the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
The Pléiades Glacier Observatory: high resolution digital elevation models and ortho-imagery to monitor glacier change
Abstract. Spaceborne digital elevation models (DEMs) of glaciers are essential to describe their health, and their contribution to river runoff and to sea level rise. Publicly available DEMs derived from submeter satellite stereo-imagery were, up to now, mainly available in the polar regions and High Mountain Asia. Here, we present the Pléiades Glacier Observatory (PGO), a scientific programme acquiring Pléiades stereo pairs for 140 sites from Earth’s glacierized areas. The PGO product consists of DEMs at 2 m and 20 m ground sampling distance together with 0.5 m (panchromatic) and 2 m (multispectral) ortho-images. The DEMs are freely available to all registered users whereas ortho-images are available after signing a licence. PGO commenced in July 2016 in the North Hemisphere and February 2017 in the South Hemisphere. Each site is revisited every five years (cloud permitting), close to the end of the melt season, to measure glacier elevation change with an average uncertainty of 0.49 m (95 % confidence level, for a glacierized area of 1 km2), i.e. 0.1 m a-1. PGO samples over 20,000 km2 of glacierized terrain which represents about 3 % of the Earth’s glaciers area. This small sample, however, provides a first order estimate of the global glacier mass change and its decadal evolution.
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Status: closed
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RC1: 'Comment on egusphere-2024-250', Anonymous Referee #1, 23 May 2024
In their TCD manuscript “The Pléiades Glacier Observatory: high-resolution digital elevation models and ortho-imagery to monitor glacier change” Berthier et al. introduce a contentiously growing topographic dataset of 140 glacierized areas around the world termed the Pléiades Glacier Observatory (PGO). For each region, one Pleiades stereo acquisition is acquired every 5 years to monitor the glacier's state and health at the globally distributed benchmark sites. The data will be processed to Digital Elevation Models (DEMs) and orthoimagery and will be made publicly available.
This is a very valuable dataset for the glaciological society to document ongoing glacier changes around the world and I want to thank the authors for making this happen. Overall the manuscript is well structured and written and I suggest publication after correcting some minor points which I list in the following.
Specific comments:
L19-20: short general information about the Pleiades satellite mission should be included in the abstract.
L27-28: is this shown in the manuscript? (Well, yes in section 4) Can you quantify it here?
L39: what about InSAR and altimetry? Maybe include a brief intro in this paragraph or at least that these methods also exist?
L73: here also Holzer et al., 2015 could be cited
L77-81: this is important and I and probably the entire glaciological community are very thankful for your efforts.
L185: What are the specifications of the Copernicus GLO-30 DEM (e.g. resolution (from the naming I guess 30 m...), accuracy etc.)?
L239: off-glacier I presume, but maybe write it explicitly.
L246-L248: I agree with this point and it also raises the question why the authors did not coregister to a more precise dataset such as ICESat/ICESat-2 altimetry? Is there a particular reason? I could imagine track spacing and surface slope are an issue?
L396: what is GTN-G again?
Additional References:
Holzer, N., Vijay, S., Yao, T., Xu, B., Buchroithner, M., and Bolch, T.: Four decades of glacier variations at Muztagh Ata (eastern Pamir): a multi-sensor study including Hexagon KH-9 and Pléiades data, The Cryosphere, 9, 2071–2088, https://doi.org/10.5194/tc-9-2071-2015, 2015.
Citation: https://doi.org/10.5194/egusphere-2024-250-RC1 -
AC2: 'Reply on RC1', Etienne Berthier, 07 Jun 2024
We thank David Shean for providing a thorough and constructive review of our manuscript. Please find attached our preliminary answers to his main comments. The response to the specific/minor comments will be detailed in our final response letter if the editor considers that our manuscript is appropriate for The Cryosphere.
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AC2: 'Reply on RC1', Etienne Berthier, 07 Jun 2024
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RC2: 'Comment on egusphere-2024-250', David Shean, 26 May 2024
See pdf for review.
