Aerosol Modelling & Lessons Learned from GRASP Aerosol Remote Sensing

The presentation discusses the approaches to model aerosol properties realized in  GRASP (Generalized Retrieval of Aerosol and Surface Properties)  algorithm (Dubovik et al., 2021). GRASP algorithm  is developed based heritage of earlier efforts on the AERONET retrieval development (Dubovik and King, 2000, Dubovik et al., 2000)  with idea to use the same algorithm for different applications. Thus, at present, GRASP is a versatile algorithm that could be applied diverse observations including laboratory, passive and active remote sensing measurements from ground and space. All those observations have different sensitivities to details of aerosol properties and, therefore, analysis of each type of observations requires adequate approach to model aerosol properties. For example, aerosol model used for interpretation of  AERONET observations includes many more paraments than aerosol model used for interpretation of satellite observations from single view satellite imager such a MODIS or OLCI. At the same time, the aerosol models used for different observations should be consistent and compatible. Following this concept,  GRASP aerosol forward model can be adequately adjusted for applications to very different observations ranging from in situ nephelometers, ground-based AERONET radiometers to satellite polarimetric and radiometric imagers, as well as, to ground-based and satellite lidar observations. The  aerosol model   describes all aerosol properties: size distribution, complex index of refraction, or composition,  particle shape, rules of for several component mixing, vertical profile description, etc.  The presentation overviews historical evolution of all details of aerosol model, the assumptions made for adaptation to different observations of different types of and  the rational used for the current  specific design od aerosol model. Finaly, the comparative analysis will be done to outline the differences and agreements with other  common approaches used in aerosol remote sensing.  

Dubovik, O., A. Smirnov, B. N. Holben, etc., “Accuracy assessments of aerosol optical properties retrieved from AERONET Sun and sky-radiance measurements”, J. Geophys. Res.,105, 9791-9806, https://doi.org/10.1029/2000JD900040, 2000.

Dubovik, O. and M. D. King, “A flexible inversion algorithm for retrieval of aerosol optical properties from Sun and sky radiance measurements”, J. Geophys. Res., 105, 20,673-20,696, https://doi.org/10.1029/2000JD900282, 2000.

Dubovik, O., D. Fuertes, P. Litvinov, et al. , “A Comprehensive Description of Multi-Term LSM for Applying Multiple a Priori Constraints in Problems of Atmospheric Remote Sensing: GRASP Algorithm, Concept, and Applications”, Front. Remote Sens. 2:706851. doi: 10.3389/frsen.2021.706851, 2021.