Cloud Properties from MODIS and VIIRS for CERES: Intercomparison and
Validation with CALIOP
Abstract
The Clouds and the Earth’s Radiant Energy System (CERES) project
monitors Earth’s long-term energy balance and produces data products
which have improved our understanding of the role clouds and aerosols
play in that balance. Cloud property retrievals from the Moderate
Resolution Imaging Spectroradiometer (MODIS) and the Visible Infrared
Imaging Radiometer Suite (VIIRS) are a major component of many of these
data products. It is important for cloud property retrievals to be
consistent over the course of the record so that artificial
discontinuities are not introduced into the Earth radiation budget
record. In practice, the MODIS and VIIRS instruments have different
characteristics and different sets of spectral bands so deriving
completely consistent cloud properties from the two instruments is a
complex task. This paper investigates differences in the cloud
properties retrieved from MODIS and VIIRS using the Cloud-Aerosol Lidar
with Orthogonal Polarization (CALIOP) instrument as an independent
validation source. Particular consideration is given to CALIOP’s
sensitivity to optically thin clouds and the effect these clouds have on
the retrieved cloud properties, especially cloud thermodynamic phase.
Differences in cloud phase and cloud optical depth from MODIS and VIIRS
are characterized by different cloud types including multi-layer
scenarios. Characterizing these retrieval differences will help
understand and mitigate artifacts in the long-term record.