Microclimate variations in the roughness sublayer above European forests: assessing theories using ICOS network data
Abstract
(300 words max) Forests are aerodynamically rough surfaces above which turbulent exchange is enhanced, generating smaller vertical gradients in windspeed and air temperature than those predicted by the Monin-Obukhov Similarity Theory (MOST). Roughness sublayer (RSL) corrections, based on canopy structure, have been proposed to account for this enhancement in turbulent exchange, but evaluation of these RSL corrections above a range of forest types is still lacking. In this study, we mobilised multiyear datasets of canopy structure, turbulent fluxes and microclimate gradients from the ICOS European network to evaluate two widely-used RSL corrections in a range of climates, forest structures and atmospheric conditions. As expected, observed windspeed gradients above these forest sites were smaller than MOST predictions. The two RSL corrections improved the windspeed gradient predictions with similar accuracy, irrespective of atmospheric stability conditions. The need of RSL corrections for predicting air temperature gradients above forests was more contrasted than for windspeed, and depended on the site and the atmospheric stability conditions. Overall, the RSL corrections at canopy height remained relatively small, around 0.5°C for air temperature and 0.5 m s -1 for windspeed on average, and were most pronounced under stable atmospheric conditions. Based on the evaluation of the simplifying assumptions behind each RSL correction, we built recommendations to implement those corrections in models. We also discussed the potential impact of wind sensor positions to estimate aerodynamic parameters needed to apply MOST and RSL corrections and provide recommendations for improvement of the ICOS network. Our results highlight the difficulty to estimate displacement height and relate it to canopy structure, and question the idea that the drag coefficient does not change with leaf area or clumping.
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BibTeX
@article{bouwen2026microclimate,
title = {{Microclimate variations in the roughness sublayer above European forests: assessing theories using ICOS network data}},
author = {Klara Bouwen and Yves Brunet and Sébastien Lafont and Jean-Christophe Domec and Marie Charru and Christophe Chipeaux and Daniel Berveiller and Matthias Cuntz and Guillaume Simioni and Pasi Kolari and Maarten Krol and Michiel van der Molen and Anne Klosterhalfen and Alexander Knohl and Jérôme Ogée},
journal = {Agricultural and Forest Meteorology},
year = {2026},
month = oct,
doi = {10.1016/j.agrformet.2026.111442},
url = {https://hal.inrae.fr/hal-05841080v1},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Microclimate variations in the roughness sublayer above European forests: assessing theories using ICOS network data
AU - Klara Bouwen
AU - Yves Brunet
AU - Sébastien Lafont
AU - Jean-Christophe Domec
AU - Marie Charru
AU - Christophe Chipeaux
AU - Daniel Berveiller
AU - Matthias Cuntz
AU - Guillaume Simioni
AU - Pasi Kolari
AU - Maarten Krol
AU - Michiel van der Molen
AU - Anne Klosterhalfen
AU - Alexander Knohl
AU - Jérôme Ogée
PY - 2026
DA - 2026/10/27
JO - Agricultural and Forest Meteorology
DO - 10.1016/j.agrformet.2026.111442
UR - https://hal.inrae.fr/hal-05841080v1
AB - (300 words max) Forests are aerodynamically rough surfaces above which turbulent exchange is enhanced, generating smaller vertical gradients in windspeed and air temperature than those predicted by the Monin-Obukhov Similarity Theory (MOST). Roughness sublayer (RSL) corrections, based on canopy structure, have been proposed to account for this enhancement in turbulent exchange, but evaluation of these RSL corrections above a range of forest types is still lacking. In this study, we mobilised multiyear datasets of canopy structure, turbulent fluxes and microclimate gradients from the ICOS European network to evaluate two widely-used RSL corrections in a range of climates, forest structures and atmospheric conditions. As expected, observed windspeed gradients above these forest sites were smaller than MOST predictions. The two RSL corrections improved the windspeed gradient predictions with similar accuracy, irrespective of atmospheric stability conditions. The need of RSL corrections for predicting air temperature gradients above forests was more contrasted than for windspeed, and depended on the site and the atmospheric stability conditions. Overall, the RSL corrections at canopy height remained relatively small, around 0.5°C for air temperature and 0.5 m s -1 for windspeed on average, and were most pronounced under stable atmospheric conditions. Based on the evaluation of the simplifying assumptions behind each RSL correction, we built recommendations to implement those corrections in models. We also discussed the potential impact of wind sensor positions to estimate aerodynamic parameters needed to apply MOST and RSL corrections and provide recommendations for improvement of the ICOS network. Our results highlight the difficulty to estimate displacement height and relate it to canopy structure, and question the idea that the drag coefficient does not change with leaf area or clumping.
SN - 0168-1923
ER -