Establish Operational Earth Observation Data Continuity Using VIIRS and METimage

AVHRR series of instruments have been providing Earth observation data for multiple decades that have immensely benefited in weather prediction and climate monitoring. The launch of VIIRS instruments onboard SNPP and NOAA-20 has replaced the AVHRR in the afternoon orbit. Similarly, the METtimage onboard EPS-SG that is scheduled to launch around 2022 to provide the operational Earth observations will replace AVHRR in the morning orbit. METimage is designed with advanced capability compared to AVHRR in terms of spatial, spectral and temporal coverage. The long term data continuity with AVHRR needs to be established using VIIRS and future MetImage instruments. However, the VIIRS and the MetImage instruments are not identical and thus their capabilities and features need to be compared and evaluated. This study focuses on analyzing the similarities and differences between VIIRS and METimage in the radiometric, spectral and spatial domain. The possible impacts on the EDR products will also be discussed. For example, METimage has water vapor channels which VIIRS does not have; VIIRS has dual gain ocean color channels with three blue bands whereas METimage has only one blue band (0.443 um) and thus the impacts on the ocean color products retrieval and aerosol retrieval need to be evaluated; METimage does not have Day/Night Band; METimage has two MWIR fire detection channels and thus needs to evaluate fire detection capability and improvements in fire radiative power, but saturation may become a concern. Besides, the acquisition time and spatial resolution of METimage data are different from VIIRS. The study attempts to provide comparisons to the user community on the instrument level differences that need to be understood well to evaluate the impacts on EDR products and establish accurate and reliable data continuity among VIIRS, METimage, and AVHRR.