Abstract
Abstract. This article presents the coupling of the JULES surface model to the CCATT-BRAMS atmospheric chemistry model. This new numerical system is denominated JULES-CCATT-BRAMS. We demonstrate the performance of this new model system in relation to several meteorological variables and the CO2 mixing ratio over a large part of South America, focusing on the Amazon basin. The evaluation was conducted for two time periods, the wet (March) and dry (September) seasons of 2010. The model errors were calculated in relation to meteorological observations at conventional stations in airports and automatic stations. In addition, CO2 mixing ratios in the first model level were compared with meteorological tower measurements and vertical CO2 profiles were compared with observations obtained with airborne instruments. The results of this study show that the JULES-CCATT-BRAMS modeling system provided a significant gain in performance for the considered atmospheric fields relative to those simulated by the LEAF (version 3) surface model originally employed by CCATT-BRAMS. In addition, the new system significantly increases the ability to simulate processes involving air–surface interactions, due to the ability of JULES to simulate photosynthesis, respiration and dynamic vegetation, among other processes. We also discuss a wide range of numerical studies involving coupled atmospheric, land surface and chemistry processes that could be done with the system introduced here. Thus, this work presents to the scientific community a free modeling tool, with good performance in comparison with observational data and reanalysis model data, at least for the region and time period discussed here. Therefore, in principle, this model is able to produce atmospheric hindcast/forecast simulations at different spatial resolutions for any time period and any region of the globe.
Highlights
Before the beginning of the industrial era, around the year 1750, the atmospheric carbon dioxide (CO2) concentration was roughly 280 ppm, but has continually increased since (Keeling, 1997)
– METAR and PCDs: Observations from surface meteorological stations installed at airports (METAR) and automatic stations (PCDs) installed and maintained by the National Institute of Meteorology (INMET)
This study aimed to include in CCATT-BRAMS model the surface model Joint UK Land Environment Simulator (JULES) which is today considered state-of-theart
Summary
Before the beginning of the industrial era, around the year 1750, the atmospheric carbon dioxide (CO2) concentration was roughly 280 ppm, but has continually increased since (Keeling, 1997). The terrestrial biosphere continually sequesters 20 to 30 % of anthropogenic CO2 emissions, and studies suggest that Amazonia has been one of the largest contributors to atmospheric CO2 removal (Baker et al, 2004). In South America, during the biomass burning season, fires represent the largest source of atmospheric CO2; various other gases are emitted, which contribute to the greenhouse effect either directly or indirectly through the formation of secondary gases, such as ozone. It has been suggested that the interaction between biomass burning aerosols and solar radiation alters the photosynthesis process in the Amazon rainforest through the attenuation of the amount of solar radiation arriving at the surface and via the increase of the diffuse fraction (Yamasoe et al, 2006). The potential impact of all these processes can be considerable since, during the peak of the fire season, smoke plumes can cover areas of millions of km (Prins et al, 1998)
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