IN-SITU MEASUREMENTS OF THE SCATTERING PHASE FUNCTION OF STRATOCUMULUS, CONTRAILS AND CIRRUS

Original measurements were obtained in stratocumulus, contrails and ci rrus clouds by using a new optical airborne probe, the 'Polar Nephelom eter', which is the first airborne instrument to make direct in situ m easurements of the scattering phase function of cloud particles over a broad range of sizes (from a few micrometers to about 500 mu m diamet er). Preliminary measurements show that in stratocumulus water droplet cloud, the measured phase function fits very well with the phase func tion derived from direct PMS probes measurements. This definitively co nfirms the reliability of the Polar Nephelometer for airborne measurem ents. In contrails and natural cirrus, measured scattering phase funct ion indicates major differences with those used in cloud models which assume ice spheres or simple geometric shape of ice particles. These r esults highlight new potential insights on both modelling of climate p rocesses and methodologies for cloud remote sensing from satellite mea surements.