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The images used in this exercise are twelve SPOT-NDVI images for the year 2000 in TIFF format. They are numbered 1 to 12: 1 corresponds to January, 2 to February and so on. For each image, you will create subsets for each biogeographical area. You will then calculate the mean NDVI value of each area for each month and create graphs to compare them over time.  
 
Part 1: Creating the subsets
 
In LEOWorks the origin of the image is in the top left corner (1, 1) and the end of the image in the bottom right corner (1568, 1703). The ‘X’ represents the latitude (or row) and the ‘Y’ represents the longitude (or column).

The areas we are going to analyse are representative of different types of vegetation and ecosystems, the so-called biogeographical zones.

You can find information on biogeographical zones in the background articles (see right).

The approximate coordinates of our areas of interest are the following:
 
 

Zones Maximum latitude Minimum latitude Maximum longitude Minimum longitude Rainforest 10° S 0° S 70° W 60° W Tropical dry forest 20° S 18° S 62° W 59° W Temperate forest (broadleaf) 41° S 40° S 73°38’ W 72°51’ W Savannah 5° N 7° N 70° W 68° W Deserts 30° S 20° S 70° W 65° W Dry steppe 48° S 45° S 70° W 68° W Ice sheets 52° S 47° S 74° W 73° W

 
 

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