Giulia Salmaso, Researcher at CNR-ISAC, Bologna

03/02/2026 – 11:00

CNR-ISAC, Bologna meeting room and ONLINE

Abstract

Vegetated canopies and their exchanges of carbon, momentum, energy, and mass with the Atmospheric Boundary Layer (ABL) play a fundamental role in the Earth’s climate system. Traditionally, and due to past limitations in computing power and numerical resolution, vegetated canopies have been represented in Earth system models (ESMs) by adjusting the surface roughness parameter (z₀), with different values used to characterize various types of vegetated canopies. Such an approach is appropriate when the first computational grid point lies well above the vegetated canopy top, where the turbulent flow is expected to have recovered Inertial Sublayer (ISL) characteristics. In this regime, turbulence is characterized by the ratio of the distance above the canopy displacement height (z-d) to the Obukhov length (L), which accounts for thermal stratification, and Monin–Obukhov Similarity Theory (MOST) provides the basis for parameterizing turbulent statistics. With increasing model resolution, however, the first vertical grid level in many ESMs now lies only a few meters above the surface, often within the Roughness Sublayer (RSL). In this region, additional canopy-related length scales become important, and MOST is no longer strictly valid. At present, several corrections exist to facilitate the parameterization of the RSL characteristic of homogeneous canopies in ESMs of different resolutions. However, much less is known about turbulent flow characteristics over sparse or heterogeneous canopies containing large openings. Addressing this gap is essential for improving canopy parameterizations in ESMs. Here, this gap is addressed by performing high-resolution Large-eddy Simulations (LES) of atmospheric boundary-layer flow over heterogeneous canopies with open spaces (gaps) ranging in size from ~ m. Simulations are conducted under neutral stratification with uniform under-canopy roughness and geostrophic forcing. Results highlight the role of canopy heterogeneity in shaping mean and turbulent momentum transport, underscoring the need for improved canopy parameterizations in ESMs across model resolutions.Vegetated canopies and their exchanges of carbon, momentum, energy, and mass with the Atmospheric Boundary Layer (ABL) play a fundamental role in the Earth’s climate system. Traditionally, and due to past limitations in computing power and numerical resolution, vegetated canopies have been represented in Earth system models (ESMs) by adjusting the surface roughness parameter (z₀), with different values used to characterize various types of vegetated canopies. Such an approach is appropriate when the first computational grid point lies well above the vegetated canopy top, where the turbulent flow is expected to have recovered Inertial Sublayer (ISL) characteristics. In this regime, turbulence is characterized by the ratio of the distance above the canopy displacement height (z-d) to the Obukhov length (L), which accounts for thermal stratification, and Monin–Obukhov Similarity Theory (MOST) provides the basis for parameterizing turbulent statistics. With increasing model resolution, however, the first vertical grid level in many ESMs now lies only a few meters above the surface, often within the Roughness Sublayer (RSL). In this region, additional canopy-related length scales become important, and MOST is no longer strictly valid. At present, several corrections exist to facilitate the parameterization of the RSL characteristic of homogeneous canopies in ESMs of different resolutions. However, much less is known about turbulent flow characteristics over sparse or heterogeneous canopies containing large openings. Addressing this gap is essential for improving canopy parameterizations in ESMs. Here, this gap is addressed by performing high-resolution Large-eddy Simulations (LES) of atmospheric boundary-layer flow over heterogeneous canopies with open spaces (gaps) ranging in size from ~ m. Simulations are conducted under neutral stratification with uniform under-canopy roughness and geostrophic forcing. Results highlight the role of canopy heterogeneity in shaping mean and turbulent momentum transport, underscoring the need for improved canopy parameterizations in ESMs across model resolutions.

Bio

Giulia is a research scientist at CNR–ISAC in Bologna. Before joining ISAC, she completed her PhD at the University of Utah (Salt Lake City, USA), where she investigated the influence of heterogeneity in vegetated canopies using Large-Eddy Simulations (LES). Her academic training is in hydrology and hydrodynamics, having earned a M.S. in Civil and Environmental Engineering at the University of Padova (Italy). Her current work seeks to contribute to ongoing efforts to connect microscale canopy processes with climate-scale modeling, aiming to improve the representation of surface heterogeneities in Earth System Models (ESMs).

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