The formal manuscript rating questions emphasize "scientific understanding," which is challenging/ambiguous for this manuscript, as the focus is on methods and new data products, rather than new cryosphere science. The PGO data products will likely have significant impact for the science community moving forward, but this manuscript does not directly include any significant/high-impact science. Hopefully that makes sense - see detailed review for further comments on this topic.-
AC1: 'Reply on RC2', Etienne Berthier, 07 Jun 2024
We thank the anonymous reviewer for the positive review of our manuscript and kind comments. The response to their specific/minor comments will be detailed in our final response letter if the editor confirms that our manuscript is appropriate for The Cryosphere.
Citation: https://doi.org/10.5194/egusphere-2024-250-AC1
-
AC1: 'Reply on RC2', Etienne Berthier, 07 Jun 2024
Status: closed
-
RC1: 'Comment on egusphere-2024-250', Anonymous Referee #1, 23 May 2024
In their TCD manuscript “The Pléiades Glacier Observatory: high-resolution digital elevation models and ortho-imagery to monitor glacier change” Berthier et al. introduce a contentiously growing topographic dataset of 140 glacierized areas around the world termed the Pléiades Glacier Observatory (PGO). For each region, one Pleiades stereo acquisition is acquired every 5 years to monitor the glacier's state and health at the globally distributed benchmark sites. The data will be processed to Digital Elevation Models (DEMs) and orthoimagery and will be made publicly available.
This is a very valuable dataset for the glaciological society to document ongoing glacier changes around the world and I want to thank the authors for making this happen. Overall the manuscript is well structured and written and I suggest publication after correcting some minor points which I list in the following.
Specific comments:
L19-20: short general information about the Pleiades satellite mission should be included in the abstract.
L27-28: is this shown in the manuscript? (Well, yes in section 4) Can you quantify it here?
L39: what about InSAR and altimetry? Maybe include a brief intro in this paragraph or at least that these methods also exist?
L73: here also Holzer et al., 2015 could be cited
L77-81: this is important and I and probably the entire glaciological community are very thankful for your efforts.
L185: What are the specifications of the Copernicus GLO-30 DEM (e.g. resolution (from the naming I guess 30 m...), accuracy etc.)?
L239: off-glacier I presume, but maybe write it explicitly.
L246-L248: I agree with this point and it also raises the question why the authors did not coregister to a more precise dataset such as ICESat/ICESat-2 altimetry? Is there a particular reason? I could imagine track spacing and surface slope are an issue?
L396: what is GTN-G again?
Additional References:
Holzer, N., Vijay, S., Yao, T., Xu, B., Buchroithner, M., and Bolch, T.: Four decades of glacier variations at Muztagh Ata (eastern Pamir): a multi-sensor study including Hexagon KH-9 and Pléiades data, The Cryosphere, 9, 2071–2088, https://doi.org/10.5194/tc-9-2071-2015, 2015.
Citation: https://doi.org/10.5194/egusphere-2024-250-RC1 -
AC2: 'Reply on RC1', Etienne Berthier, 07 Jun 2024
We thank David Shean for providing a thorough and constructive review of our manuscript. Please find attached our preliminary answers to his main comments. The response to the specific/minor comments will be detailed in our final response letter if the editor considers that our manuscript is appropriate for The Cryosphere.
-
AC2: 'Reply on RC1', Etienne Berthier, 07 Jun 2024
-
RC2: 'Comment on egusphere-2024-250', David Shean, 26 May 2024
See pdf for review.
The formal manuscript rating questions emphasize "scientific understanding," which is challenging/ambiguous for this manuscript, as the focus is on methods and new data products, rather than new cryosphere science. The PGO data products will likely have significant impact for the science community moving forward, but this manuscript does not directly include any significant/high-impact science. Hopefully that makes sense - see detailed review for further comments on this topic.-
AC1: 'Reply on RC2', Etienne Berthier, 07 Jun 2024
We thank the anonymous reviewer for the positive review of our manuscript and kind comments. The response to their specific/minor comments will be detailed in our final response letter if the editor confirms that our manuscript is appropriate for The Cryosphere.
Citation: https://doi.org/10.5194/egusphere-2024-250-AC1
-
AC1: 'Reply on RC2', Etienne Berthier, 07 Jun 2024
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