Atmospheric CO2 budget over the Amazon basin: the role of convective systems

Valdir Herrmann,Saulo R Freitas

doi:10.1590/s0102-77862011000400003

Valdir Herrmann, Saulo R Freitas

Open Access

https://doi.org/10.1590/s0102-77862011000400003

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Abstract

This work studies the atmospheric CO2 budget in the Amazon basin, focusing on the role of shallow and deep convective systems. The vertical redistribution of CO2 is numerically simulated using an Eulerian transport model coupled to the Brazilian developments on the Regional Atmospheric Modeling System (BRAMS). The transport model includes grid-scale advection, diffusion in the PBL (Planetary Boundary Layer) and convective transport by sub-grid shallow and deep moist convection. In the simulation, the mass conservation equation is solved for six tracers, including or not the shallow and deep moist convection terms. The rectifier effect is also showed through simulation of the transport to the free troposphere of PBL air masses with low CO2 concentrations due to assimilation by vegetation during the afternoon, when both CO2 fixation and convection are at their peak. The model is applied to simulate July 2001 with a 30 km grid resolution covering the northwest part of South America. We compare the model results with airborne CO2 observations collected in the Amazon basin during the 2001 CLAIRE field campaign.

Highlights

The atmosphere is composed of a mixture of gases and aerosols, which interact with solar and terrestrial radiation
The CO2 budget is studied through numerical atmospheric modeling using the Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS, Freitas et al, 2005, 2009)
The transport model satisfactorily reproduced the general characteristics of the diurnal cycle of CO2 in the PBL, and its transport to the free troposphere by moist convective systems

Summary

Introduction

The atmosphere is composed of a mixture of gases and aerosols, which interact with solar and terrestrial radiation. Solar radiation is absorbed, reflected, and scattered in a complex combination of interactions with the atmosphere and ground surface. Part of the incident shortwave radiation is absorbed by the Earth’s surface and reemitted in the infrared (longwave) range. Chemical species such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), water vapor (H2O), and chlorofluorocarbons (CFCs), among others, absorb long wave radiation emitted by the Earth’s surface and atmosphere, producing the so-called “greenhouse effect,” responsible for life on Earth.

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