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 aircraft shortwave radiation measurements that were obtained as part of the Atmospheric Radiation Measurements (ARM) Enhanced Shortwave Experiment (ARESE). These extended interpretations use the 500 nm (10 nm bandwidth) measurements to minimize sampling errors in the broadband measurements. It is indicated that the clouds present during this experiment absorb more shortwave radiation than predicted by clear skies and thus by theoretical models, that at least some (≤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 calibration errors.