A Vertically Resolved Canopy Improves Chemical Transport Model Predictions of Ozone Deposition to North Temperate Forests
Year: 2024
Type: article
Abstract: Dry deposition is the second largest tropospheric ozone (O 3 ) sink and occurs through stomatal and nonstomatal pathways. Current O 3 uptake predictions are limited by the simplistic big‐leaf schemes commonly used in chemical transport models (CTMs) to parameterize deposition. Such schemes fail to reproduce observed O 3 fluxes over terrestrial ecosystems, highlighting the need for more realistic treatment of surface‐atmosphere exchange in CTMs. We address this need by linking a resolved canopy model (1D Multi‐Layer Canopy CHemistry and Exchange Model, MLC‐CHEM) to the GEOS‐Chem CTM and use this new framework to simulate O 3 fluxes over three north temperate forests. We compare results with in situ measurements from four field studies and with standalone, observationally constrained MLC‐CHEM runs to test current knowledge of O 3 deposition and its drivers. We show that GEOS‐Chem overpredicts observed O 3 fluxes across all four studies by up to 2×, whereas the resolved‐canopy models capture observed diel profiles of O 3 deposition and in‐canopy concentrations to within 10%. Relative humidity and solar irradiance are strong O 3 flux drivers over these forests, and uncertainties in those fields provide the largest remaining source of model deposition biases. Flux partitioning analysis shows that: (a) nonstomatal loss accounts for 60% of O 3 deposition on average; (b) in‐canopy chemistry makes only a small contribution to total O 3 fluxes; and (c) the CTM big‐leaf treatment overestimates O 3 ‐driven stomatal loss and plant phytotoxicity in these temperate forests by up to 7×. Results motivate the application of fully online vertically explicit canopy schemes in CTMs for improved O 3 predictions.
DOI: 10.1029/2024jd042092
Institutions: University of Minnesota, Purdue University West Lafayette, Colorado State University, Wageningen University & Research, European Centre for Medium-Range Weather Forecasts, Tofwerk (Switzerland), University of Wisconsin–Madison, University of Wisconsin–Eau Claire, Harvey Mudd College, National Institute of Standards and Technology, Engineering Laboratory, Aerodyne Research, Institute of Arctic and Alpine Research, University of Colorado Boulder
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,880
Awards: G1124323555, G1386488896, Collaborative Research: Forest-Atmosphere Volatile Organic Compound (VOC) Exchange for a Coniferous Ecosystem - Closing the Flux Budget, G240524355, G4071522219, Leaf-level to Canopy NOx and Ozone Exchanges at University of Michigan Biological Station (UMBS) during PHotochemistry, Emissions, and Transport (PROPHET) 2016, G7106711733, Closing the energy balance gap at scale, Chequamegon Heterogeneous Ecosystem Energy-balance Study Enabled by a High-density Extensive Array of Detectors, Collaborative Research: Forest-Atmosphere Volatile Organic Compound (VOC) Exchange for a Coniferous Ecosystem - Closing the Flux Budget
OpenAlex ID: W4405535314