Challenges and Progress in Extending the NASA EOS Imager Cloud Climate Data Record from MODIS to VIIRS

The Suomi NPP and JPSS-1 VIIRS imagers provide an opportunity to extend the NASA EOS MODIS Terra (18+ year) and Aqua (16+ year) cloud climate data record into the next generation operational era. However, building long-term cloud data records has been challenging for the two MODIS sensors alone due, in part, to instrument radiometric changes that can alias into data record trend studies. Further, the transition to the NOAA operational imagers on SNPP and JPSS-1/NOAA-20 is made difficult by VIIRS lack of key water vapor and CO₂ absorbing channels used by MODIS for high cloud detection and cloud-top property retrievals, in addition to a significant mismatch in the spectral location of the 2.2μm shortwave-infrared channels on MODIS and VIIRS that are used for cloud optical/microphysical retrievals and cloud thermodynamic phase. Moreover, differences in sensor sampling between MODIS and VIIRS, including spatial resolution and, to a certain extent, local observation time differences, pose additional challenges. We will summarize progress towards merging the NASA MODIS observational record with VIIRS to generate cloud optical property climate data record continuity across the observing systems using a common algorithm approach for reducing the impact of inherently different imager information content. We will also discuss initial assessments of the first public release of the NASA MODIS and VIIRS cloud climate data products.