Detection of oil in Sentinel 2 images

Optical Toolbox
#1

Hello! We are searching for oil in the Caspian Sea. Tell me what methods or tools can be used to identify oil slicks on optical images?
Thank you in advance!

#2

Hello Daniyar

Sun Glint - normally the bane of optical satellites - can be useful in this application. I’m not sure if the overpass of S2A and S2B are suited to it for your AOI, though.

Cheers

Jan

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#3

Thanks for the answer Jan!
And where to find this tool? Is there a technique?

#4

Jan is right, but it is not simple.
Sun glint is the direct reflection of the sun on the sea surface which acts as a mirror. The intensity of the sunglint spot depends on the sea surface roughness, which depends on the windspeed, and can be modified if there is an oil layer. When there is oil, the sea is less rough, and the sea surface concentrates the light near the exact sunglint direction, resulting in higher reflectance close to the sun glint exact angle (that we do not observe much with Sentinel-2). But it results in a lower reflectance a little further from the sun glint.

That’s a little complex, and for this purpose, radar images such as Sentinel-1, are used more often (and you should ask S1tbx mailing list)

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#5

Hi @OHagolle Olivier,
Thanks for your input. And you’re right, of course: it’s not simple. But I didn’t want to put @DANIYAR off!

Cheers

Jan

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#6

Thanks for the answer!
Can you tell me the literature or tutorial in this area? What tool should I use for this work?
Thank you in advance!

#7

For a basic example, you might start from here :
http://www.cesbio.ups-tlse.fr/multitemp/?p=5392

The first reference, still used (!) on sunglint is Cox and Munk , 1954

It can be used to estimate the standard wind speed, but I do not know how oil modifies that.
Olivier

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#8

Could you use Sentinel 1? There are algorithms already available within SNAP.

#9

Thank you! But we already use this technique for radar images. We are currently working on similar tools for Sentinel 2, in order to confirm Sentinel’s data 1

#10

Dear Daniyar

We have extensive experience in the field you mention. In case you are still interested, you can reach me in this mail:
juan@orbitaleos.com

Regards