Influence of plant ecophysiology on ozone dry deposition: comparing between multiplicative and photosynthesis-based dry deposition schemes and their responses to rising CO 2 level

[摘要] Dry deposition is a key process for surface ozone(O 3 ) removal. Stomatal uptake is a major component of O 3 drydeposition, which is parameterized differently in current land surfacemodels and chemical transport models. We developed and used a standaloneterrestrial biosphere model, driven by a unified set of prescribedmeteorology, to evaluate two widely used dry deposition modeling frameworks,Wesely (1989) and Zhang et al. (2003), with different configurations ofstomatal resistance: (1) the default multiplicative method in the Weselyscheme (W89) and Zhang et al. (2003) scheme (Z03), (2) the traditionalphotosynthesis-based Farquhar–Ball–Berry (FBB) stomatal algorithm, and (3) theMedlyn stomatal algorithm (MED) based on optimization theory. We found thatusing the FBB stomatal approach that captures ecophysiological responses toenvironmental factors, especially to water stress, can generally improve thesimulated dry deposition velocities compared with multiplicative schemes.The MED stomatal approach produces higher stomatal conductance than FBB andis likely to overestimate dry deposition velocities for major vegetationtypes, but its performance is greatly improved when spatially varying slopeparameters based on annual mean precipitation are used. Large discrepancieswere also found in stomatal responses to rising CO 2 levels from 390to 550 ppm: the multiplicative stomatal method with an empirical CO 2 response function produces reduction ( − 35 %) in global stomatalconductance on average much larger than that with the photosynthesis-basedstomatal method ( − 14 %–19 %). Our results show the potential biases inO 3 sink caused by errors in model structure especially in the Weselydry deposition scheme and the importance of using photosynthesis-basedrepresentation of stomatal resistance in dry deposition schemes under achanging climate and rising CO 2 concentration.

[学科分类] 大气科学