Simulation of ozone-vegetation coupling and feedback in China using multiple ozone damage schemes

Abstract

As a phytotoxic pollutant, surface ozone (O3) not only affects plant physiology but also influences meteorological fields and air quality by altering leaf stomatal functions. Previous studies revealed strong feedbacks of O3-vegetation coupling in China but with large uncertainties due to the applications of varied O3 damage schemes and chemistry-vegetation models. In this study, we quantify the O3 vegetation damage and the consequent feedbacks to surface meteorology and air quality in China by coupling two O3 damage schemes (S2007 vs. L2013) into a fully coupled regional meteorology-chemistry model. With different schemes and damaging sensitivities, surface O3 is predicted to decrease summertime gross primary productivity by 5.5g%-21.4g% and transpiration by 5.4g%-23.2g% in China, in which the L2013 scheme yields 2.5-4 times of losses relative to the S2007 scheme. The damage to the photosynthesis of sunlit leaves is g1/4g2.6 times that of shaded leaves in the S2007 scheme but shows limited differences in the L2013 scheme. Though with large discrepancies in offline responses, the two schemes yield a similar magnitude of feedback to surface meteorology and O3 air quality. The O3-induced damage to transpiration increases national sensible heat by 3.2-6.0gWm-2 (8.9g% to 16.2g%), while reducing latent heat by 3.3-6.4gWm-2 (-5.6g% to-17.4g%), leading to a 0.2-0.51g°C increase in surface air temperature and a 2.2g%-3.9g% reduction in relative humidity. Meanwhile, surface O3 concentrations on average increase by 2.6-4.4gμgm-3, due to the inhibitions of stomatal uptake and the anomalous enhancement in isoprene emissions, the latter of which is attributed to the surface warming by O3-vegetation coupling. Our results highlight the importance of O3 control in China due to its adverse effects on ecosystem functions, global warming, and O3 pollution through O3-vegetation coupling.