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Event Time
3:30 p.m.
Atlantic Building Room 2400 & Zoom

AOSC Seminar by Dr. Oleg Dubovik, 8/18/2022

AOSC Seminar

Dr. Oleg Dubovik

Laboratoire d'Optique Atmosphérique, Université Lille, France


Title: The concept of universal retrieval algorithm for enhanced remote sensing of the atmosphere: GRASP-OPEN developments


The presentation discusses the possibility of development of universal retrieval algorithm for a variety of the atmospheric remote sensing applications. Indeed, practically any algorithm used for interpreting remote sensing observations of atmosphere relies on modeling interactions of the light with atmospheric gases, aerosol, clouds and underlying surface. Also, the algorithm should include some inversion development. Therefore, it is quite reasonable to expect that once a solid forward model for atmosphere radiation together with an inversion procedure are developed they can be reused for more than one application. Correspondingly, some efforts in development of new algorithm can reduced and, more importantly, the development and usage of a single algorithm for multiple applications evidently leads in continuous improvements and validations of both forward model and inversion procedure.  The recently developed GRASP (Generalized Retrieval of Aerosol and Surface Properties) approach is as an example of such universal algorithm.

GRASP retrieves the properties of both aerosol and land surface from diverse remote sensing observations (Dubovik et al. 2011, 2021). The algorithm is based on several fundamental principles. First, GRASP relies on complete and rigorous modeling of atmospheric radiation. According to GRASP design any parameter used in forward model can be considered as the retrieved one in every remote sensing application. Second, inversion procedure implemented as statistically optimized fitting following Multi-Term Least Square minimization concept. It is realized for multi-pixel scenario when the retrieval is implemented simultaneously for a large group of coordinated observations, e.g. over several pixels of satellite image or by a network of ground-based instruments. This multi-pixel approach provides significant advantages in various applications, especially in satellite remote sensing. GRASP development is inspired by an idea of a standardized base-line reference algorithm for applications of various complexity. GRASP has been already used for interpreting ground-based and satellite data from both passive and active measurements. For example, GRASP has been used for retrieval of aerosol from ground-based sun-photometer and lidar observations, and from their combination as, for example, it is realized in frame of ACTRIS European network data processing. Also, GRASP has been used for developing retrieval from various passive satellite sensors including POLDER, 3MI/EPS-SG, Sentinel-3, -4, -5P, -7, HARP/Cubesat, MERIS, AATSR/Envisat, MISR, HIMAWARI, SGLI/GCOM, etc. and recently was used for evaluating potential of synergy of lidar and polarimeter observation in frame of  NASA/AOS initiative.

GRASP has been realized as open source software that can be used and modified by the community (http://www.grasp-open.com/). The, time performance and friendliness of open source software is constantly improved and supplementary tools for  results analysis and visualization are being created.



Dr Oleg DUBOVIK specializes in retrievals of aerosol properties from satellite, ground-based, and airborne remote sensing observations. Dr. Dubovik has received his PhD. from Institute of Physics, Minsk, Belarus in 1992. Then, he worked in Japan for two years, participating in ADEOS/ILAS algorithm developments, and nine years in USA at GSFC/NASA research center. Since 2006, Dr. Dubovik works in the Laboratoire d'Optique Atmosphérique, Université Lille, France as CNRS “Research Director”. Main scientific accomplishments of Dr. Dubovik include following developments: - aerosol retrieval algorithm for AERONET federated network of ground-based radiometers (https://aeronet.gsfc.nasa.gov)- one of pioneering climatologies of absorption and optical properties of ambient tropospheric aerosol; - popular efficient software for modeling scattering by non-spherical aerosol particles. Dr. Dubovik focuses on refinement of methodological aspects of numerical inversion for needs of remote sensing by applying elaborated statistical optimization approach. The developed principles were recently realized GRASP open source algorithm (https://www.grasp-open.com/) that can be applied to retrieval detailed aerosol properties fro diverse observations including both passive and active observations from satellite or ground. For example, GRASP is used in multiple algorithm development for deriving extended set of parameters from ground-based observations by lidar and radiometer (e.g., in operational processing frame of European ACTRIS infrastructure) satellite observations by POLDER-1,-2,-3, MERIS and AATSR/Envisat, Sentinel -3, -4, -5P, 3MI/EPS-SG, MAP/CO2M, etc.


Dr. Dubovik is (co-) author of 5 book chapters and more than 260 publications in peer-reviewed scientific journals . Dr. Dubovik has 4 first-authored papers have more than 1000 citations each. Dr. Dubovik is a recipient of NASA Medal for Public Service that recognizes exceptional contributions to NASA mission. In 2010 Dr. Dubovik was elected a fellow of American Geophysical Union.


Contact: Zhanqing Li

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