title	parent	grand_parent	layout	permalink	nav_exclude	scripts	examples
Normalized Difference Chlorophyll Index	Sentinel-2	Sentinel	script	/sentinel-2/ndci/	true	Visualization script.js EO Browser eob.js Raw Values raw.js	zoom lat lng datasetId fromTime toTime platform evalscript 11 40.03498 -119.55734 S2L1C 2021-09-13T00:00:00.000Z 2021-09-13T23:59:59.999Z CDSE EOB 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

General description of the script

For Sentinel-2, the index looks like this:

$$NDCI = \frac{B5-B4}{B5+B4}$$

NDCI is an index that aims to predict the chlorophyll content in turbid productive waters. It is calculated using the red spectral band B04 with the red edge spectral band B05.

Description of representative images

Visualization of the NDCI index September 2021 over Pyramid Lake Nevada.

References

• Normalized difference chlorophyll index: A novel model for remote estimation of chlorophyll-a concentration in turbid productive waters{:target="_blank"}
• A spectral space partition guided ensemble method for retrieving chlorophyll-a concentration in inland waters from Sentinel-2A satellite imagery{:target="_blank"}
• Comparison of satellite reflectance algorithms for estimating chlorophyll-a in a temperate reservoir using coincident hyperspectral aircraft imagery and dense coincident surface observations{:target="_blank"}