Hello. I'm Seongjun Lee, and I have a question about the negative values from HLS products.
When I extracted specific pixel values from HLS bands, some pixel values have negative values.
I wonder what mean these negative values and, if these values should be removed or not.
Thanks :)
Negative values from HLS products
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seongjunlee
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LP DAAC-EDL - lien
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Re: Negative values from HLS products
Hello,
Negative values are common anomalies in Surface Reflectance data.
These are generally caused by water. The
atmospheric correction and surface reflectance retrieval algorithms are not
ideal for water bodies due to the inherently low level of water leaving
radiances and consequently very low SNR. Quantitative remote sensing
retrievals of water column constituents requires different algorithms.
Similarly reflectance values greater than 1.0 can be encountered over
bright targets such as snow and playas. These are computational
artifacts. You may want to consult the surface reflectance QA bands and product user guide for verification and more information.
Please let us know if you have any questions.
Thanks,
Brett
Negative values are common anomalies in Surface Reflectance data.
These are generally caused by water. The
atmospheric correction and surface reflectance retrieval algorithms are not
ideal for water bodies due to the inherently low level of water leaving
radiances and consequently very low SNR. Quantitative remote sensing
retrievals of water column constituents requires different algorithms.
Similarly reflectance values greater than 1.0 can be encountered over
bright targets such as snow and playas. These are computational
artifacts. You may want to consult the surface reflectance QA bands and product user guide for verification and more information.
Please let us know if you have any questions.
Thanks,
Brett