the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Enhancing simulations of snowpack properties in land surface models with the Soil, Vegetation and Snow scheme v2.0 (SVS2)
Abstract. Snow microstructure—characterized by density, grain size, grain shape and arrangement—fundamentally determines snowpack macroscopic properties. Despite this critical role, many land surface models (LSMs) lack explicit representation of snow microstructure. This limitation has become increasingly critical as future spaceborne missions for snow water equivalent measurement demand advanced modelling systems capable of accurately estimating snowpack properties, including microstructure, across diverse climatic and vegetation regions. The Soil Vegetation and Snow (SVS) LSM, used by Environment and Climate Change Canada for operational land surface and hydrological predictions, has been substantially upgraded to address these challenges. SVS version 2.0 (SVS2) incorporates the detailed multilayer Crocus snowpack model, enabling distinct simulations of snowpack evolution in both open terrain and forested areas within each grid cell. Crocus within SVS2 has been upgraded from its original alpine design with three major enhancements to handle Canada’s varied snowpack conditions: an advanced albedo parameterization that accounts for spatial variability in light-absorbing particle deposition, new physical parameterizations tailored to Arctic snow characteristics, and a refined canopy model for forest environments. Significant improvements in simulations of near-surface density predictions are evident along a latitudinal transect from southern Quebec to the Canadian Arctic, while challenges remain in simulation of density and specific surface area in basal snow layers. SVS2 achieved substantial gains in snow melt-out timing accuracy, reducing prediction errors by over 50 % compared to the alpine Crocus version and surpassing two established snow reference products (ERA5-Land and ERA5-Crocus). These enhancements position SVS2 as a substantial advancement for future operational snow modeling applications across Canada.
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Status: open (until 16 Sep 2025)
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CEC1: 'Comment on egusphere-2025-3396 - No compliance with the policy of the journal', Juan Antonio Añel, 28 Jul 2025
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Dear authors,
Unfortunately, after checking your manuscript, it has come to our attention that it does not comply with our "Code and Data Policy".
https://www.geoscientific-model-development.net/policies/code_and_data_policy.htmlIn your Code and Data Availability section you state that "The SVS2 code for distributed applications will be soon made available on https://github.com/ECCC-ASTD-MRD/sps". Firstly, we can not accept statements on future availability of assets used in a manuscript. Our policy clearly states that all the code and data necessary to replicate a manuscript must be published openly and freely to anyone before submission. Therefore, your manuscript should have never been accepted for Discussions given such lack of compliance with the policy. Secondly, GitHub, which you reference several times in your manuscript, is not a suitable repository for scientific publication. GitHub itself instructs authors to use other long-term archival and publishing alternatives for purposes of scientific research.
Additionally, for part of the data used in your manuscript you cite websites that are not suitable repositories, such as ulaval.ca or nesdis.noaa.gov, or point to generic main pages that do not contain the specific data used in your work, but are portals to access generic data. You must store the specific data used in your work in suitable repositories according to our policy.
Therefore, the current situation with your manuscript is irregular. Please, publish all the code and data necessary to replicate your work in one of the appropriate repositories and reply to this comment with the relevant information (link and a permanent identifier for it (e.g. DOI)) as soon as possible, as we can not accept manuscripts in Discussions that do not comply with our policy.
Also, you must include a modified 'Code and Data Availability' section in any potentially reviewed manuscript, containing the information of the new repositories.
I must note that if you do not fix this problem, we cannot continue with the peer-review process or accept your manuscript for publication in our journal.
Juan A. Añel
Geosci. Model Dev. Executive EditorCitation: https://doi.org/10.5194/egusphere-2025-3396-CEC1 -
AC1: 'Reply on CEC1', Vincent Vionnet, 29 Jul 2025
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Dear Dr. Juan A. Añel,
Thank you very much for your detailed comments regarding our manuscript.Following your comments, we have initiated actions at the Meteorological Research Division of Environment and Climate Change Canada to release on Github the SVS2 code for distributed applications. A corresponding permanent repository will be created on Zenodo and the corresponding DOI will be cited in the 'Code and Data Availability' section of our manuscript.
In a Zenodo repository, all the observation datasets used in the results section will be made publicly available as well as simulation configurations, and the scripts and extracts of simulation outputs used to generate the results and figures of our manuscript. The corresponding DOI will be cited in the 'Code and Data Availability' section of our manuscript.
We expect the Zenodo repositories to be available by August 8th. We will then post the corresponding information in this discussion to make sure that the peer-review process can continue.
Thank you very much for your time and consideration.
Best regards,
Vincent Vionnet
Citation: https://doi.org/10.5194/egusphere-2025-3396-AC1 -
AC2: 'Reply on AC1', Vincent Vionnet, 07 Aug 2025
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Dear Dr. Juan A. Añel,
Thank you very much for your detailed comments regarding our manuscript.The SVS2 code within the ECCC Surface Prediction System is now available in a permanent repository: https://doi.org/10.5281/zenodo.16740463 (Vionnet et al., 2025b) This code has been used for the distributed simulations presented in our manuscript.
