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We present a new version of the Brazilian developments on the Regional Atmospheric Modeling System where different previous versions for weather, chemistry and carbon cycle were unified in a single integrated software system. The new version also has a new set of state-of-the-art physical parameterizations and greater computational parallel and memory usage efficiency. Together with the description of the main features are examples of the quality of the transport scheme for scalars, radiative fluxes on surface and model simulation of rainfall systems over South America in different spatial resolutions using a scale-aware convective parameterization. Besides, the simulation of the diurnal cycle of the convection and carbon dioxide concentration over the Amazon Basin, as well as carbon dioxide fluxes from biogenic processes over a large portion of South America are shown. Atmospheric chemistry examples present model performance in simulating near-surface carbon monoxide and ozone in Amazon Basin and Rio de Janeiro megacity. For tracer transport and dispersion, it is demonstrated the model capabilities to simulate the volcanic ash 3-d redistribution associated with the eruption of a Chilean volcano. Then, the gain of computational efficiency is described with some details. BRAMS has been applied for research and operational forecasting mainly in South America. Model results from the operational weather forecast of BRAMS on 5 km grid spacing in the Center for Weather Forecasting and Climate Studies, INPE/Brazil, since 2013 are used to quantify the model skill of near surface variables and rainfall. The scores show the reliability of BRAMS for the tropical and subtropical areas of South America. Requirements for keeping this modeling system competitive regarding on its functionalities and skills are discussed. At last, we highlight the relevant contribution of this work on the building up of a South American community of model developers.

This paper reviews recent progress made in our understanding of the functioning and variability of the South American Monsoon System (SAMS) on time scales varying from synoptic to long-term variability and climate change. The SAMS contains one of the most prominent summertime climate patterns in South America, featuring a strong seasonal variability in a region lying between the Amazon and the La Plata Basin. Much of the recent progress is derived from complementary international programs, such as the Monsoon Experiment South America (MESA), as well as from ongoing international programs such as the Large Scale Biosphere Atmosphere Experiment in the Amazon Basin (LBA) and the La Plata Basin (LPB) Regional Hydroclimate Project, which includes the CLARIS LPB Europe-South America Network for Climate Change Assessment and Impact Studies in La Plata Basin Project. The latter assesses atmosphere-land surface interactions, the role of land use changes and aerosols from biomass burning considered as sources of variability and change in the SAMS functioning, characteristics and behaviour. The SAMS region is particularly susceptible to variations of climate due to the importance of hydroelectricity generation and the agricultural base of local economies. Also addressed in this report are projections of climate change and extremes, which are important for impact and vulnerability assessments. This discussion includes the need to identify and understand important processes that control the monsoonal climate, how these processes may vary and change, and how they may interact with key societal sectors, including water resource management, hydroelectric generation, agriculture, and agribusiness. This paper reports on the major contributions of MESA to the knowledge of characteristics, functioning and variability of the SAMS, and is based on recent studies and publications, and can be considered as an update of a previous review by C. S. Vera et al. (2006a). Copyright © 2010 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

This study is aimed to qualitatively analyze the impact of remote sources on air pollution in the Metropolitan Area of São Paulo (MASP). Air-mass back trajectories from June to August of 1999 were calculated using a three-dimensional kinematic trajectory model and grouped into trajectory clusters. Correlations of individual trajectory clusters with O3, CO and PM10 concentrations were determined. In this model, trajectories were obtained using the means of the three wind velocity components (U, V and W). The three-dimensional wind field was derived from the Regional Atmospheric Modeling System, and downscaling was employed. Coarse and fine nested grids (64-km and 16-km horizontal resolution, respectively) were used. Every 12 h (at 00 and 12 UTC), a back-trajectory ensemble, using the 64-km grid, was calculated for five defined endpoints at intervals of 0.5° N, S, E and W of the MASP (λ = 23° 33′S, ϕ = 46° 45′W), that last endpoint being centered in the MASP. To analyze cluster trajectories, the five trajectory ensembles from each day were allocated into one of four clusters (northeast, southeast, southwest or northwest quadrant) based on the origin of the trajectory over 4 days. Days on which all five trajectories originated from the same quadrant were classified as “core” days. Core day concentrations of CO, O3 and PM10 during the study period were evaluated. The results show that, during the study period, air-mass back trajectories in the MASP originated from all four quadrants: northeast (32%), southeast (12%), southwest (19%) and northwest (37%). Our analysis of back-trajectory clusters in the MASP suggests a transport to ambient air of O3 precursors and O3 from the northeast region, which is associated with agricultural activities involving biomass burning. [ABSTRACT FROM AUTHOR]