Lesson 1
Meteorological Satellite Orbits
Lesson 2
Review of Radiative Transfer
Lesson 3
Visible Image Interpretation
Lesson 4
Infrared Image Interpretation
Lesson 5
Multispectral Image Interpretation
Lesson 6
Fires & Aerosols
Lesson 7
Lesson 8
Lesson 9
Fog and Stratus
Lesson 10
Lesson 11
Lesson 12
Lesson 13
Global Circulation
Lesson 14
Synoptic Scale
Lesson 15
Global Circulation
Lesson 16
Satellite Oceanography
Lesson 17

Vegetation Index - NDVI

A common method of monitoring surface vegetation is through the Normalized Difference Vegetation Index:


This has long been used to monitor the vegetation, and changes in vegetation of the entire earth. NDVI for vegetation generally range from 0.3 to 0.8, with the larger values representing 'greener' surfaces. Bare soils range from about 0.2 - 0.3.

Healthy vegetation reflects very well in the near infrared part of the spectrum. Green leaves have a reflectance of 20 percent or less in the 0.5 to 0.7 micron range (green to red) and about 60 percent in the 0.7 to 1.3 micron range (near infra-red). NDVI provides an estimate of vegetation health and a means of monitoring changes in vegetation over time. The the typical range of NDVI is between about -0.1 (NIR less than VIS for a not very green area) to 0.6 (for a very green area).

Here is an example of NDVI over Europe, derived by German Remote Sensing Data Center.

Non-desert vegetation 0.01 - 0.75
Lakes, rivers, and ocean negative values
Sparse desert vegetation 0-0.01
Clouds 0-0.075
Typical Values of NDVI

The NDVI is typically derived from observations from the Advanced Very High Resolution Radiometer (AVHRR), which makes observations a five wavelengths (early versions has only four observations). The AVHRR makes observations in the visible, near-infrared, and thermal infrared portions of the electromagnetic spectrum. This sensor is carried on NOAA's Polar Orbiting Environmental Satellites (POES), beginning with TIROS-N in 1978.


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