ATTO- Amazon Tall Tower Observatory

Amazonia is a living laboratory to study critical processes that regulate tropical atmospheric chemistry and physics. The forest is an important global source of aerosols, trace gases and water vapor, and the complex nonlinear processes that regulate these different components are still not fully understood. In this project, we will study Aerosol Life Cycle (ALC), Cloud Life Cycle (CLC), and Cloud-Aerosol-Radiation-Precipitation Interactions (CAPI) in Amazonia, using a combination of approaches that allows innovative research in the tropics. The project comprises 4 measurement efforts: 1) New long term observations at the Amazon Tall Tower Observatory (ATTO); 2) Several fluvial expeditions in the untouched areas of Western Amazonia; 3) A large scale aircraft experiment with the HALO G5 high altitude plane (14 km); and 4) Aerosol and trace gas measurement campaigns at Chacaltaya, Bolivia, 5,240 altitude in the Andes, to study the transport and impact of Amazonian aerosols.

These measurement efforts, going from the ATTO 325 meters tall tower, through fluvial ship and aircraft up into the Andes at the GAW-WMO Chacaltaya station, will allow a large spectrum of critical processes that regulates the links between forest-atmosphere- climate in tropical regions. In these sites and platforms, we will measure, among other things, aerosol optical properties with spectral light scattering and absorption, aerosol size distribution, aerosol composition for organic and inorganic components, aerosol optical depth, radiation balance, cloud condensation nuclei, cloud droplet size, cloud optical depth, and vertical profiles of aerosols, clouds, precipitation and thermodynamic variables. A large set of advanced instrumentation will make these measurements in difficult logistical conditions. High resolution cloud modeling will integrate aerosol, CCN and water vapor for a variety of thermodynamic conditions and will allow integration of organic aerosol analysis with cloud processes. High-resolution BRAMS and WRF-Chem regional modeling will be performed to help understanding regional processes and transport.

With these new datasets and associated modeling efforts, we plan to study cloud- aerosol-precipitation interactions and the feedbacks between biosphere and atmosphere and human activities through deforestation and biomass burning emissions. We expect that these measurements and modeling framework will provide new insights in critical and important processes that regulate tropical atmospheric chemistry and cloud physics. The analysis will also provide insights into how Amazonia is being perturbed by biomass burning emissions and how it influences climate regionally and globally.

This project aims to study aerosols and clouds lifecycles, and their impact in the Amazonian ecosystem using long-term measurements at ATTO, river ships, the high altitude HALO airplane and measurements in the Andes (Chacaltaya). The key scientific questions to be answered by this project are composed by four main topics:

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

   • What are the chemical and physical processes that controls and affect the production of SOA in Amazonia?

   • How are (organic) particles produced (e.g., nucleation and SOA formation)?

   • What are the potential roles of primary particles (fungal spores, bacteria, and leaf cuticle) as cloud condensation nuclei (CCN)?

   • In the pristine Western Amazon, what is the contribution of the IEPOX-SOA component? What is the role of ELVOCs?

   • How SOA is formed and oxidized at high altitude (>12 Km)?

2. Links between particle size distributions, optical properties, and cloud condensation nuclei (CCN) activity

   • What are the main characteristics of the life cycle of aerosols in the Amazon, and what are the impacts of the biogenic, soil dust and long range transported biomass-burning emissions on the atmospheric chemistry in Central Amazonia?

   • What Is the impact of “Brown Carbon” (BrC) in aerosol absorption in pristine conditions? How is the partition between BrC versus BC absorption as function of biomass burning aging in Central and Western Amazonia?

   • How is the aerosol absorption in Central Amazonia linked with the atmospheric conditions leading to cloud formation, evolution and lifetime?

   • What is the influence of primary and secondary organic aerosols on the cloud condensation nuclei (CCN) activity and in the hygroscopicity parameter Kappa?

3. Biogenic Volatile Organic Compound (BVOC) emissions and impact on atmospheric chemistry and aerosol production

   • What are the characteristics of BVOCs emission from vegetation, and how do they vary with season and climate conditions?

   • In BVOC emission, what are the roles of the physical environment (e.g., temperature, rainfall, radiation, and nutrients), environmental perturbations (e.g., drought, nutrient deposition, and temperature extremes)?

   • What is the relative contribution of isoprene oxidation products ISOPOOH (low NOx conditions) and MVK+MACR in Western Amazonia?

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

   • What is the more appreciated microphysical parameterization for shallow and deep convective clouds in the Amazonas region?

   • What are the physical parameters that improve model rainfall field descriptions in the Amazonas region.

   • What are the physical parameters controlling the Amazonas cloud organization and life cycle in convective parameterization models?

   • What are the controls of cloud microphysics, aerosols and cloud dynamics upon cloud life cycle and rainfall in the Amazon region?

   • What are the controls of clouds mixed phase in the Amazonas region?

   • What are the relative roles into convective cloud intensity and severity in the Amazon of large scale dynamics, local thermodynamics and aerosol concentration?

   • What controls the transition between shallow and deep convection in the Amazon region and why models do not simulate this transition properly?

   • How is the diurnal cycle of convective activity linked to aerosol variability?

   • What is the relative impact of surface features, such as large rivers and land use features and patterns of deforestation, and aerosols upon convective cloud life-cycle?

We propose to use long-term observations from the ATTO tower, boat measurements in Western Amazonia, observations over the Andes, high altitude aerosol and trace gas measurements using the HALO plane to answer these questions. We will use a 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.

The main theme uniting these objectives is the development of a data-driven knowledge base for predicting how the present-day energy and mass flows in the Basin might change by internal forcing prevenient from projected changes in the Basin. Our ultimate goal is to estimate future changes in direct and indirect radiative forcing, energy distributions, regional climate, and feedbacks to global climate by improving our understanding of the basic processes controlling the atmospheric chemistry, clouds, precipitation, mass and energy fluxes in Amazonia.