Seasonal Variations in the Vegetation for 1986

In the images, the white areas represent the ocean and large lakes. The bright colors (red, light blue, etc) represent a high Normalized Digitized Vegetation Index (NDVI) values, while the dark colors represent low NDVI values. Seasonal variations of the NDVI values are noticeable in the animations.

Northeast US
Japan and Korea

The NDVI is defined by

Where b2 and b1 refer to the reflected radiation at channel 2 (IR radiation) and channel 1 (visible red light). High values of NDVI, representing high reflectance in the IR band (and low reflectance in the red), means the foliage is healthy and abundant with green vegetation, where as low values could reflect on the lack of green leaves, higher pigmentation, or unhealthy foliage. Most plants, trees, vegetation, and agricultural land have characteristic reflection spectrums.

NDVI values can be used for analyzing seasonal variations in the foliage, monitoring agricultural activities, or studying the effects of deforestation and urban development. Differences in NDVI values can be attributed to locations like mountainous areas, desert areas, and rain forests.

The data was part of the NOAA/NASA Pathfinder Advance Very High-Resolution Radiometer (AVHRR) Land program. The AVHRR is a broad band sensor operating with 5 bands: 1 in the red, 1 in the near IR, and three bands in the far IR as listed in the table. The period covered is from 1981 to 1994 using the meteorological satellites NOAA-7, 9, and 11. The satellites are sun synchronous, near polar orbits (inclinations of 98.8 degrees) with an altitude of 833 km and orbital periods of 102 minutes. The sensor provides global area coverage with resolutions of 4 km resolution at nadir with a swath of 2399 km wide. Data was recorded during the afternoon hours of LMT.

Launch Date
June 23, 1981
December 12, 1984
September24, 1988
Afternoon Nodal Crossing Times
14:30 LMT
14:20 LMT
13:40 LMT
Service dates
08/24/81 - 06/07/86
02/25/85 - 05/11/94
11/08/88 - 09/13/94

The data was obtained from the
Goddard Distributed Active Archive Center

Visualizations by Dr. Jeff Mirick