daily Deep Convective Clouds Recent Improvements
Abstract
The visible infrared imaging radiometer suite (VIIRS) onboard the National Oceanic and Atmospheric Administration - 20 (NOAA-20) satellite was successfully launched in November 2017. During the NOAA-20 VIIRS postlaunch test [(PLT) or extensive cal/val, launch-April 30, 2018], a daily deep convective cloud (DCC) method was developed to support the timely decision making of reflective solar bands (RSBs) on-orbit calibration updates. Different from its predecessor, the VIIRS onboard the Suomi National Polar-Orbiting Partnership (S-NPP) satellite, NOAA-20 VIIRS RSBs have been calibrated using constant calibration factors since April 27, 2018, with the assumption that no significant instrument responsivity change occurs. In this study, the daily DCC method was further refined for evaluating NOAA-20 VIIRS RSB performance after two years on-orbit. An annual cycle climatology for DCC was developed to reduce uncertainty in the trend analysis. NOAA-20 VIIRS observations during the PLT were reprocessed to generate consistent data records. Two-year trends (January 6, 2018-January 5, 2020) were analyzed using consolidated (reprocessed + operational) NOAA-20 daily DCC time series and compared with S-NPP. NOAA-20 daily DCC time series for the visible and near-infrared bands shows small upward trends (up to 0.4%/year in M1), while no significant trend was observed in S-NPP. Moreover, NOAA-20 I3 and M10 exhibit larger than the expected interchannel inconsistency (~1.2%) compared with S-NPP. NOAA-20 RSBs are biased ~1.5%-4.5% lower than S-NPP, generally consistent with results from other methods.
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