Levy, R. C., L. A. Remer, and O. Dubovik, 2007: Global aerosol optical properties and application to MODIS aerosol retrieval over land . J. Geophys. Res., 112, D13210, doi:10.1029/2006JD007815..
As more information about global aerosol properties has become available from remotely sensed retrievals and in-situ measurements, it is prudent to evaluate this new information, 5
both on its own and in the context of satellite retrieval algorithms. Using the climatology 6
of almucantur retrievals from global AERONET sunphotometer sites, we perform cluster 7
analysis to determine aerosol type as a function of location and season. We find that three 8
spherical-derived types (describing fine-sized dominated aerosol), and one spheroid-9
derived types (describing coarse-sized dominated aerosol, presumably dust) generally 10
describe the range of AERONET observed global aerosol properties. The fine-dominated 11
types are separated mainly by their single scattering albedo (ω0), ranging from non-12
absorbing aerosol (ω0~0.95) in developed urban/industrial regions, to moderately 13
absorbing aerosol (ω0~0.90) in forest fire burning and developing industrial regions, to 14
absorbing aerosol (ω0~0.85) in regions of savanna/grassland burning. We identify the 15
dominant aerosol type at each site, and extrapolate to create seasonal 1° x 1° maps of 16
expected aerosol types. Each aerosol type is bi-lognormal, with dynamic (function of 17
optical depth) size parameters (radius, standard deviation, volume distribution) and 18
complex refractive index. Not only are these parameters interesting in their own right, 19
they can be applied to aerosol retrieval algorithms, such as to aerosol retrieval over land 20
from MODIS. Independent direct-sun AERONET observations of spectral aerosol optical 21
depth (τ) are consistent the spectral dependence of the models, indicating that our derived 22
aerosol models are relevant. 23
