MODIS retrievals of cloud effective radius in marine stratocumulus exhibit no significant Bias

Past intercomparisons have found a significant bias toward larger remotely sensed re. Explanations for this bias have focused on retrieval algorithms and large-scale heterogeneity, with in situ measurement uncertainty regarded as a minor factor.

We compare Moderate Resolution Imaging Spectroradiometer re with in situ observations of marine stratocumulus clouds from three aircraft campaigns using a phase Doppler interferometer probe. Retrieved and in situ re typically agree within uncertainty in both nonprecipitating and drizzling conditions with no apparent systematic bias (mean bias of -0.22 mu m, mean relative bias 3%). Agreement depends on the choice of in situ probe as well as microphysical context.