Absorption of solar radiation by the cloudy atmosphere: Further interpretations of collocated aircraft measurements

We have extended the interpretations made in two prior studies of the aircr aft shortwave radiation measurements that were obtained as part of the Atmo spheric Radiation Measurements (ARM) Enhanced Shortwave Experiment (ARESE). These extended interpretations use the 500 nm (10 nm bandwidth) measuremen ts to minimize sampling errors in the broadband measurements. It is indicat ed that the clouds present during this experiment absorb more shortwave rad iation than predicted by clear skies and thus by theoretical models, that a t least some (less than or equal to 20%) of this enhanced cloud absorption occurs at wavelengths <680 nm, and that the observed cloud absorption does not appear to be an artifact of sampling errors nor of instrument calibrati on errors.