the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 10 Jul 2026
Multi-year convection-permitting irrigation impacts across the European continent
Abstract. Irrigation representation in weather and climate modeling is advancing and becoming more relevant. Global, regional and local studies that included irrigation in Earth system models already demostrated the effects of irrigation in different variables. Some regional and local simulations have studied the irrigation impact in some parts of Europe with simulations limited to the duration of one growing season. Therefore, long-term irrigation simulations that cover the whole European continent are still missing. This study quantifies the long-term impact of irrigation on surface and atmospheric variables over the EURO-CORDEX domain using convection-permitting ICON simulations that cover a period of 12 years. Our findings indicate that the magnitude of the irrigation impact is limited by the irrigated region and the year of study in the EURO-CORDEX domain, showing that the land-atmosphere coupling is key to determine the irrigation effects. For instance, the cold and wet summer of 2017 in south Europe weaked the irrigation cooling in the Alps. In contrast, the heat wave of 2018 in Central Europe enabled the influence of irrigation on surface variables in this region.
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Status: final response (author comments only)
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RC1: 'Comment on egusphere-2026-3354', Amen Al-Yaari, 20 Aug 2026
- AC1: 'Reply on RC1', Jane Roque, 30 Aug 2026
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RC2: 'Comment on egusphere-2026-3354', Anonymous Referee #2, 27 Aug 2026
This study by Roque and Valmassoi investigates the impacts of irrigation across the European continent using convection-permitting experiments with ICON. The authors examine irrigation-induced changes in soil moisture, latent and sensible heat fluxes, and temperature. The impacts of irrigation on selected heatwave events are also explored. Overall, this is an interesting topic, and the ICON experiments can help improve our understanding of the impacts of land use on hydroclimate in Europe. However, the manuscript is not well written, and the methodology and results require significant improvement.
Major Comments:
1) The authors should improve the English throughout the manuscript. For instance, there are many writing issues on the first page alone. The methodology section is also poorly structured. I list specific issues below in the Specific Comments section.
2) The motivation for using convection-permitting experiments is unclear. The authors do not explain why they chose the convection-permitting scale, which is computationally expensive. What added value does this model configuration provide in this study? The analysis of the model output focuses primarily on several near-surface variables. It would be more meaningful to include analysis of precipitation.
3) The model evaluation is based on the ICON-DREAM reanalysis, which also provides the boundary conditions for the irrigation experiments. The authors should consider using other observation-based datasets to assess model performance.
4) The irrigation scheme “integrates irrigation water into grid-scale precipitation before it is passed to the land surface.” This is a typical representation of sprinkler irrigation. It is unclear why the authors chose this irrigation method. Can sprinkler irrigation adequately represent actual irrigation practices across Europe?
5) Although the title refers to irrigation impacts “across the European continent,” the analysis focuses only on three subregions: the Alps, the Mediterranean, and Mid-Europe. According to the irrigation map, there are also large irrigated areas in the Iberian Peninsula. Why were these areas not considered?
Specific Comments:
L1: Revise “advancing and becoming more relevant.”
L4: Change “Therefore” to “However.”
L6: Spell out ICON or remove the acronym.
L10: It would be better to include a concluding sentence.
L12: Revise “The role of irrigation in research” to “Research on irrigation impacts.”
L17: “Biases”: biases in what?
L17: Revise “overcome this lack.”
L72: Why are evaporation sources discussed here?
L71: In the Methodology section, the authors should include a section describing the ICON model. Subsections 2.1 and 2.1.x should be at the same hierarchical level.
L173: Revise “Model discussion.”
L227: Use consistent formatting for the section title.
L240: I assume that the model uses negative values to represent upward fluxes. This convention should be clearly explained. The current figures show negative values for changes in LHF, which could be misleading because negative values are typically interpreted as a decrease in LHF.Citation: https://doi.org/10.5194/egusphere-2026-3354-RC2 - AC2: 'Reply on RC2', Jane Roque, 09 Sep 2026
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This study investigates the impacts of irrigation on the European climate using 3-km convection-permitting ICON simulations for 2010-2022. It examines how irrigation modifies temperature, humidity, surface energy fluxes, and heat-wave characteristics across different European regions. The manuscript is well written and well structured, and I have only a few minor concerns that I would like the authors to clarify.
-The irrigation prescription is idealized. The irrigation timing varies by region and crop. For example, the authors acknowledge that night irrigation is common in the Ebro basin, while their irrigation occurs at 05 UTC. This is not a minor uncertainty: the timing of irrigation controls the partitioning between evaporation, sensible heat, boundary-layer development, and potentially convection. At 3-km resolution, timing becomes particularly important because irrigation can influence the diurnal boundary layer. I would quantify the uncertainty in the magnitude of irrigation and uncertainty in the timing and diurnal distribution of irrigation, which can alter the atmospheric response even if the annual irrigation volume is correct.
-The paper uses maize as the representative crop while their irrigation map contains irrigated croplands generally, not maize-specific irrigated areas. So, there is a conceptual mismatch? Different European crops have varying rooting depths and seasonal water requirements, which can strongly influence the calculated RAW and, in turn, the irrigation volume.
-What is the actual irrigation water applied? Can the authors show the annual irrigation amount by region and compare with independent irrigation water use estimates? Otherwise, it is difficult to know whether the climate response is physically realistic.
-The irrigation water is sourced externally and is not subtracted from other water reserves. This means the experiment is adding water to the terrestrial system without accounting for river withdrawal, groundwater depletion, reservoir storage, etc. For an atmospheric irrigation-impact experiment, this can be acceptable if the purpose is specifically to isolate the atmospheric response to irrigation. Still, the paper sometimes discusses the results as if they represent realistic irrigation. The distinction needs to be much clearer.
-The paper uses Siebert et al. (2013). Does this mean that the experiment doesn’t capture the expansion of irrigation during the recent period? What about changes in crop type and irrigation technology?
-Does an irrigated grid cell become entirely “irrigated cropland”? At 3 km, many grid cells may contain cropland, forest, grassland, water, and non-irrigated agriculture. Replacing the land-cover class could introduce a land-use perturbation that is not irrigation alone.
-The paper validates the simulations against 3-hourly quality-controlled observations from ICON DREAM reanalysis. But ICON-DREAM is a reanalysis, not an observational dataset. More details are required on which observation network, stations, number of stations, spatial distribution, and whether the station observations are independent of the reanalysis.