CERES
PROGRAMMABLE
AZIMUTH
PLANE
SCANS
The Clouds and the Earth's Radiant Energy System (CERES) instrument is a narrow
field-of-view scanning radiometer; its scan plane can be rotated in azimuth
from -90 to +90 deg with respect to the satellite orbit plane. Cross-track
scanning, perpendicular to the orbit plane, provides the largest possible
spatial coverage; but each target is viewed once, at a single angle, per
overpass. Along-track scanning, in the orbit plane, allows a target to be
observed several times per orbit under a range of viewing angles; but the
spatial coverage is limited to a narrow swath around the sub-satellite track.
The rotating azimuth capability of the CERES instrument has been used primarily
to sample the anisotropic radiance field from all directions. This capability
can be used to enhance our ability to intercalibrate instruments on different
spacecraft and to augment the spatial and angular coverage of targeted areas
during intensive observation field campaigns.
