Predicting and partitioning ozone fluxes to maize crops from sowing to harvest: the Surfatm-O<sub>3</sub> model

Abstract

Abstract. Terrestrial ecosystems represent a major sink for ozone (O 3 ) and also a critical control of tropospheric O 3 budget. However, due to its deleterious effects, plant functioning is affected by the ozone absorbed. It is thus necessary to both predict total ozone deposition to ecosystems and partition the fluxes in stomatal and non-stomatal pathways. The Surfatm-O 3 model was developed to predict ozone deposition to agroecosystems from sowing to harvest, taking into account each deposition pathways during bare soil, growth, maturity, and senescence periods. An additional sink was added during senescence: stomatal deposition for yellow leaves, not able to photosynthesise but transpiring. The model was confronted to measurements performed over three maize crops in different regions of France. Modelled and measured fluxes agreed well for one dataset for any phenological stage, with only 4 % difference over the whole cropping season. A larger discrepancy was found for the two other sites, 15 % and 18 % over the entire study period, especially during bare soil, early growth and senescence. This was attributed to site-specific soil resistance to ozone and possible chemical reactions between ozone and volatile organic compounds emitted during late senescence. Considering both night-time and daytime conditions, non-stomatal deposition was the major ozone sink, from 100 % during bare soil period to 70-80 % on average during maturity. However, considering only daytime conditions, especially under optimal climatic conditions for plant functioning, stomatal flux could represent 75 % of total ozone flux. This model could improve estimates of crop yield losses and projections of tropospheric ozone budget.

Dry deposition of nitrogen compounds (NO<sub>2</sub>, HNO<sub>3</sub>, NH<sub>3</sub>), sulfur dioxide and ozone in west and central African ecosystems using the inferential method

“…In fact, in this model of deposition, the NO 2 V d is parameterized similar to the one of O 3 due to similar behavior for a variety of conditions and the importance of their stomatal uptake (Zhang et al, 2002a). However, some studies pointed out the importance of the non-stomatal deposition fluxes in the case of O 3 Stella et al, 2011). NH 3 V d is similar to SO 2 but slightly higher due to its higher molecular diffusivity.…”

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

“…Whether it is possible to separate the components of R ns (R c2 -external surfaces; R c3 -soil; R c4 -in-canopy chemistry) depends on the nature of the measurement site and canopy, and there are some models available based on measurements over bare soil, senescent vegetation and in-canopy chemistry (Launiainen et al, 2013;Fares et al, 2013bFares et al, , 2012Büker et al, 2012;Tuzet et al, 2011;Stella et al, 2011). Many research groups have taken this approach, and Table 1 provides a summary of some of the different estimates of the values for R ns in the literature.…”

Measurements of nitrogen oxides and ozone fluxes by eddy covariance at a meadow: evidence for an internal leaf resistance to NO<sub>2</sub>

“…It comprises one vegetation layer and one soil layer. This model was initially developed to simulate the ammonia exchange, it was validated over grasslands by Personne et al (2009), and it was recently adapted to estimate O 3 deposition to several maize crops by Stella et al (2011b). In the following, we will only focus on the specific resistances to NO 2 and O 3 deposition.…”

“…In order to investigate the processes governing the exchanges of NO 2 and O 3 , we used the Surfatm model developed to simulate exchanges of heat and pollutant between the atmosphere and the vegetation Stella et al, 2011b). It is a multi-resistance soil-vegetationatmosphere transfer (SVAT) model which couples (i) a trace gas exchange model and (ii) an energy budget model allowing to estimate the temperature and humidity of the leaves and of the soil to calculate the resistances to trace gas exchange.…”