Aerosol distribution over Brazil with ECHAM-HAM and CAM5-MAM3 simulations and its comparison with ground-based and satellite data

The accurate representation of the impacts of natural and anthropogenic aerosols in the climate system presents a challenge in General Circulation Models. This paper analyzes the performance of the aerosol component of two Atmospheric General Circulation Models (AGCM): the Europe Centre Hamburg Model - Hamburg Aerosol Model (ECHAM-HAM), and the Community Atmosphere Model - Modal Aerosol Model (CAM5-MAM3) and their comparison with aerosol observations. We analyzed the spatial distribution of aerosols over Brazil represented in terms of the aerosol optical depth (AOD) simulated by these models. The model results are compared to measurements from Aerosol Robotic Network (AERONET) ground station, and satellite observations provided by the Moderate Resolution Imaging Spectroradiometer (MODIS). While both the models provide AODs at 550 nm, only HAM provides the Angstrom exponent that is compared with AERONET measurements. The comparison between the model simulations and the satellite observations of AOD show that the models can reproduce the spatial and temporal distributions, however models underestimate AOD for the four cities and for almost every South American continent during all seasons. During the dry season, characterized by intense biomass burning, CAM5-MAM3 shows inconsistent, but comparatively better results that ECHAM-HAM, with negative biases over Northern and Northeastern regions of Brazil. The Angstrom parameter is reasonably reproduced by ECHAM-HAM, except for Cuiaba, indicating that the particle size distribution is correctly represented in most cities. (c) 2017 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved. (AU)