Py6S and Sentinel 2 parameters (geometry - wavelength)

[lucia.m...@gmail.com]

Dear Robin,

I started using Py6S, it's a very useful tool!

I saw there are a lot of sensor's parameters stored in the geometry and wavelength classes.

Do you plan to update the code and to include Sentinel 2 parameters?

Thank you in advance

Maria Lucia

[Robin Wilson]

Hi,

Yes, I am intending to add the Sentinel 2 wavelengths, I just haven't had time to do so yet. If you're able to direct me to data on the Sentinel 2 spectral response functions (it needs to be detailed data in something like a CSV file or Excel spreadsheet) then I can have a look at trying to get it into the right format for Py6S.

As for geometries: that's a bit more difficult, and I haven't really got into that yet. 6S has the geometry stuff for Landsat TM/ETM built in, but I need to look at how they do it and see if I can work out how to do a similar thing for Sentinel 2 (and Landsat 8, and RapidEye etc). That's more of a long-term plan, to be honest.

Cheers,

Robin

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[lucia.m...@gmail.com]

Dear Robin,

thank you for your reply.

You can dowload the Excel spreadsheet of the spectral responces from this link.

https://earth.esa.int/documents/247904/685211/Sentinel-2A+MSI+Spectral+Responses

I suppose I can use the info reported in the kml file to define Sentinel 2 acquisition geometry.

Thank you in advance

MLucia

[Marcin Kawka]

For those who are interested - I modified the 6S source code and included Landsat 8 and Sentinel-2 spectral response functions from ESA/NASA web sites.

You just need to select proper band in your 6S configuration file (usually row 8):

- Landsat 8 bands 1 - 8 are encoded as 200 - 208

- Sentinel2 bands 1 to 12 are 209 - 220 and band 8a is 221

As for geometry conditions I was a bit unsure whether I should change anything in the source code. As far as I understand the code sensors 7 (Landsat TM) and 6 (HRV) use the same function. Thus I assume, that Landsat 8 and Sentinel-2 should also use it.

I'm not an expert on atmospheric correction, so if you have any suggestions/comments, do not hesitate to email me. I haven't tested the code very much, you use it on your own risk. I would appreciate if you comment on your results.

Regards,

Marcin.

[Robin Wilson]

Hi,

Thanks Marcin for sending this around. I just wanted to warn people using Py6S that this updated version of 6S will not currently work with Py6S - partly because it is based on 6SV2.1 (which Py6S doesn't yet support) and partly because Py6S doesn't understand the new bands above 200.

However, Py6S does currently support Landsat 8 OLI (use PredefinedWavelengths.LANDSAT_OLI_B1 and so on), and it will support Sentinel-2 very soon (it is near the top of my to do list for when I get back from the conference I'm at currently).

Cheers,

Robin

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<6SV2.1_OLI_SENTINEL2.tar.gz>