One of our major goals at ATTO is understanding how the Amazon rainforest interacts with the atmosphere above. This includes studying how the characteristics of the air change within and above the tree canopy in terms of atmospheric turbulence. The strength of the wind and the thickness of the canopy determine, among other things, how well the air can mix and to what degree gases from the atmosphere may reach the forest floor and vice versa.
In a new study, the scientists were looking into these processes at two Amazon sites, including ATTO. They found that the lowermost air-layer from the forest floor to about half the tree height is largely decoupled from the air in the upper part of the canopy and above. That is an important finding, as this process may limit the extent to which plant-emitted gases are transported out of the forest canopy into the atmosphere above.
Raoni Aquino and co-authors now published their findings in a new study called “Air turbulence characteristics at multiple sites in and above the Amazon rainforest canopy” in the journal Agricultural and Forest Meteorology, Volume 260-261.
In a new study, Anne Mendonça, Cléo Quaresma, Daniel Marra and their co-authors analyzed different turbulence regimes at the ZF2 site as part of the ATTO-INVENTA project. They also investigated how turbulence is connected to the occurrence of downdrafts and extreme wind gusts, that might lead to tree mortality.
In a new study, Luca Mortarini and his colleagues introduce a novel approach to the study of the roughness sublayer, using a cospectral budget model. Its originality lies in not considering the mixing layer analogy to parameterize the turbulence statistics. In addition, it relates them to the different scales of the wind velocity spectrum without making any assumption on the property of the flow.
Eiky Moraes, Cléo Dias-Júnior and their colleagues wanted to find out if the local topography at the ATTO influenced the atmospheric movements. In particular, they were interested in the effect that topography has on the formation of gravity waves. Comparing two simulations, one with and one without topography, revealed some important differences in the dynamics and chemistry of the atmosphere.
Only when the air inside of the forest canopy mixes with the air above can there be exchange. The physical movement of the air, its turbulence, determine how well these two layers of air, the one inside the forest canopy and the one above, mix. Daniela Cava, Luca Mortarini, Cleo Quaresma and their colleagues set out to address some of these questions with two new studies that they conducted at ATTO. They wanted to define the different regimes of atmospheric turbulence or stability (Part 1) and describe the spatial and temporal scales of turbulent structures (Part 2).
Polari Corrêa and his co-authors analyzed the atmospheric dynamics in and above the forest canopy during one particular night at ATTO. Those conditions changed throughout the night. Turbulence was followed by the formation of a gravity wave and a low-level jet. It was likely formed due to the breeze from the Uatumã River and the hilly terrain. The study highlights the complex dynamics and mechanisms in the atmosphere above a dense forest.
Convective storms often occur in the tropics and have the potential to disturb the lower part of the atmosphere. They might even improve the venting of trace gases out of the forest canopy into the atmosphere above. To better understand these processes, Maurício Oliveira and co-authors used the infrastructure at ATTO to study storm outflows during nighttime. They published the results in a new paper in the Open Access Journal Atmospheric Chemistry and Physics.
The Amazon rainforest interacts with the atmosphere by exchanging many substances. Many of these, such as carbon dioxide, methane, ozone, and organic compounds, are produced by the vegetation. They are very influential in both the regional and global climates. Until now, the estimates of their emission and absorption rates are based on classical theories. But those were developed over relatively short vegetation and are valid for the so-called “inertial sublayer.”