https://hal-insu.archives-ouvertes.fr/insu-03686259Emde, ClaudiaClaudiaEmdeBarlakas, VasileiosVasileiosBarlakasCornet, CélineCélineCornetLOA - Laboratoire d’Optique Atmosphérique - UMR 8518 - INSU - CNRS - Institut national des sciences de l'Univers - Université de Lille - CNRS - Centre National de la Recherche ScientifiqueEvans, FrankFrankEvansWang, ZhenZhenWangLabonotte, Laurent C.Laurent C.LabonotteLOA - Laboratoire d’Optique Atmosphérique - UMR 8518 - INSU - CNRS - Institut national des sciences de l'Univers - Université de Lille - CNRS - Centre National de la Recherche ScientifiqueMacke, AndreasAndreasMackeMayer, BernhardBernhardMayerWendisch, ManfredManfredWendischIPRT polarized radiative transfer model intercomparison project - Three-dimensional test cases (phase B)HAL CCSD20183D radiative transferPolarizationModel intercomparisonBenchmark resultsAstrophysics - Earth and Planetary AstrophysicsPhysics - Atmospheric and Oceanic Physics[SDU] Sciences of the Universe [physics]POTHIER, Nathalie2022-06-02 15:42:452023-03-24 14:53:272022-06-02 15:42:45enJournal articles10.1016/j.jqsrt.2018.01.0241Initially unpolarized solar radiation becomes polarized by scattering in the Earth's atmosphere. In particular molecular scattering (Rayleigh scattering) polarizes electromagnetic radiation, but also scattering of radiation at aerosols, cloud droplets (Mie scattering) and ice crystals polarizes. Each atmospheric constituent produces a characteristic polarization signal, thus spectro-polarimetric measurements are frequently employed for remote sensing of aerosol and cloud properties. <P />Retrieval algorithms require efficient radiative transfer models. Usually, these apply the plane-parallel approximation (PPA), assuming that the atmosphere consists of horizontally homogeneous layers. This allows to solve the vector radiative transfer equation (VRTE) efficiently. For remote sensing applications, the radiance is considered constant over the instantaneous field-of-view of the instrument and each sensor element is treated independently in plane-parallel approximation, neglecting horizontal radiation transport between adjacent pixels (Independent Pixel Approximation, IPA). In order to estimate the errors due to the IPA approximation, three-dimensional (3D) vector radiative transfer models are required. <P />So far, only a few such models exist. Therefore, the International Polarized Radiative Transfer (IPRT) working group of the International Radiation Commission (IRC) has initiated a model intercomparison project in order to provide benchmark results for polarized radiative transfer. The group has already performed an intercomparison for one-dimensional (1D) multi-layer test cases [phase A, 1]. This paper presents the continuation of the intercomparison project (phase B) for 2D and 3D test cases: a step cloud, a cubic cloud, and a more realistic scenario including a 3D cloud field generated by a Large Eddy Simulation (LES) model and typical background aerosols. <P />The commonly established benchmark results for 3D polarized radiative transfer are available at the IPRT website (http://www.meteo.physik.uni-muenchen.de/ iprt).