Observations and models of irradiance profiles, column transmittance, and column reflectance during the Atmospheric Radiation Measurements Enhanced Shortwave Experiment

In the fall of 1995 the Atmospheric Radiation Measurement Enhanced Shortwave Experiment (ARESE) was conducted to address fundamental questions about the amount of absorption of solar radiation occurring in clear and cloudy skies. Irradiances measured from instruments flown on stacked aircraft as part of this experiment are compared to modeled irradiances for several representative days. As a basic check of the data and the model, the downwelling irradiances at 13 km are examined and found to be in good agreement, with both model and observations showing day-to-day variations as well as shorter timescale variations due to changing atmospheric conditions. Evidence of cloud-induced enhanced absorption is seen from an analysis of column reflectance and absorptance as determined from simultaneous measurements made from the stacked aircraft. When compared to model results, profiles of irradiance versus altitude as measured by one aircraft indicate cloud-induced enhanced absorption as well.