Hi everyone,
I’ve encountered an issue with requesting ERA5 ancillary data.
Until August 2024, the procedure described in the GitHub README worked fine but has since stopped functioning. The following link is now inactive: "https://cds.climate.copernicus.eu/api-how-to".
I discovered that ECMWF data has migrated to a new portal, so I updated the CDS API key with the new required information (https://forum.ecmwf.int/t/step-by-step- ... -beta/3743).
However, after updating the credentials, I tried running POLYMER again (using two different accounts and credentials), but it still doesn’t seem to work.
The error message is:
"requests.exceptions.HTTPError: 403 Client Error: Forbidden for url: https://api.ecmwf.int/v1/retrieve/v1/pr ... gle-levels"
Does anyone know how to resolve this issue?
Thanks in advance!
Problems with ERA5 ancillary data
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nicola.ghirardi
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- Location: Milan
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JoelleG
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- company / institution: University of Milan
- Location: Italy
Re: Problems with ERA5 ancillary data
Hello everyone,
I've also encountered this issue attempting to use ERA5 ancillary data.
Currently, I'm using Polymer for atmospheric correction of Sentinel-3 images over a deep, oligotrophic lake. However, when using NASA ancillary data, I often obtain results with multiple negative values in the following wavelengths: (400,) 665, (673,) 681 and 709.
Being able to use ERA5 ancillary data to compare with the results from using the NASA ancillary data would be important.
Has anyone managed to resolve this issue? I’d really appreciate any insights.
Thank you!
I've also encountered this issue attempting to use ERA5 ancillary data.
Currently, I'm using Polymer for atmospheric correction of Sentinel-3 images over a deep, oligotrophic lake. However, when using NASA ancillary data, I often obtain results with multiple negative values in the following wavelengths: (400,) 665, (673,) 681 and 709.
Being able to use ERA5 ancillary data to compare with the results from using the NASA ancillary data would be important.
Has anyone managed to resolve this issue? I’d really appreciate any insights.
Thank you!
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fsteinmetz
- Site Admin
- Posts: 319
- Joined: Fri Sep 07, 2018 1:34 pm
- company / institution: Hygeos
- Location: Lille, France
- Contact:
Re: Problems with ERA5 ancillary data
Hello, and apologies for the late reply.
The access to the ERA5 dataset should be working with the latest Polymer master branch. A fix related to the new cdsapi has been implemented in Polymer in late 2024. Please make also sure that you are using an up-to-date version of the cdsapi library.
That being said, (slightly) negative water reflectance values can appear with Polymer, when the actual reflectace value is close to zero.
Especially at band 709 which is not corrected for water vapour absorption (the development of this correction is planned).
The use of alternate ancillary data may not prevent these negative values.
Kind regards,
François
The access to the ERA5 dataset should be working with the latest Polymer master branch. A fix related to the new cdsapi has been implemented in Polymer in late 2024. Please make also sure that you are using an up-to-date version of the cdsapi library.
That being said, (slightly) negative water reflectance values can appear with Polymer, when the actual reflectace value is close to zero.
Especially at band 709 which is not corrected for water vapour absorption (the development of this correction is planned).
The use of alternate ancillary data may not prevent these negative values.
Kind regards,
François