Hyperspectral Remote Sensing of Biomass Burning Aerosol Plumes : Sensitivity to Optical Properties Modeling

摘要

In this paper, variations with wavelength of aerosol optical properties which are optical thickness τ, single-scattering albedo ω_0 and asymmetry parameter g are modeled using polynomial functions in the case of dense biomass burning plumes in the spectral range [ 0.4 - 1.1 μm ]. Optical properties are computed from Mie theory for various types of particles, size distributions and concentrations. In a first step, each optical property is fitted by polynomials with one, two and three parameters over the whole set of optical properties and then an error analysis is performed in order to choose the optimal number of parameters depending on wished accuracy. In a second step, the impact of modeling errors on top of atmosphere reflectance ρ~(TOA) is investigated depending on ground reflectance. The impact on ρ~(TOA) of ground reflectance variability under the smoke plume is also assessed. Calculations show that accurate modeling of spectral behaviour requires three parameters for τ and ω_0 and two parameters for g. It leads to simulations of ρ~(TOA) with an accuracy of about 0.001 which is compatible with the level of noise of current sensors. Using one less parameter for each optical property yields errors on ρ~(TOA) within 0.02.