DARTs of light in the Amazon

Hello everyone, my name is Jeová Ramos da Silva Junior. I am a meteorologist and had my first contact with ATTO at the beginning of my master’s degree in 2017. During this period, I investigated how biomass burning might affect photosynthesis inside the canopy of the Amazon Rainforest.

This might seem far-fetched at first, but one of the main drivers of photosynthesis is radiation, meaning simply sunlight. When there are plumes of biomass burning in the atmosphere, the amount of aerosols in the atmosphere increases. And those particles reflect and diffuse the radiation in the canopy. Consequently, the radiation can reach a larger number of leaves in the canopy. This leads to an increase in the rates of photosynthesis, which we can observe through the removal of atmospheric CO2.

Then I used data from 9 sensors distributed along the whole height of the ATTO tall tower to analyze the radiation propagation, and a special sensor to measure the number of aerosols above the forest. I fed these data into a computer simulation, a 3D radiative transfer model called DART (Discrete Anisotropic Radiative Transfer) developed by CESBIO (Center for the Study of the Biosphere from Space) in France. This model is very robust and has many specific features. One of the coolest is that you can recreate a very detailed, realistic scenario. Other models can often be quite abstract and generic. The DART model allows me to insert, for example, a car, a lake, ultra-realistic buildings, or even a giant tower surrounded by forest. The result is something much richer and more detailed in both the atmospheric and soil parts.

With this model, it was possible to identify and describe the dynamics of the region and how it benefited from the spreading of the radiation. We could take into account the position of the sun and the number of aerosols. And we could do this specifically for the local landscape, such as trunks, branches and even the ATTO tower itself.

Jeová can create an ultra-realistic simulation of the Amazon rainforest and the ATTO tower with the model DART.
Jeová can create an ultra-realistic simulation of the Amazon rainforest and the ATTO tower with the model DART.

I remember that one clear night at the institute I was waiting for the model to finish running. I used the time to make the first graphics and could observe the movement of the shadows of the trees throughout the day. In these shadows, there were small details, such as gaps where the direct sunlight passed freely until it reached the ground. It was a very remarkable moment for me because besides checking the realism of the model it was all very beautiful.