The Intercomparison of Satellite-Derived and In Situ Profiles of Droplet Effective Radii in Marine Stratocumulus Clouds

It was found that the satellite spectral measurements can be used not only for the determination of cloud top effective radii but also for retrieving the effective radii vertical profile in some specific cases (e.g., for low marine stratocumulus clouds with negligible effects of horizontal variability). The inversion algorithm was applied to Moderate Resolution Imaging Spectroradiometer (MODIS) radiances (at the wavelengths of 0.865, 1.24, 1.6, and 2.1 μm), and the results were validated against in situ airborne measurements of cloud vertical profiles of the effective radius. We found that the results were more reliable for the cases with large vertical gradients of droplet sizes. The new retrieval method, based on the optimal estimation approach, enabled a higher accuracy of the liquid water path estimate than that produced with the standard MODIS vertically homogeneous algorithm.