title: A fully integrated isoprenoid emissions model coupling emissions to photosynthetic characteristics.
abstract: The lack of a mechanistic basis has hampered modelling isoprene emission responses to environmental drivers, in particular the simulation of isoprene emissions under different CO₂ concentrations. Here, we advance previous semi-mechanistic model formulations by introducing a model that explicitly links electron availability for other purpose than carbon assimilation (or available energy for secondary metabolism processes; supply-constraint) and enzyme activity (capacity-constraint) to emissions. We furthermore investigate the sensitivity of the model to variations in photosynthetic and emission-specific parameters. By comparing species-specific simulations with experimental data, we demonstrate that differences in photosynthetic characteristics can explain inter-species differences in emissions. Interestingly, the seasonal development of emissions could also be explained to some degree by the change in energy supply from photosynthesis throughout the season. In addition, we show that the principal responses are not limited to isoprene but can be formulated to describe the emission of other light-dependent volatile species. The proposed model is suitable for implementation into regional and global models, particularly those that already provide species-specific photosynthesis estimates.
authors.affiliation: Institute for Advanced Sustainability Studies (IASS), Berliner Str. 130, Potsdam, 14467, Germany; Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research (IMK-IFU), Kreuzeckbahnstraße 19, Garmisch-Partenkirchen, 82467, Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Grote
authors.forename: Catherine
authors.initials: C
authors.lastname: Morfopoulos
authors.forename: Ülo
authors.initials: Ü
authors.lastname: Niinemets
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Sun
authors.forename: Trevor F
authors.initials: TF
authors.lastname: Keenan
authors.forename: Federica
authors.initials: F
authors.lastname: Pacifico
authors.forename: Tim
authors.initials: T
authors.lastname: Butler
mesh_terms: D002070:Butadienes; D002245:Carbon Dioxide / Q000737:chemistry; D003198:Computer Simulation; D004777:Environment; D045782:Hemiterpenes / Q000096:biosynthesis*; D008027:Light; D008962:Models, Theoretical; D010420:Pentanes; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000378:metabolism; D018521:Plant Physiological Phenomena; D064210:Secondary Metabolism; D013045:Species Specificity
chemical_list: D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; C005059:isoprene; D002245:Carbon Dioxide
keywords: biogenic emission modelling; environmental sensitivity; model evaluation; photosynthetic electron transport.