HR: 1340h
AN: A43D-0132    [Abstracts]
TI: Top-of-Atmosphere Cloud Radiative Effect Estimated from CERES Data Set
AU: * Kato, S
EM: s.kato@larc.nasa.gov
AF: Hampton University, Mail Stop 420 NASA Langley Research Center, Hampton, VA 23681-2199 United States
AU: Loeb, N G
EM: n.g.loeb@larc.nasa.gov
AF: Hampton University, Mail Stop 420 NASA Langley Research Center, Hampton, VA 23681-2199 United States
AB: The error in estimating top-of-atmosphere irradiance from radiances measured by CERES instruments is expected to be smaller than the error in ERBE derived top-of-atmosphere irradiance because scene identification is done at a smaller scale than the CERES footprint size. Cloud and aerosol properties derived from MODIS narrowband radiances, which have a 1 km resolution, are collocated with CERES footprints. In addition, the SSM/I derived snow and sea ice fraction is also collocated with CERES footprints. Because of these detailed information of cloud and aerosol properties and snow and sea ice fractions within a CERES footprint, angular distribution models that provide the irradiance from the measured radiance are built by many scene types. The improvement of the irradiance estimate is expected to be large over polar regions where ERBE had a known problem of distinguishing clouds from bright snow and sea ice. Because of cloud properties and sea ice fraction collocated with CERES footprints, we are also able to estimate the top-of-atmosphere cloud radiative effect in shortwave and longwave regions as a function of sea ice fraction. As reported by Curry and Ebert (1992), the top-of-atmosphere NET cloud radiative effect is dominated by the shortwave effect during summer time. It is also large when sea ice fraction is small. A preliminary result indicates that the NET cloud radiative effect averaged over a day changes from approximately -20 W m^-2 to less than -100 W m^-2 when sea ice fraction changes from 1 to 0. Seasonal variations and inter-annual variations of the cloud radiative effect are also discussed.
DE: 0321 Cloud/radiation interaction
DE: 0360 Radiation: transmission and scattering
DE: 0750 Sea ice (4540)
DE: 0758 Remote sensing
DE: 0764 Energy balance
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005