CLOUD DROPLET EFFECTIVE RADIUS FROM SPACEBORNE POLARIZATION MEASUREMENTS

The spaceborne POLDER instrument provided the first quantitative measu rements of the Earth reflectance polarization characteristics. Many PO LDER images of polarized light show cloudbow type features over cloud fields for scattering angles between 150 and 170 degrees. This unexpec ted observation is attributed to the polarized radiance generated by s ingle scattering by cloud droplets. It shows that, in many cases, the cloud droplet size distribution is very narrow. The multidirectional p olarized radiance measurements can be inverted for an accurate estimat e of the cloud droplet radius.