The Influence of Spatial Resolution on the Inference of Ice Cloud Particle Morphological Parameters from Multi-angle Satellite Observations

Recent studies suggest that choosing an adequate ice particle habit and roughness for single scattering calculation improves the spectral consistency of retrieved optical thickness values between visible/near-infrared retrievals and thermal infrared retrievals. The selection of a representative particle habit and roughness parameter is often based on satellite observations by multi-angle sensors such as the Multi-angle Imaging Spectroradiometer (MISR) and the Polarization and Directionality of the Earth's Reflectances (POLDER). However, multi-angle observations, especially intensity-only observations, are sensitive to sub-pixel cloud heterogeneity and cloud 3-d effects, and their effect on the habit and roughness inference is not yet evaluated. In this presentation, we demonstrate to what extent the heterogeneity affects the inference, focusing on sub-pixel horizontal heterogeneity. High-resolution ice cloud images (275m at nadir) from the MISR are averaged at multiple spatial scales (up to 6km, which is the POLDER nadir resolution), and the particle roughness is inferred on the pixel-by-pixel basis. Both results from synthetic and real data will be presented with stratification by viewing zenith angles.