2010-05-29: The impact of broken and inhomogeneous clouds on the retrieval of effective radius and cloud phase
Retrievals performed with the Cloud Physical Properties (CPP) algorithm at high (1 × 1 km2) and low (3 × 3 km2) resolution MODIS-observed 0.6-µm and 1.6-µm reflectances indicate that low-resolution re is overestimated by up to 5 µm and up to 2 µm relative to high-resolution re for broken clouds and inhomogeneous overcast clouds, respectively. For cloud phase, the fraction of water clouds is underestimated by about 2%. The re and cloud-phase retrievals are more affected over ocean than over land surfaces, because of the larger contrast between clouds and the underlying surface and hence a larger contribution from cloud-free parts to the observed reflectance at sub-pixel level. In the future, SEVIRI cloud property retrievals might benefit from a correction for broken cloudiness using the High Resolution Visible (HRV) channel.