the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 06 Oct 2023
Evapotranspiration evaluation by 3 different protocols on a large green roof in the greater Paris area
Pierre-Antoine Versini
Leydy Alejandra Castellanos-Diaz
David Ramier
Ioulia Tchiguirinskaia
Abstract. Nature-Based Solutions have appeared as relevant solutions to mitigate urban heat islands. To improve our knowledge on the assessment of this ecosystem service and the related physical processes (evapotranspiration), monitoring campaigns are required. It was the objective of several experiments carried out on the Blue Green Wave, a large green roof located at Champs-sur-Marne (France). Three different protocols were implemented and tested to assess the evapotranspiration flux at different scales. The first one was based on the surface energy balance (large scale). The second one was carried out by an evapotranspiration chamber (small scale). The third one was based on the water balance evaluated during dry periods (punctual scale). In addition to these evapotranspiration estimates, several hydro-meteorological variables (especially temperature) were measured. Related data and Python programs providing preliminary elements of analysis and graphical representation have been made available. They illustrate the space-time variability of the studied processes regarding their observation scale. The dataset (Versini et al., 2023a) is available here: https://doi.org/10.5281/zenodo.8064053
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Pierre-Antoine Versini et al.
Status: open (extended)
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RC1: 'Comment on essd-2023-324', Anonymous Referee #1, 06 Nov 2023
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This manuscript presents in detail the materials and methods utilised in the production of a comprehensive evapotranspiration (ET) monitoring dataset. The data acquisition and interpretation methods are well outlined, with some nice reflection on data quality during the presented example in section 3.3. The data, already available via doi, is a welcome addition to the field.
Specific Comments:
- I continue to have reservations about the sourcing of key meteorological data from some 50 km away from the test location (L372). The manuscript stresses the importance of understanding ET processes to mitigate UHI effects. However, there is no mention of the micro-meteorological phenomena that help to create an UHI effect which can occur at much smaller scales than 50 km. Please demonstrate the insensitivity of final ET values to these meteorological data or otherwise more adequately caution the reader of their influence on the results.
- I don’t believe the presentation of the python scripts (section 3.2) to be helpful in demonstrating the importance/novelty of the dataset. I can appreciate these scripts are provided to aid accessibility, but this content is more appropriate in the README file that accompanies the data in the open access repository. Please consider removing and replacing with greater comparison of the obtained ET values from the three methods (where appropriate).
Citation: https://doi.org/10.5194/essd-2023-324-RC1 -
AC1: 'Reply on RC1', Pierre-Antoine Versini, 17 Nov 2023
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Thanks a lot for these positive and constructive comments.
Comment 1: Indeed, micro-meteorological phenomena can have some influence on UHI creation. Wind only intervenes directly in the large scale evapotranspiration assessment by Surface Energy Balance, and more precisely in the sensible heat flux estimated by scintillometer. To understand the variables that most impact the iterative process of 𝑄h calculation (Eq. 10, 11, 12), a sensitivity analysis through a Latin Hypercube Sampling (LHS) was conducted (see Castellanos, 2022). The Pearson’s Correlation coefficient used as a sensitivity index in this analysis showed that the wind speed 𝑈 was moderately correlated to 𝑄h (0.35). Moreover, for these particular cases, the monitoring campaigns occurred in relative no-wind conditions, for which we can assume very few differences between local data and Meteo France data. Note that, since these campaigns occurred, some anemometers have been implemented on the ENPC campus to have local wind measurments. These details will be added in the revised manuscript.
Commetn 2: As mentioned in the guidelines for authors, “all material required to understand the essential aspects of the paper such as experimental methods, data, and interpretation should preferably be included in the main text”. In consequence the description of the python scripts could be transferred in an Appendix as advised by HESSD. These descriptions contain some elements to explain the provided scripts to read and analyze the data, and how the equations presented in the manuscript are used. In return, the comparison of the obtained ET values can be extended (by presenting the spatial variability captured by the water content sensors for instance).
Citation: https://doi.org/10.5194/essd-2023-324-AC1
Pierre-Antoine Versini et al.
Pierre-Antoine Versini et al.
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