The Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS) Part 1: Model description and evaluation

Abstract

We introduce the Coupled Aerosol and Tracer Transport model to theBrazilian developments on the Regional Atmospheric Modeling System(CATT-BRAMS). CATT-BRAMS is an on-line transport model fully consistentwith the simulated atmospheric dynamics. Emission sources from biomassburning and urban-industrial-vehicular activities for trace gases andfrom biomass burning aerosol particles are obtained from severalpublished datasets and remote sensing information. The tracer andaerosol mass concentration prognostics include the effects of sub-gridscale turbulence in the planetary boundary layer, convective transportby shallow and deep moist convection, wet and dry deposition, and plumerise associated with vegetation fires in addition to the grid scaletransport. The radiation parameterization takes into account theinteraction between the simulated biomass burning aerosol particles andshort and long wave radiation. The atmospheric model BRAMS is based onthe Regional Atmospheric Modeling System (RAMS), with severalimprovements associated with cumulus convection representation, soilmoisture initialization and surface scheme tuned for the tropics, amongothers. In this paper the CATT-BRAMS model is used to simulate carbonmonoxide and particulate material (PM2.5) surface fluxes and atmospherictransport during the 2002 LBA field campaigns, conducted during thetransition from the dry to wet season in the southwest Amazon Basin.Model evaluation is addressed with comparisons between model results andnear surface, radiosondes and airborne measurements performed during thefield campaign, as well as remote sensing derived products. We show thematching of emissions strengths to observed carbon monoxide in the LBAcampaign. A relatively good comparison to the MOPITT data, in spite ofthe fact that MOPITT a priori assumptions imply several difficulties, isalso obtained.