Model and Observation for surface-atmosphere interactions over heterogeneous landscape: MOSAI project
Modélisation et observation des interactions surface-atmosphère en milieu hétérogène : projet MOSAI
Lohou, F. ; Lothon, M. ; Bastin, S. ; Brut, A. ; Canut, Guylaine ; Cohard, J. -M. ; Cheruy, F. ; Couvreux, Fleur ; Dupont, S. ; Lafont, S. ; Roehrig, Romain ; Román-Cascón, C. ; Yagüe, C. ; Bernard, E. ; Boone, Aaron ; Dupont, J. -C. ; Feofilov, A. ; Fernandes, R. ; Grulois, M. ; Jomé, M. ; Maison, A. ; Zouzoua, M.
Année de publication
2025
The land surface impacts the atmosphere from daily to seasonal time scales. An accurate assessment of the land-atmosphere exchanges, and their correct representation in surface schemes, are therefore essential for weather and climate forecasts. However, Earth System and Numerical Weather Prediction models often have large biases in their representation of surface-atmosphere fluxes when compared to observations. The Model and Observation for Surface-Atmosphere Interactions over heterogeneous landscape (MOSAI) project aims at improving modeling and estimating surface fluxes, with a focus on the impact of surface heterogeneity. First of all, a fair evaluation of the simulated land-atmosphere interactions in the models needs dedicated measurements and appropriate methods. Thus, the first MOSAI objective is to establish the uncertainty and representativity of land-atmosphere exchanges measured over a heterogeneous landscape. The second MOSAI objective addresses some simplifications and hypotheses in the coupling between land and atmospheric models, and their impacts on the simulated land-atmosphere exchanges. Then, the third scientific objective is to propose and test observation-model comparison methods that go further than point-to-point, time, or case-study comparisons. The MOSAI strategy leans on permanent surface energy balance stations belonging to research infrastructure and on devoted experimental campaigns in different heterogeneous landscapes. A wide range of models are also involved, from large-eddy simulation to climate models. This article will start with an overview of the impact of heterogeneous surfaces on the atmospheric boundary layer, on the difficulty of measuring surface fluxes over heterogeneous landscape, and on the simplifications of surface-atmosphere interactions over heterogeneous landscape employed by numerical models. Then, the objectives and strategy of the MOSAI project will be presented, illustrated by preliminary results.</div>
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