The National Oceanic and Atmospheric Administration (NOAA-21) Visible Infrared Imaging Radiometer Suite (VIIRS) NASA Level-2 (L2) Cloud Mask (VIIRS/NOAA21 Cloud Mask and Spectral Test Results 6-Min L2 Swath 750m) product is one of four continuity products designed to sustain the long-term records of both Moderate Resolution Imaging Spectroradiometer (MODIS) and VIIRS heritages. CLDMSK_L2_VIIRS_NOAA21 is the short-name for the NOAA-21 VIIRS incarnation of the Cloud Mask continuity product derived from the MODIS-VIIRS cloud mask (MVCM) algorithm, which itself is based on the MODIS (MOD35) algorithm. The MVCM describes a continuity algorithm that is central to both MODIS data (from Terra and Aqua missions) and VIIRS data (from Suomi National Polar-orbiting Partnership (SNPP) and Joint Polar Satellite System missions). Please bear in mind that the term MVCM does not appear as an attribute within the product’s metadata. Implemented to consistently handle MODIS and VIIRS inputs, the NOAA-21 VIIRS collection-1 products use calibration-adjusted NASA VIIRS L1B as inputs. The nominal spatial resolution of the NOAA-21 VIIRS L2 Cloud mask is 750 meters. The L2 netCDF product is acquired and processed every 6 minutes.For more information consult Product Page at: https://cimss.ssec.wisc.edu/MVCM/