The scripts and data used to generate all the figures of the manuscript are also available on Zenodo: https://doi.org/10.5281/zenodo.16760831 (Vionnet et al., 2025c). In particular, this repository contains the observations used to evaluate the distributed simulations: (i) the snow pits data and (ii) the GMASI snow cover data. Both observation datasets are distributed in a NetCDF format. The configurations files for the point-scale and distributed simulations are also included in this repository.
The modified 'Code and Data Availability' in any future version of the manuscript will read as:
The SVS 2.0 code used for the point scale applications at Snow Crested Butte is available in a permanent repository: https://doi.org/10.5281/zenodo.14859640 (Vionnet et al., 2025a). The SVS 2.0 code used for the distributed simulations presented in this paper is available from https://doi.org/10.5281/zenodo.16740463 (Vionnet et al., 2025b). Scripts and data to produce the figures in this paper as well as SVS2 configurations files are available from https://doi.org/10.5281/zenodo.16760831 (Vionnet et al., 2025c). This repository also contains the observations used to evaluate the distributed snowpack simulations (snow pit data and GMASI snow cover data).
The other freely-available datasets used in this work are:
ERA5-Land data: https://doi.org/10.24381/cds.e2161bac
ERA5/Crocus dataset: https://doi.org/10.5281/zenodo.10943718
Global map of snow darkening coefficient for the snowpack model Crocus (Gaillard et al., 2024): https://doi.org/10.5281/zenodo.14194990
Snow Crested Butte dataset: https://doi.org/10.5281/zenodo.6618553
We hope these modifications make our manuscript compliant with the policy of the journal and guarantee the replicability of our results.
Thank you very much for your time and consideration.
Best regards,
Vincent Vionnet, on behalf of all the authors.References used in this answer:
Gaillard, M., Vionnet, V., Lafaysse, M., Dumont, M., and Ginoux, P.: Improved snow darkening coefficient for large-scale albedo modelling with Crocus [Dataset], Zenodo, https://doi.org/10.5281/zenodo.14194990, 2024.
Vionnet, V., Leroux, N., Fortin, V., Abrahamowicz, M., Woolley, G., Mazzotti, G., Gaillard, M., Lafaysse, M., Royer, A., Domine, F., Gauthier, N., Rutter, N., Derksen, C., & Belair, S. (2025a). Code of the land surface scheme Soil Vegetation and Snow version 2 integrated in the MESH platform (v1.0.0). Zenodo. https://doi.org/10.5281/zenodo.14859640
Vionnet, V., Leroux, N., Fortin, V., Abrahamowicz, M., Woolley, G., Mazzotti, G., Gaillard, M., Lafaysse, M., Royer, A., Domine, F., Gauthier, N., Rutter, N., Derksen, C., & Belair, S. (2025b). Code of the land surface scheme Soil Vegetation and Snow version 2 integrated in the ECCC Surface Prediction System. Zenodo. https://doi.org/10.5281/zenodo.16740463
Vionnet, V., Leroux, N., Royer, A., Domine, F., Fortin, V., Abramowicz, M., Woolley, G., Mazzotti, G., Gaillard, M., Lafaysse, M., Gauthier, N., Rutter, N., Derksen, C., & Belair, S. (2025c). Scripts and data to produce figures for the SVS2 paper submitted to GMD (Version v1) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.16760831
Citation: https://doi.org/10.5194/egusphere-2025-3396-AC2 -
CEC2: 'Reply on AC2', Juan Antonio Añel, 07 Aug 2025
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Dear authors,
Many thanks for your point-by-point reply. As a minor issue, it would be good if you could provide the exact ERA5 data used in your work in a repository, instead of simply linking the ERA5 webpage, which is not a reliable permanent repository and makes harder for readers to know exactly the files that you have used.
Juan A. Añel
Geosci. Model Dev. Executive Editor
Citation: https://doi.org/10.5194/egusphere-2025-3396-CEC2 -
AC3: 'Reply on CEC2', Vincent Vionnet, 08 Aug 2025
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Dear Dr. Juan A. Añel,
Thank you very much for your quick reply.Information about the ERA5 forcing data have been added to the permanent repository https://doi.org/10.5281/zenodo.16782503 (see the folder distributed_simulations/forcing). Scripts to download the ERA5 data from their original archives are provided as well as an example of ERA5-forcing file for SVS2 within the ECCC Surface Prediction System.
The modified 'Code and Data Availability' in any future version of the manuscript will read as:
The SVS 2.0 code used for the point scale applications at Snow Crested Butte is available in a permanent repository: https://doi.org/10.5281/zenodo.14859640 (Vionnet et al., 2025a). The SVS 2.0 code used for the distributed simulations presented in this paper is available from https://doi.org/10.5281/zenodo.16740463 (Vionnet et al., 2025b). Scripts and data to produce the figures in this paper as well as SVS2 configurations files are available from https://doi.org/10.5281/zenodo.16760831 (Vionnet et al., 2025c). This repository also contains the observations used to evaluate the distributed snowpack simulations (snow pit data and GMASI snow cover data). ERA5 atmospheric forcing have been obtained from https://doi.org/10.24381/cds.adbb2d47 and https://doi.org/10.24381/cds.143582cf as detailed in Vionnet et al. (2025c).
