International Actris 2024 Science Conference

INSA was well represented at the recent International Actris Science conference which took place from May 13 – 16 in Rennes, France. ACTRIS is a pan-European research infrastructure producing high-quality data and information on short-lived atmospheric constituents, as well as on the processes that lead to variability of these constituents in both natural and controlled atmospheres (

From left: Corinne galy-Lacaux, Venance Donnou, Marcellin Adon, Adama Bakayoko, Mohamed Diaby, Claire Delon.

The four-day science conference brought together members of different atmospheric science communities, such as air quality and climate research. Four INSA project participants presented recent research that has been partially completed in the framework of the INSA project.

Mohamed Diaby (Félix Houphouët-Boigny University, Côte d’Ivoire) gave a presentation on the chemical characteristics of rainwater and wet atmospheric deposition fluxes at two urban sites and one rural site in Côte d’Ivoire (Diaby et al. 2023).  The study highlights that urban rainfall is much more chemically loaded compared to the rural area of Lamto, with a mean annual ionic load estimated to be twice as high in Abidjan than in Lamto. Results also suggest that rain content at urban sites is more likely to be determined by local emissions than large-scale and climatic influences.This unique study on rainfall composition represents a first step toward understanding the composition of the atmosphere in African cities. Quantifying key deposition elements, such as nitrogen, for urban areas is important for closing the gap in regional budgets of ionic species, which is necessary for policymakers to manage atmospheric inputs and outputs at the local scale.

Venance Donnou (Abomey Calavi University, Benin) gave a presentation on long-term measurements of ozone concentrations in semi-natural African ecosystems (Donnou et al. under review). Donnou and coauthors are investigating the contribution of local atmospheric chemistry and meteorological parameters to ozone photochemistry, as well as studying long-term trends in ozone concentrations. Very few surface ozone measurements exist in Africa, and the long-term results presented in this study are the most extensive for the studied ecosystems.

Marcellin Adon (Université Jean Lorougnon Guédé (UJLoG), Côte d’Ivoire) presented a poster on modelling the effect of biogenic NO emissions from soils on atmospheric chemistry simulations over Africa. Adon and his colleagues Fabien Solmon (Laero, CNRS/UT3-UPS) and Eric Yao (PhD student, UJLoG), are developing an integrated modeling tool based on a regional climate model (ICTP/RegCM5) coupled to the Community Land Model (CLM5.0).  A key step in validating the model has been comparing simulated outputs to measurements made by the International Network to study Deposition and Atmospheric composition in Africa (INDAAF), coordinated by Corinne Galy-Lacaux (Laero, CNRS/UT3-UPS).  The tool will be used to perform long-term simulations to analyse the impact of climate variability and changing anthropogenic emissions on the regional atmospheric nitrogen budget.

Adama Bakayoko (Félix Houphouët-Boigny University, Côte d’Ivoire) presented a poster on the calculation of a regional nitrogen budget in the Lake Victoria catchment (Bakayoko et al. 2021). Bakayoko and colleagues use rare and original in situ measurements collected in the framework of the INMS, INSA and INDAAF projects, together with published data and modelling outputs to estimate a complete nitrogen balance for Lake Victoria and its catchment for 2018. This calculation includes the quantification of organic nitrogen in rain and soil solutions, which is rarely quantified despite being an important source of nitrogen for African ecosystems rarely quantified.

Claire Delon (Laero, CNRS/UT3-UPS), the INSA project coordinator, Corinne Galy-Lacaux (Laero, CNRS/UT3-UPS), also on the INSA coordination team and coordinator of the INDAAF network, also attended the conference.


Bakayoko, A., C. Galy-Lacaux, V. Yoboué, J. E. Hickman, F. Roux, E. Gardrat, F. Julien and C. Delon (2021). Dominant contribution of nitrogen compounds in precipitation chemistry in the Lake Victoria catchment (East Africa). Environmental Research Letters 16, 045013.

Donnou, H.E.V., A.B. Akpo, M. Ossohou, C. Delon, V. Yoboué, D. Laouali, M. Ouafo-Leumbe, P.G. Van Zyl, O. Ndiaye, E. Gardrat, M. Dias-Alves, and C. Galy-Lacaux (2024). Under review for Atmospheric Chemistry and Physics (ACP), preprint available at:

Kassamba-Diaby, M.L., C. Galy-Lacaux, V. Yoboué, J.E. Hickman, C. Mouchel-Vallon, K. Jaars, S. Gnamien, R. Konan, E. Gardrat and S. Silué (2023). The Chemical Characteristics of Rainwater and Wet Atmospheric Deposition Fluxes at Two Urban Sites and One Rural Site in Côte d’Ivoire. Atmosphere. 14: 809.

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