Climate change and its effects on the Amazon environment
The planet Earth is undergoing a change in the composition of the atmosphere, where changes in concentrations of greenhouse gases and the amount of aerosols are altering the global atmospheric radiative balance significantly (IPCC 2007). The role of aerosol particles as the largest uncertainty in current global climate system is strongly recognized (Forster et al., 2007).
The Amazon region is undergoing significant changes in land use, being very important in terms of global climate change. Andreae et al. (2002) had suggested a strong link between biogenic emissions, especially primary biogenic emissions, and the hydrological cycle in Amazonia, similar to the work of Claes et al., 2004, where emissions of volatile organic compounds (VOCs) emitted by the primary forest were pointed as playing an important role on the production of cloud condensation nuclei (CCN). The LBA works have also shown that aerosol particles have a strong connection with the assimilation of Carbon in the vast area of the Amazon Basin. It is well established that aerosol particles play an important role in the biogeochemistry, climate and hydrological cycle in Amazonia. It is critically important to reduce the uncertainty of the impact of aerosols on climate, and Amazon is one of the critical regions to study these effects for a large number of reasons. In particular, it is important to identify and quantify the sources and processes regulating the regional concentrations of aerosols to better quantify their impacts. Feedbacks between climate and aerosol concentrations will only be fully understood when to disclose the factors that control the natural concentration of aerosols in regions like the Amazon.
Objectives of this subproject
- Study the climatic effects of aerosol particles and how changes in land use in Amazonia may influence the properties and composition of the atmosphere;
- Through the use of in situ measurements and remote sensing, to analyze the variability of the optical properties of aerosols in large scale in the Amazon. Perform physical characterization of natural biogenic aerosol particles;
- Determine the changes that the atmospheric radiation balance is suffering from the Amazon region and analyze its effects on the ecosystem. Calculate the radiative forcing of aerosols in the Amazon during the wet and dry season, with its uncertainty;
- Develop tools and analytical methods using remote sensing to study the spatial and temporal distribution of aerosol and microphysical properties of clouds in the Amazonian region;
- Quantify the processes that control the radiative forcing of aerosols in the Amazon region, as well as their uncertainties and perform a sensitivity analysis of key parameters such as scattering and absorption properties, effect of hygroscopicity and chemical composition of the particles, and nucleation capacity of clouds;
- Obtain the spatial distribution of cloud condensation nuclei (CCN), integrating the size distribution of particles and using the Köhler parameterization. Evaluating the effects of physical and chemical properties of aerosols in CCN distribution and the radiative properties of clouds;
- Modeling the large-scale transport of aerosol particles and gases in the atmosphere, especially emissions from forest fires. Develop parameterizations of processes to include them in the global climate model at INPE.
Methodology to be employed
The aerosol particles and clouds are basic components in the terrestrial energy balance, although its role is still far from being understood. The main sources of aerosol particles in the Amazon are primary biogenic emissions from forest, secondary aerosols from oxidation of VOCs, soil dust, sea salt emissions from forest fires, among others.
The organic particles formed from gaseous precursors are mostly trendy fine (Dp<2um) and can become cloud condensation nuclei through the clustering of water vapor. Therefore, the optical properties and microphysics of clouds in the Amazon region are strongly influenced by such particles.
Consequently, the hydrological cycle and the direct and indirect radiative balance can be affected by changes in the population of biogenic atmospheric aerosols. The aerosol particles directly interact with the incoming solar radiation through scattering and absorption, reducing the solar flux at the surface, decreasing the surface temperature. The scattering can be simple when the incident radiation is shifted from the original direction, or multiple, when radiation is scattered by other particles in the direction of interest. Therefore, scattering can increase or decrease the amount of radiation in a given direction. The elimination or attenuation of radiation is simply the sum of the scattering and absorption. The theory that deals with the interaction of radiation with particle diameter of the same order of magnitude or larger than the wavelength of incident radiation, as in the case of aerosols in relation to solar radiation, is the Mie theory. The physical characteristics of the aerosol that define how these particles interact with radiation are called optical properties, and, among them, the most important are the aerosol optical thickness, single scattering albedo and complex refractive index.
One of the weakest points of the models of aerosols is to determine the variability of its properties. In order to describe the direct radiative forcing, it is required a greater knowledge of the spatial distribution of mass concentration, chemical composition and size, the degree of mixing of various chemical species and the complex refractive index.
This proposal will also help the implementation of the ATTO project (Amazon Tall Tower Observatory), collaboration between the Brazilian and German governments. In ATTO, a 320 meters tower will be installed close to Balbina in Central Amazonia. The idea is to measure greenhouse gases, aerosols, turbulence properties in the central part of the basin and to estimate the carbon fluxes over a large area of the forest.
We intend to operate for five years an atmospheric monitoring station in Manaus and the other in Porto Velho, Rondonia. Also, the implementation of the ATTO tower by 2012 is part of the project goals.
We will carry out several experiments in international partnership with the University of Stockholm (Sweden), Max Planck Institute (Germany), NASA, and Harvard University (U.S.).
The main product of this subproject is to increase scientific knowledge about the basic functioning of the Amazon ecosystem and how this basic operation is being altered by changes in land use in the Amazon and climate change. This subproject will also add research groups in interdisciplinary works and insert the integration of work groups at USP in a whole new level of scientific collaboration.