Overview of Operational Forecasts of the South American Regional Smoke Plume During the South American Biomass Burning Analysis (SAMBBA) Experiment
Friday, 19 December 2014
One of the major goals of the South American Biomass Burning Analysis (SAMBBA) campaign, which took place during the 2012 Amazonian dry season, was to enhance current knowledge on the South America regional smoke plume and its climate impacts in order to improve its representation in atmospheric and chemistry transport models. During the experiment, three atmosphere chemistry transport models - CCATT-BRAMS (Chemistry Coupled Aerosol-Tracer Transport model to the Brazilian developments on Regional Atmospheric Modeling System), a limited area model configuration of the Met Office Unified Model (MetUM) and MACC (Monitoring Atmospheric Composition and Climate modeling system) - were used to support and guide the experimental design by providing operational meteorology and chemistry forecasts. A comprehensive overview of these forecasts has been carried out aiming to characterize the operational performance of the models at the time of the campaign. The present analysis focuses on the evaluation of the ability of the models to simulate the spatial, daily and intra-seasonal variability of the regional smoke plume. In order to do so, the Aerosol Optical Depth (AOD) forecasts are used as a reference. Unlike CCATT-BRAMS and MetUM, MACC was running in AOD assimilation mode. In general all three models were able to capture the major features of the regional plume intra-seasonal variability, i.e., the beginning, peak and end of the biomass burning season, shown by AOD time series from AERONET sites located inside tropical forest and cerrado ecosystem regions. However, in terms of the spatial variability of the AOD magnitude, there is considerable divergence among the models. As expected, MACC (that included data assimilation of AOD) presented better performance when compared with observations. CCATT-BRAMS tended to overestimate AOD mainly over tropical forest regions in the southwestern portion of the Amazon basin and MetUM overestimated AOD across the cerrado area and over the southern portion of the Amazon basin. Likely factors related to these observed biases will be discussed.