Observations and calculations of radiative properties of clouds observed during RACE

The absorption and albedo of low, thin, marine stratus clouds are investigated using data collected by two aircraft during the Radiation, Aerosol and Cloud Experiment, conducted off the coast of Nova Scotia, Canada. Measured values of absorption and albedo are compared to calculations using a plane parallel radiative transfer model and drop size distributions determined from cloud profiles conducted close in time to the radiation measurements. The calculated values of albedo and absorption were consistent with the measurements. Uncertainties in absorption measurements due to instrument error were high. The model is used to determine cloud susceptibility, the sensitivity of cloud albedo to changes in droplet concentration. The susceptibilities determined from these calculations agree well with previous studies. The measured changes in albedo are consistent with those predicted by the model