Jordi Vila-Guerau – Investigations on the relations between photosynthesis and clouds at the Amazon basin

CESOC kindly invites you to a Colloquium given by Prof. Dr. Jordi Vila-Guerau de Arellano, a Professor and Chairholder at Meteorology and Air Quality Group, Wageningen University & Research with the title:

Investigations on the relations between photosynthesis and clouds at the Amazon basin

Date: 23 May 2025,
Time: 10:00 CEST
Location: Lecture Hall 4.001 (4th floor), Höninger Weg 100, 50969 Cologne

For online participation, please contact: info[@]cesoc.net

Abstract:
How are rainforest photosynthesis and turbulent fluxes influenced by clouds? To what extent are clouds affected by local processes driven by rainforest energy, water and carbon fluxes? These interrelated questions were the main drivers of the intensive field experiment CloudRoots-Amazon22 which took place at the ATTO/Campina supersites in the Amazon rainforest during the dry season, in August 2022. CloudRoots-Amazon22 collected observational data to derive causal-effect relationships between processes occurring at the leaf-level up to canopy scales in relation to the diurnal evolution of the clear-to-cloudy transition. First, we studied the impact of cloud and canopy radiation perturbations on the sub-diurnal variability of stomatal aperture. We found an asymmetry modulated by clouds that favors photosynthesis in the morning. Second, we combined 1 Hz-frequency measurements of the stable isotopologues of carbon dioxide and water vapor with measurements of turbulence to determine carbon dioxide and water vapor sources and sinks within the canopy. Using scintillometer observations, we inferred 1-minute sensible heat flux that responded within minutes to the cloud passages. Third, collocated profiles of state variables and greenhouse gases enabled us to determine the role of clouds in vertical transport. We then inferred the area fraction of cloud cover and cloud mass flux to probe the need of collecting a comprehensive data set to establish causality between canopy and cloud processes and improve the representations in weather and climate models. These studies will be used to constrain numerical experiments carried out with large-eddy simulations to compare present and future scenarios influenced by warming and enhance carbon dioxide concentrations. Our findings contribute to advance our process knowledge of the coupling between cloudy boundary layers and primary carbon productivity of the Amazon rainfores