General comment:

This paper presents ozone and water-stress impact on wheat productivity under current and future climate scenarios in India to highlight the importance of the irrigation for crop production. The effects of ozone stress on the yield under the different humidity and climate conditions were quantified based on WRF model simulation, and their sensitivities influenced by climate and plant were discussed. Overall, the study addresses a significant gap in the understanding of the agricultural impact of ozone and its coupling with water stress in India, a region experiencing increasing ozone pollution. The conception is interesting and impressive. However, authors only discuss the average result of ozone impact during the study period, the spatial and temporal variations of ozone impact are not included, which need more comprehensive investigations. Additionally, the method introduction should be more specific and detailed.

The following changes should be made to improve the manuscript with respect to clarity, information content and thus value to the reader.

Specific questions/issues:

Table 1： Temperature（°c）→℃

Line 192: How to calculate the RstoH2O? based on Gsto?

Line 199-200: “K𝑦 is the crop-specific yield response factor assumed to be 1.15 for the whole growing season” Are there any difference for the response factor of different wheat cultivars? as the different stomatal sensitivity and gmax.

Table 2: Canopy height: How about the variability of canopy height? Canopy height depends on wheat growth, and it increases from 0 m after sowing to the maximum height (~ 1 m) at the end of growth stage. Why do you choose the maximum height as canopy height in the simulation? How does the height affect the simulation? (Crop height: https://doi.org/10.1007/s12524-024-02028-4)

Section 2: The method of chemistry simulation and evaluation in WRF model should be added, as ozone concentration is critical to ozone uptake and impact.

Section 3.1: Although phenology is crucial for leaf stomatal conductance and ozone uptake, the magnitude of ozone uptake is the most important for the accurate evaluation of ozone impact on yield loss. How do you assess the uncertainty of modelled POD?

Section 3.2: What is the definition of water-stress condition? Are there any indexes or indicators to measure the humidity? As POD is a cumulative metric for the whole period of wheat growth, how do you simulate the cumulative ozone flux under two humidity conditions? How about the spatial distribution of O3-related yield loss and WSRYL?

Line 289-292: “Under rainfed conditions, mean O3RYL was projected to be negligible (0.6%), significantly lower than the mean O3RYL when no water-stress is assumed under irrigation (10.7% with a range of 4.8-15.4%). This demonstrates the importance of irrigation for wheat production in India and highlights the substantial influence on the yield of O3 for irrigated wheat.” What are the main pathways through which the irrigation could reduce ozone impact? and their relative contributions?

Lines 328-330: “The current climate represents the lowest mean O3, suggesting O3, rather than other environmental conditions that might influence sensitivity to O3, is the most important factor in determining O3-induced yield loss.” Please rephrase this sentence, it’s a bit hard to understand. Whose sensitivity do the environmental conditions influence?

Lines 350-355: “Whilst the RCP4.5 scenario sees a global reduction in [O3] due to pollution regulation, the South Asian region is an exception to this rule, where [O3] continues to increase at a similar rate as occurred in previous decades (Tai and Martin, 2017). RCP8.5 projects a worldwide increase in [O3] due to the lack of regulation of precursor emissions except in parts of the US, East and Southeast Asia (Tai and Martin, 2017). Therefore, mean [O3] during the growing season is lowest in the current climate at 48.6ppb but similar, at least in South Asia, in both the RCP4.5 and RCP8.5 scenarios (60.5ppb and 59.7ppb respectively; Table 1)” Ozone concentration continues to increase at a similar rate under the RCP4.5 emission scenario, and RCP8.5 also will lead a worldwide increase to ozone due to the lack of emission regulation. So why are ozone concentrations at the similar levels under RCP4.5 and RCP 8.5? and ozone in the RCP4.5 is even slightly higher than that in the RCP8.5.

General Comments:

The paper describes model study to assess the inter-related impacts of ozone- and water-stress-induced yield losses in two wheat cultivars in an agricultural region in India. The authors model ozone fluxes into the plant using WRF-Chem simulations of current and future surface ozone and meteorological conditions, using the RCP4.5 and RCP8.5 future scenarios. The study finds that under rainfed conditions, water stress induces stomatal closure, thus protecting plants from ozone uptake and minimizing ozone-induced yield losses, though water-stress-induced losses remain. However, under irrigated conditions, stomatal opening sustains high ozone uptake, resulting in substantial ozone-induced yield losses that largely offset reductions in water-stress-induced losses. The authors advocate for more research into ozone-water effects in crops and suggest potential changes in irrigation management to find practicable strategies for mitigating wheat yield losses due to both water stress and ozone.

Specific Comments:

Section 2.3-2.4: I have seen some studies (not treating wheat) that suggest the timing of ozone exposure and water stress may be important in predicting how they interact to impact plant damages (e.g., Matyssek 2006; https://doi.org/10.1055/s-2005-873025). For example, if ozone exposure preceding drought damages stomatal regulation, this could impact stomatal response to VPD under water stress. Can you please expand on whether the DO₃SE model has any mechanism to test this type of asynchrony in drought or ozone exposure leading to injury or impairment of stomatal regulation? Could this be applied in such a study?

Section 2.3: Are there any data to validate the DO₃SE derived ozone fluxes, even at other field sites? What is the uncertainty in model derived fluxes?

Equation 4: Some more clarification would be helpful. Where does the factor of 3.85, for example, come from? Can you provide a reference for this?

Line 273-76/Figure 3: It is compelling to see a plot of WRF vs site temperatures over the growing season. The authors should expand a bit on how they expect modeled meteorology to impact their conclusions. Does WRF under-predict humidity for example? I think it would also be very compelling to see a similar plot of modeled and observed ozone at this site, since according to the authors, this site was chosen in part due to availability of ozone data (L116-18). 

Technical Corrections:

L26-7: O3-RYL is given a slightly different meaning later on (see L287)

L109: POD-SEPC acronym not previously defined

L189: Symbol of Et is elsewhere fully capitalized