The other freely-available datasets used in this work are:
ERA5-Land data: https://doi.org/10.24381/cds.e2161bac
ERA5/Crocus dataset: https://doi.org/10.5281/zenodo.10943718
Global map of snow darkening coefficient for the snowpack model Crocus (Gaillard et al., 2024): https://doi.org/10.5281/zenodo.14194990
Snow Crested Butte dataset: https://doi.org/10.5281/zenodo.6618553
We hope these modifications make our manuscript compliant with the policy of the journal and guarantee the replicability of our results.
Thank you very much for your time and consideration.
Best regards,
Vincent Vionnet, on behalf of all the authors.References used in this answer:
Vionnet, V., Leroux, N., Fortin, V., Abrahamowicz, M., Woolley, G., Mazzotti, G., Gaillard, M., Lafaysse, M., Royer, A., Domine, F., Gauthier, N., Rutter, N., Derksen, C., & Belair, S. (2025a). Code of the land surface scheme Soil Vegetation and Snow version 2 integrated in the MESH platform (v1.0.0). Zenodo. https://doi.org/10.5281/zenodo.14859640
Vionnet, V., Leroux, N., Fortin, V., Abrahamowicz, M., Woolley, G., Mazzotti, G., Gaillard, M., Lafaysse, M., Royer, A., Domine, F., Gauthier, N., Rutter, N., Derksen, C., & Belair, S. (2025b). Code of the land surface scheme Soil Vegetation and Snow version 2 integrated in the ECCC Surface Prediction System. Zenodo. https://doi.org/10.5281/zenodo.16740463
Vionnet, V., Leroux, N., Royer, A., Domine, F., Fortin, V., Abramowicz, M., Woolley, G., Mazzotti, G., Gaillard, M., Lafaysse, M., Gauthier, N., Rutter, N., Derksen, C., & Belair, S. (2025c). Scripts and data to produce figures for the SVS2 paper submitted to GMD (Version v2) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.16782503
Citation: https://doi.org/10.5194/egusphere-2025-3396-AC3
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AC3: 'Reply on CEC2', Vincent Vionnet, 08 Aug 2025
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CEC2: 'Reply on AC2', Juan Antonio Añel, 07 Aug 2025
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AC2: 'Reply on AC1', Vincent Vionnet, 07 Aug 2025
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AC1: 'Reply on CEC1', Vincent Vionnet, 29 Jul 2025
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RC1: 'Comment on egusphere-2025-3396', Anonymous Referee #1, 19 Aug 2025
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The authors provide a comprehensive description of SVS2, including significant developments such as a revised snow albedo scheme, novel physical parameterizations for Arctic snowpack properties, and a new forest canopy module. They then demonstrate its capability to simulate snowpack properties, including microstructure, across extensive geographical regions. In general, this manuscript is well-written and suitable for publication in GMD. However, my major concern is that the authors have not clearly explained the impacts of these improvements on enhancing model performance.
Special comments:
- Line 535: Why did the authors apply normalization of total depth to each pair of simulated and observed profiles?
- Line 467 states that a dew point temperature threshold of 0 °C was used to separate total precipitation into liquid or solid precipitation in point-scale simulations. Line 510 mentions that precipitation phase in distributed simulations was determined based on hydrometeor temperature derived from downscaled air temperature and humidity. What is the difference between these two methods, and why were different methods applied in this study?
- In section 4.1 "Point-scale evaluation at Snow Crested Butte", the authors present an evaluation of the model in point-scale mode at Snow Crested Butte. They conducted simulations at both the open site and the forest site, with comparisons to on-site measurements. However, they mainly present the results simulated by SVS2/Crocus without explaining how the new forest canopy module enhanced simulation performance. A comparison between SVS1 and SVS2 is recommended to highlight the role of the new forest canopy module.
- The model did not accurately simulate the grain type of each layer, which is reasonable considering uncertainties in the observed snow type and in the model's snow grain diagnostics. My question is: if the simulation of grain type was unsatisfactory, was the inclusion of complex snow microstructure necessary? To what extent can the complex microstructure configuration improve model performance?
- Lines 591-593: Why can the Arctic configuration also improve simulations for sites below the treeline?
- The authors note that SVS2 has been previously applied in several studies, including Woolley et al. (2024), and they make comparisons with Woolley et al. (2024) throughout almost all parts of the manuscript. What, then, are the scientific advances of this study compared to Woolley et al. (2024)?
- The authors refined the snow albedo parametrization and indicated that they incorporated significant developments such as a revised snow albedo scheme. However, in the Results section, they did not demonstrate the impacts of such developments on model performance.
Citation: https://doi.org/10.5194/egusphere-2025-3396-RC1
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