Challenges and Progress in Generating Multi-Instrument Imager Cloud Data Records from MODIS and VIIRS

The Suomi NPP and JPSS-1 VIIRS imagers provides an opportunity to extend the 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 MODIS alone due, in part, to instrument radiometric changes that can alias into data record trend studies. Further, in transitioning to the operational imagers, VIIRS lacks key water vapor and CO₂ absorbing channels used by MODIS for high cloud detection and cloud-top property retrievals. In addition, there is a significant mismatch in the spectral location of the 2.2 μm shortwave-infrared channels on MODIS and VIIRS that are used for cloud optical/microphysical retrievals and cloud thermodynamic phase.

We will discuss progress in stabilizing the MODIS radiometric record for Collection 6.1 reprocessing and show trend analyses demonstrating the impact on the MODIS Terra and Aqua cloud data records, including an assessment of ENSO contributions. We also summarize progress towards merging the 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 spectral information content.