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Copy file name to clipboardexpand all lines: sentinel-2/ndmi/README.md
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# TODO: Replace links with new (short) ones, add CDSE, make new figures?
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## Evaluate and visualize
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## General description of the script
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The NDMI is a normalized difference moisture index, that uses NIR and SWIR bands to display moisture.
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The SWIR band reflects changes in both the vegetation water content and the spongy mesophyll structure in vegetation canopies,
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while the NIR reflectance is affected by leaf internal structure and leaf dry matter content but not by water content.
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The combination of the NIR with the SWIR removes variations induced by leaf internal structure and leaf dry matter content, improving the accuracy in retrieving the vegetation water content.
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The amount of water available in the internal leaf structure largely controls the spectral reflectance in the SWIR interval of the electromagnetic spectrum.
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SWIR reflectance is therefore negatively related to leaf water content. In short, NDMI is used to monitor changes in water content of leaves, and was [proposed by Gao.](https://www.sciencedirect.com/science/article/abs/pii/S0034425796000673){:target="_blank"}
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NDWI is computed using the near infrared (NIR) and the short wave infrared (SWIR) reflectance’s:
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NDMI is computed using the near infrared (NIR) and the short wave infrared (SWIR) reflectances:
_Note: NDWI index is often used synonymously with the NDMI index, often using NIR-SWIR combination as one of the two options. Gao, referenced above, also called the index NDWI. NDMI seems to be consistently described using NIR-SWIR combination. As the indices with these two combinations work very differently, with NIR-SWIR highlighting differences in water content of leaves, and GREEN-NIR highlighting differences in water content of water bodies, we have decided to separate the indices on our repository as NDMI using NIR-SWIR, and NDWI using GREEN-NIR._
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{: .note}
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NDWI index is often used synonymously with the NDMI index, often using NIR-SWIR combination as one of the two options. Gao, referenced above, also called the index NDWI. NDMI seems to be consistently described using NIR-SWIR combination. As the indices with these two combinations work very differently, with NIR-SWIR highlighting differences in water content of leaves, and GREEN-NIR highlighting differences in water content of water bodies, we have decided to separate the indices on our repository as NDMI using NIR-SWIR, and NDWI using GREEN-NIR.
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