[A-AS15] ミクロスケール気象の稠密観測・数値モデリングの新展開

[AAS15-P04] Polarimetric Observations of Precipitating and Non-precipitating Stratiform Clouds

*Kenneth Allan Sinclair¹ (1.NASA Goddard Institute for Space Studies)

キーワード：Polarization, Precipitation, Clouds, Remote Sensing, Rainbow Fourier transform

We present an analysis using polarimetric observations of precipitating clouds. Polarized reflectances originate from single scattering events near cloud top are nearly unaffected by multiple scattering within a cloud. These polarized reflectances as a function scattering angle in the rainbow angular range and droplet radius are integral transforms, allowing the shape of the droplet size distribution to be retrieved without a priori knowledge. Studies of droplet size distribution variability have remained challenging because observational studies have traditionally been limited to in situ measurements made by cloud probes on aircraft while profiling clouds. These studies focusing on how dispersion varies with other cloud properties, aerosols and atmospheric state parameters have yielded contradicting results.

We present observations from NASA’s Research Scanning Polarimeter (RSP) during the NASA-led Observations of Aerosols Above Clouds and their Interactions (ORALCES) campaign. We present the summary of a study investigating variability between cloud properties and precipitation. Precipitation rates using in this study are measured by the Advanced Precipitation Radar, which was flown alongside the RSP during ORACLES. We observe a broad or bimodal feature in the droplet size distribution is commonly observed in the most strongly precipitating cases indicating that precipitating and non-precipitating clouds can be discerned using polarimetric observations from near cloud-top.