Cloud Energy Management
The role of fractional area coverage by cloud types in the
energy balance of the earth is investigated through joint use of
International Satellite Cloud Climatology Project (ISCCP) C1 cloud data
and Earth Radiation Budget Experiment (ERBE) broadband energy flux data
for the one-year period March 1985 through February 1986. Multiple
linear regression is used to relate the radiation budget data to the
cloud data. Comparing cloud forcing estimates obtained from the
ISCCP-ERBE regression with those derived from the ERBE scene
identification shows generally good agreement except over snow, in
tropical convective regions, and in regions that are either nearly
cloudless or always overcast. It is suggested that a substantial
fraction of the disagreement in longwave cloud forcing in tropical
convective regions is associated with the fact that the ERBE scene
identification does not take into account variations in
upper-tropospheric water vapor. On a global average basis, low clouds
make the largest contribution to the net energy balance of the earth,
because they cover such a large area and because their albedo effect
dominates their effect on emitted thermal radiation. High, optically
thick clouds can also very effectively reduce the energy balance,
however, because their very high albedos overcome their low emission
temperatures.
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