Available from UMI in association with The British Library. Requires signed TDF. Since the presence of clouds greatly modifies the overall distribution of radiative heating and cooling in the troposphere, it is of considerable importance to understand and to be able to model radiative transfer by clouds. The development and testing of a multilayer cloud model is described. This model is based on the matrix operator algorithm and treats clouds as being plane parallel, composed of a number of horizontal, homogeneous layers, which allows for vertical variations in the cloud structure. The model calculates the upward and downward flowing radiances at the top and base of the cloud, and at the boundaries between the sub-cloud layers, as a function of zenith angle. Scattering, absorption and emission by the cloud droplets are accounted for within the model, and correction terms are applied for gaseous absorption both within the cloud and in the atmosphere. A multichannel infrared radiometer is described, which can make measurements of radiation in sixteen discrete narrow-band spectral intervals. This instrument has been modified so that its field of view can be directed to the zenith, nadir and at angles of 15^circ , 30^circ, 45 ^circ and 60^circ to the nadir. Results are reported from a flight using the Meteorological Research Flight's Hercules aircraft, to study stratus cloud over the North Sea. The multichannel radiometer was mounted inside the port wing pod of the aircraft, and simultaneous measurements were made of the cloud microphysics. These data were used to calculate the single scattering phase functions for the various-cloud layers, and the results were used as input data to the cloud model, together with the temperature profile. The output from the cloud model is compared with the experimental results: discrepancies are attributed to the variability of the cloud, and alternative model clouds suggested which agree more closely with the measured radiances.
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- Physics: Astronomy and Astrophysics