Polarimetric remote sensing of droplet distribution parameters from the UMBC-LACO imaging polarimeter during VOCALS-REx

The UMBC-LACO/GSFC Rainbow imaging polarimeter was flown repeatedly in October-November 2008, as part of the VOCALS-REx field campaign in Chile, aboard the CIRPAS Twin-Otter aircraft. Mounted in the CIRPAS Twin-Otter dropsonde bay, the Rainbow polarimeter was active on 18 flights out to the Point Alpha observation point (20S, 72W), mostly over stratiform clouds. The primary objective for the rainbow polarimeter was to image cloudbow phenomena to retrieve effective radii and widths for the cloudtop droplet distributions. The CIRPAS Twin Otter also had several instruments for the in situ measurement of the droplet distribution. Flight patterns usually included an over flight above the top of the cloud layers, several legs for in situ sampling of cloud droplets, and a last leg for cloud bow measurements overflying the cloud deck. Here we will present the first results of the cloud droplet size distribution measurements from the rainbow polarimeter in comparison with in situ and satellite remote sensing of the same clouds.