NDMI Annual Range

Land Usev0

Responsible:Niccolò Calandri

NDMI Annual Range

Overview

The NDMI Annual Range measures the pixel-wise difference between the maximum and minimum NDMI values recorded over a one-year period. This indicator captures the seasonal variability of vegetation water content, providing information on water stress and canopy moisture resilience.

Formula:

NDMI_range = NDMI_max − NDMI_min (pixel-wise, annual basis)

NDMI following Gao (1996):

NDMI = (NIR − SWIR1) / (NIR + SWIR1)

where NIR = B8 (842 nm) and SWIR1 = B11 (1610 nm) from Sentinel-2.

Interpretation of values:

High range values (> 0.4) → strong seasonal leaf moisture variation; rainfed agriculture, deciduous forests
Moderate range values (0.2–0.4) → moderate moisture variation; mixed vegetation
Low range values (< 0.2) → stable vegetation moisture; irrigated areas, evergreen forests

The indicator is useful for:

Monitoring seasonal water stress in vegetation
Identifying areas with drought vulnerability
Distinguishing between irrigated and rainfed agriculture
Assessing ecosystem resilience to water variations

Calculation Methodology

Dataset: Sentinel-2 Surface Reflectance Harmonized (ESA/Copernicus), bands B8 (NIR, 842 nm, 10 m) and B11 (SWIR1, 1610 nm, 20 m). Final resolution: 20 m.

Data acquisition — all Sentinel-2 images over the calendar year
Cloud masking — via SCL
NDMI calculation per image — NDMI = (B8 − B11) / (B8 + B11)
Pixel-wise max and min extraction
Range calculation — NDMI_range = NDMI_max − NDMI_min
Reprojection

Data Sources

Code	Name	Provider	Resolution	Availability
`WRD_S2XXX_99`	ESA Sentinel-2 L2A	ESA/Copernicus	10–20 m	2017-03-28 — present

Technical Notes

Final resolution is 20 m, determined by B11 (SWIR1)
Sensitive to cloud-free scene availability and atmospheric moisture
In bare soil areas, NDMI may reflect soil moisture rather than vegetation moisture
Dimensionless index, theoretical values between 0 and 2

References

Gao, B.-C. (1996). Remote Sensing of Environment, 58(3), pp. 257–266.
Wilson, E.H., Sader, S.A. (2002). Remote Sensing of Environment, 80(3), pp. 385–396.
Ceccato, P. et al. (2001). Remote Sensing of Environment, 77(1), pp. 22–33.

Data Sources & References

Sources

WRD_S2XXX_99

Methodology

Il range dell'NDMI viene calcolato a partire dalle immagini Sentinel-2 Surface Reflectance Harmonized, utilizzando le bande B8 (NIR, 842 nm, 10 m) e B11 (SWIR1, 1610 nm, 20 m). La risoluzione finale è di 20 metri. Per ciascuna immagine disponibile nell'anno, viene calcolato l'NDMI = (B8 − B11) / (B8 + B11) dopo mascheramento cloud via SCL. Per ciascun pixel, vengono estratti i valori massimo e minimo dell'NDMI sull'anno, e il range è calcolato come differenza (NDMI_range = NDMI_max − NDMI_min).

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NDMI Annual Range

Land Usev0

Responsible:Niccolò Calandri