GoAmazon

The GoAmazon experiment seeks to understand how aerosol and cloud life cycles are influenced by pollutant outflow from Manaus in the tropical rain forest. Particularly, the susceptibility to cloud-aerosol-precipitation interactions and the feedbacks among biosphere and atmosphere functioning and human activities. The scientific objectives are organized as Aerosol Life Cycle (ALC), Cloud Life Cycle (CLC), and Cloud-Aerosol-Radiation-Precipitation Interactions (CAPI). One of the focus is to understand the production of secondary organic aerosol (SOA) from the interaction of urban pollution emissions with VOCs emitted from the forest. Manaus is a 2 million people urban area surrounded by hundreds of kilometers of forest, and the study of atmospheric processes in this interaction is important to regional and global climate change assessments. A set of detailed aerosol, trace gases and cloud measurements will be performed over 6 different sites, followed by detailed meteorological transport studies. Atmospheric properties measurements will take place before the Manaus plume on three sites (ATTO (site T0), ZF2 (site T01) and EMBRAPA (site T02)), 2 sites will be located downwind of the Manaus plume (Iranduba (site T2), close to the Negro River and Manacapuru (site T3)) and one site will be operated downtown Manaus. This FAPESP proposal involves the installation and operation of all 3 upwind sites (ATTO, ZF2 and EMBRAPA) and Iranduba. The data analysis and modeling, nevertheless will make use of all GoAmazon sites and data. In Manacapuru, US DoE will operate the ARM Mobile Aerosol Observing System (MAOS-A and C) and the ARM Mobile Facility #1 (AMF1). In the sites operated by this proposal, a large set of measurements will be performed: aerosol optical measurements with spectral light scattering and absorption, aerosol size distribution, aerosol composition for organic and inorganic components, CCN (Cloud Condensation Nuclei), aerosol optical depth, radiation balance, atmospheric vertical thermodynamic structure among other measurements. Four aerosol mass spectrometers will be deployed to measure organic and inorganic aerosol composition with 30 minutes time resolution in several locations. Raman Lidar will measure the vertical distribution of aerosols and water vapor up to 12 Km. Trace gases such as O3, CO, CO2, CH4, SO2 and detailed VOCs characterization will also be determined. Measurements of cloud properties including cloud cover fraction, droplet size distribution, precipitation, water vapor and others will be combined with cloud and precipitation radars for a regional assessment of cloud-aerosol- precipitation relationship. Boundary layer thermodynamic properties will be measured with radiosondes in several sites. High resolution BRAMS regional modeling will be performed daily with 2 km resolution and full aerosol and trace gas chemistry. High resolution cloud modeling will integrate aerosol, CCN, water vapor and thermodynamic conditions for a variety of conditions. The GoAmazon measurements and modeling framework will provide a dataset vital to constrain tropical forest model parameterizations for organic aerosols, cloud and convection schemes, and radiation balance. The dataset also will provide insights into how these are perturbed by pollution and how they influence climate regionally and globally.

Objectives of the proposed work This work is the Brazilian component of the GoAmazon experiment, and as such, responds to the white paper: GoAmazon 2014 Workshop Report (DoE SC-0141 Report, 2012), and the document on the Intensive Operating Periods. A large set of key scientific questions were formulated at the GoAmazon workshops. The key questions and objectives for this proposal are in 4 main topic areas:

• Secondary Organic Aerosol (SOA) formation: Interactions of biogenic and anthropogenic emissions

• Influence of the Manaus Pollution Plume on Aerosol Microphysics: Particle Size Distributions, Optical Properties, and Cloud Condensation Nuclei (CCN) Activity

• Biogenic Volatile Organic Compound (BVOC) Emissions and impact on atmospheric chemistry and aerosol production

• Impact of aerosol particles on cloud processes and precipitation in Amazonia.

We propose to use observations from a large range of instruments, remote sensing from surface and satellite based sensors, and numerical modeling of physical processes acting in several spatial and temporal scales as tools to advance the understanding of the underlying processes expressed in the above questions. Detailed objectives based on these critical questions and issues are as follows:

Aerosol Life Cycle

1. Study process and interactions of the Manaus pollution plume with biogenic emissions of VOCs, especially the impact on the production of secondary organic aerosol (SOA) and the formation of new particles;

2. To measure the aging of biomass burning plumes and the subsequent formation of additional SOA;

3. The influence of anthropogenic emissions i.e., (a) the Manaus pollution plume and (b) biomass burning aerosols on aerosol microphysical, optical, CCN, as obtained by comparing the aerosol properties between pristine and anthropogenically influenced air masses; and

4. Determine the optical properties of aerosols from the interaction of the Manaus plume and the natural vegetation atmosphere and obtain the aerosol radiative forcing.

Cloud Life Cycle

1. Study the role of landscape heterogeneity (e. g., the urban area of Manaus or km-long scale of rivers) on the dynamics of convection and clouds;

2. The evolution of convective intensity from severe storms in the dry season to moderate storms in the wet season, and to consider how changes caused by local deforestation lead to similar transitions;

3. The transition from shallow to deep cumulus convection during the daily cycle of the Amazon Basin, with comparison and understanding to other ARM sites; and

4. Development of a knowledge base and test cases that will improve tropical cloud parameterizations in regional and global climate models (GCMs). Cloud-Aerosol-Precipitation Interactions

5. Aerosol effects on scattered cumulus clouds, especially the aerosol radiative effect, with a special focus on the impact of biomass burning aerosols;

6. Aerosol effects on deep convective clouds, precipitation, and lightning under different aerosol and synoptic regimes, including the roles of aerosols in changing regional climate and atmospheric circulation; and

7. Improvement of parameterizations of aerosol- cloud interactions in the regional and global climate models The ultimate goal is to estimate future changes in direct and indirect aerosol radiative forcing, energy distributions, regional climate, precipitation patterns, and feedbacks to global climate. A challenge of GoAmazon experiment will be to attribute cloud life-cycle characteristics to large-scale dynamic forcing, local thermodynamics including the influence of the Manaus heat island, and aerosols. To appropriately identify the relative impacts of these different forcing elements, characterizing the large-scale meteorology with high-resolution modeling will be important.