An Exploration of 3-D Radiative Effects on Polarimetric Cloud Microphysical Retrievals: Results from idealized case studies and an LES satellite simulator

Abstract:

Case studies of 3-D polarized radiative effects and their influence on cloud microphysical retrievals are presented from two perspectives: The first focuses on idealized cloud cases, isolating simplified examples of the impact of horizontal photon transfer. The second examines clouds under more realistic inhomogeneous conditions by analyzing 3-D effects observed in a bounded-cascade fractal cloud model as well as an LES cloud model. Within this study, we generate radiances using the 3-D polarized Monte Carlo code 3DMCPOL [Cornet et al., 2010] and the NASA GISS 1-D Polarized Doubling-Adding (PDA) code [de Haan et al., 1987]. Comparisons between the 1-D and 3-D radiances and retrievals will be made in order to study various impacts and retrieval biases. Specifically, we directly examine 3-D effects influencing radiance (i.e. shadowing/illuminating effects, photon transport out of cloud edge), as well as the impact of optical and microphysical inhomogeneity on 3-D polarimetric retrievals. One area we will address specifically is how 3-D radiative effects impact polarimetric retrievals near cloud edges. Additionally, we examine the practical implications of retrieval resolution and cloud top height. The relevance of these results for the analysis of data from future satellite polarimetric cloud remote sensing missions, such as NASA’s PACE mission, or ESA’s 3MI mission, will be discussed briefly.