Brazilian Air Quality Forecast

Model setup
General
LOTOS-EUROS (Schaap et al., 2008) is a 3D chemistry transport model which simulates the air pollution in the lower troposphere over Europe. Currently, the model is used for operational air quality forecasts over Europe, as contribution to the Monitoring Atmospheric Composition and Climate (MACC) project, and over the Netherlands, published on the website of the National Institute for public health and environment (RIVM). In this study, we used the LOTOS-EUROS model (version 1.10) in the following configuration.

Domain and resolution
The domain spans from 6o to 33o South and 56o to 32o West with a grid resolution of 0.25o longitude by 0.125o latitude.
Vertical structure
The model extends in the vertical direction 3.5 km above sea level and consists of three dynamical layers, i.e., the mixing layer and two reservoir layers on top. The height of the mixing layer varies over time and space, and is extracted from the ECMWF (European Centre for Medium-range Weather Forecasts) meteorological input data that are used to drive the model. The height of the reservoir layers is set to the difference between the ceiling height (3.5 km) and mixing layer height. Both layers are equally thick, with a minimum of 50 m. Occasionally, the mixing layer extends near or above 3500 m, in which case, the top of the model exceeds 3500 m. A surface layer with a fixed depth of 25 m is included in the model to monitor ground-level concentrations.
Chemistry and physics
The chemistry is parameterised following a CBM-IV scheme (Schaap et al., 2008) and the aerosol chemistry is accounted for using the ISORROPIA parameterisation (Fountoukis & Nenes, 2007). N2O5 hydrolysis on secondary inorganic aerosol and sea salt is explicitly accounted for. The transport is represented by advection in three dimensions, vertical diffusion and entrainment. The dry deposition is parameterised following the resistance approach ( Wichink Kruit et al., 2012). The wet deposition process is represented by below cloud scavenging for gases (Schaap et al. 2004) and particles (Simpson et al., 2003).
Meteorology and boundary conditions
The model is driven using ECMWF meteorology and constrained by boundary conditions from the global MACC IFS/MOZART forecasts (Flemming et al., 2009).
Emissions
The anthropogenic emissions are prescribed following the EDGAR emission database for the year 2008. The biogenic emissions are calculated by means of the MEGAN model. To account for the occasional fire events, the MACC global fire assimilation system (Kaiser et al., 2012) is used on an hourly basis. The sea salt emissions are parameterized following source formulations for coarse (Monahan, Spiel, & Davidson, 1986) and fine (Mårtensson et al., 2003) aerosol modes.
Caveats
The following features are not included yet:
  • Lightning produced NOx;
  • soil NOx fluxes;
  • convective transport above the boundary layer.