The radiative impact of aerosols emanating from biomass burning, through the Minnaert constant

Abstract

Forest fires release gases, ashes and particulate matter into the atmosphere, affecting the atmospheric radiation budget. The increment of aerosols by particles emanating from biomass burning affects solar radiation, mainly in the troposphere, by multiple scattering and interactions between molecule and aerosol scattering for several days after the fire. Among the topographic normalization methods, the Minnaert method assumes the anisotropic reflectance of surfaces by introducing the Minnaert constant, the value of which is affected by the atmospheric diffusion of light. In this paper, a methodology is developed in order to study atmospheric effects on this value. This is based on the optimum value of the Minnaert constant, which is the value that leads to the higher classification accuracy. The methodology has been tested on four Landsat TM and three SPOT XS images respectively. The optimum Minnaert value presented a high decrement (0.1–0.2 instead of 0.8–0.9) for two images. Both of them had been captured shortly after fires, without being visibly affected by smoke and atmospheric perturbation effects. The proposed methodology has successfully revealed fires through the Minnaert constant. This methodology has also revealed the quality of the image. Sahara dust events are also to be investigated through the Minnaert constant.