A211-0008
A Combined Lidar-Polarimeter Inversion Approach for Aerosol Remote Sensing over Ocean

Wednesday, 16 December 2020
Poster
Feng Xu1, Lan Gao2, Jens Redemann3, Connor Flynn4, Reed Espinosa5, Arlindo daSilva6, Snorre Stamnes7, Sharon P Burton7, Richard Anthony Ferrare7, Brian Cairns8 and Oleg Dubovik9, (1)University of Oklahoma Norman Campus, School of Meteorology, Norman, OK, United States, (2)Desert Research Institute Reno, Reno, NV, United States, (3)University of Oklahoma, School of Meteorology, Norman, OK, United States, (4)University of Oklahoma Norman Campus, Norman, United States, (5)University of Maryland Baltimore County, Physics, Baltimore, MD, United States, (6)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (7)NASA Langley Research Center, Hampton, VA, United States, (8)NASA Goddard Institute for Space Studies, New York, NY, United States, (9)Laboratoire d'Optique Atmosphérique, CNRS/University of Lille, Lille, France
Abstract:
An optimization algorithm is developed to retrieve the vertical profiles of aerosol concentration, refractive index and size distribution, as well as a set of ocean surface reflection properties. The retrieval uses a combined set of lidar and polarimeter measurements. The former includes extinction, backscatter, and/or depolarization, while the latter includes radiance (L) and polarimetric components (Q/L and U/L). To gain retrieval flexibility, efficiency and stability, our inversion includes (1) a hybrid radiative transfer model that combines the computational strengths of the Markov-chain and adding-doubling approaches in modeling polarized RT in vertically inhomogeneous and homogeneous media, respectively; (2) a bio-optical model that represents the water-leaving radiance of an open ocean with a single term – chlorophyll-a concentration; (3) extra constraints regarding the smooth variations of several aerosol properties with altitude; and (4) an optimization scheme that adjusts the aerosol and surface properties in an iterative way to fit observations. We tested the retrieval using 51 sets of coincident Lidar and polarimetric data acquired during NASA’s ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) field campaign in the Southeast Atlantic Ocean under clear sky conditions. The lidar measurements were performed by NASA Langley’s airborne High Spectral Resolution Lidar 2 (HSRL-2). The polarimetric measurements were performed by the Research Scanning Polarimeter developed at NASA GISS. As validation, the aerosol retrieved optical depth (AOD) above aircraft and extinction profile are compared to the reference data from NASA Ames airborne Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) and HSRL-2 measurements, respectively. The retrieved vertical profiles of single scattering albedo and microphysical properties are compared to the reference data measured by the instrumentation suite of Hawaii Group for Environmental Aerosol Research (HiGEAR, University of Hawaii).
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