UN SPIDER: Data application of the month: Vegetation indices

8 February 2015

What are vegetation indices used for?

Vegetation indices derived from Earth observation satellites are important for a wide range of applications such as vegetation monitoring, drought studies, agricultural activities, climate and hydrologic modeling. Vegetation monitoring plays an important role in drought early warning systems, which help to anticipate the risk of food crises at local and global scale.

How are vegetation indices measured from space?

Optical satellite sensors measure the solar radiation reflected from targets on the ground. Multispectral optical sensors are multichannel detectors with a few spectral bands. Each channel is sensitive to radiation within a narrow wavelength band such as the blue, green, red, near infrared, or short wave infrared band. The reflection of radiation by vegetation shows low values in the blue and red band, slightly higher values in the green band, very high values in the near infrared band, and low to high values in the shortwave infrared bands (depending on the wavelength). Very characteristic for the vegetation spectrum is the steep increase of reflectance from red to near infrared, the so called “red edge”. Multispectral sensors do not “see” the whole electromagnetic spectrum but their bands cover parts of the spectrum that are characteristic for different land cover types.

You can find more information from UN SPIDER in the Updates January 2015

Click here to read or download the Updates on the Knowledge Portal

You can also go straight to your topic of interest:

UN-SPIDER at a glance

Data application of the month