干旱区生态环境知识资源中心

We update the effort in the radiometric evaluation of the two different versions of the calibrated sensor data records (SDRs) for the SNPP VIIRS reflective solar bands (RSBs) through direct comparison analysis with Aqua MODIS. The two SDR versions of interest are the official version generated by the Interface Data Process Segment (IDPS) system and the independent version calibrated by the NOAA Ocean Color (OC) Team. The key finding is the continual drift in the IDPS-generated radiance data for five short-wavelength RSBs (443 nm to 1238 nm), contrasting the multi-year stable result for the OC version. SNPP VIIRS M1 (410 nm) versus Aqua MODIS B8 (412 nm) continues to show drift for the IDPS-based and the OC-based comparison time series, pointing to the continual and worsening inaccuracy in Aqua MODIS B8 radiometric data that had been established by preceding studies in the previous year. The SNPP VIIRS M7 (862 nm) versus Aqua MODIS B2 (859 nm) comparison exhibits recent discontinuity in both IDPS-based and OC-based time series - the discontinuity for IDPS-generated SNPP VIIRS M7 is estimated at 0.5% upward near early October 2016, and for Aqua MODIS B2 it is 1.7% upward near mid-July 2016. The other important first-time result is the SNPP VIIRS M11 (2257 nm) versus Aqua MODIS B7 (2130 nm) comparison time series using the land-based snowy scenes of Antarctica, which demonstrates multi-year stability of SNPP VIIRS M11 and the agreement between the IDPS and the OC version of the VIIRS SDRs at this spectral range.