Hi Niklas,
Sorry, but I don't think there is much that can be done about that, the MOD09 products are not recommended for water pixels.
The "anomalies" that you've identified, e.g. negative reflectance values,
are known issues in MODIS along with many other Surface Reflectance products such as Landsat surface reflectance.
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. The surface reflectance QA bands and product user guides should
be consulted.
Please let me know if you have any questions.
Thanks,
Brett
Sorry, but I don't think there is much that can be done about that, the MOD09 products are not recommended for water pixels.
The "anomalies" that you've identified, e.g. negative reflectance values,
are known issues in MODIS along with many other Surface Reflectance products such as Landsat surface reflectance.
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. The surface reflectance QA bands and product user guides should
be consulted.
Please let me know if you have any questions.
Thanks,
Brett
Statistics: Posted by LP DAAC - lien — Fri Feb 16, 2024 10:37 am America/New_York