Vertical distribution of type-discriminated aerosol concentration from a three-wavelength backscatter spaceborne lidar

We present an innovative retrieval approach called AEROTYPro/GRASP (Aerosol Type Profiling/Generalized Retrieval of Aerosol and Surface Properties) to quantitatively discriminate the vertical profiles of five distinct aerosol types simultaneously present in the atmosphere, corresponding to smoke, continental, oceanic, dust, and urban polluted. Along with their abundances, it also derives bulk optical and microphysical properties for the total aerosol mixture (those of individual aerosol types are assumed). These are original capabilities compared to Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) spaceborne backscatter aerosol typing approaches, which offer a qualitative identification of the most probable aerosol type. AEROTYPro is here designed to use measurements of spaceborne multi-wavelength backscatter lidars, such as the one called LUCE, initially conceived to be part of the Atmosphere Observing System (AOS) mission formulation development program. This newly developed AEROTYPro retrieval approach is here implemented using simulations from the chemistry transport model (CTM) Modèle de Chimie Atmosphérique de Grande Echelle (MOCAGE) to derive a pseudo-reality. Simulated aerosol concentration profiles are used to calculate lidar signals of attenuated backscatter and depolarization vertical profiles at 355 nm, 532 nm, and 1064 nm. Then, these synthetic lidar signals are utilized as inputs of AEROTYPro to retrieve pseudo-observations of vertical profiles of aerosol types and their bulk optical and microphysical properties. Our findings show a satisfactory performance of AEROTYPro for retrieving aerosol mixing ratio vertical profiles for smoke, continental, oceanic, dust and urban polluted aerosol types, even when several aerosol types are present at the same locations and altitudes in the atmosphere. For this, we use the GRASP algorithm with distinct initial guesses of mixing ratio vertical profiles for each aerosol type, which are identical for all pixels. The other variables, such as aerosol optical depth (AOD) at 532 nm, single scattering albedo (SSA), lidar ratio (LR), absorbing aerosol optical depth (AAOD) and effective radius (R eff ), are also in good agreement with the pseudo-reality. These results are obtained for both a detailed single-transect analysis describing several aerosol outbreaks and 18 complete orbits covering the whole globe with a similar global coverage as daily CALIOP spaceborne lidar measurements. This shows that our retrieval approach can retrieve quantitatively aerosol vertical profiles for five distinct types, along with other aerosol properties across the globe based on multiwavelength backscatter lidar measurements. These AEROTYPro-derived aerosol properties present a significant opportunity for developing innovative applications in air quality assessment and direct and indirect aerosol radiative forcing analysis. • We developed an innovative retrieval approach called AEROTYPro. • It derives a global quantitative discrimination of vertical concentration profiles for five aerosol types, that may be simultaneously present in the atmospheric column. • Provides global bulk optical and microphysical properties. • Robust performance accounting variabilities in aerosol intensive properties.