Kelp Talk

What part of this is kelp?

  • Quia by Quia

    This image looks different from most I've classified, possibly because it's newer/higher res imagery, are the dark areas around the green kelp also kelp?

    Posted

  • HMB6EQUJ5 by HMB6EQUJ5

    If I were classifying it, i would just go for the "green" don't recall if i've encountered that prior. perhaps there's others here who know for certain. Best wishes Quia!

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  • jebyrnes by jebyrnes scientist

    Wow! Neat bed! Indeed, go for the green. The surface slicks may also be kelp just below the surface - faint kelp. I'll ping the more landsat adept members of the team to give you a better answer.

    Posted

  • tombell by tombell scientist, translator

    I agree that most of the darker parts of the image are most likely kelp, just at a lower canopy density. The total area of bright green and dark area matches the shape of the La Jolla kelp forest fairly well, but the users are correct to be cautious.

    The reason that the areas appear dark is because most of the water in this image reflects a lot of sun glint. Kelp canopy reduces small capillary waves (small local wind generated waves) on the surface of the ocean and makes the water surface more flat. This reduces glint in those areas, and makes them appear relatively dark. So a lot of these dark areas are actually lower density kelp canopy.

    However, there are parts of the images that are dark and do not contain kelp canopy, most notably most northern stretch of coastline, north of the large bulge. If you look at the cartoonish kelp map I have linked below, you see that the kelp forest never extends to that region, as this is all most likely sandy bottom. It is just that this area is naturally sheltered and has less capillary waves to reflect sun glint.

    I would recommend outlining areas where you can see at least some greenish color.

    http://www.mexfish.com/enad/enad/ljkelpmp/ljkelpmp.jpg

    Posted

  • Quia by Quia

    Thank you for the in-depth answer!

    Followup question, images that have so much 'sun glint' are not common. Is this effect due to weather, sun angle at the time of the image, image resolution...?

    Posted