Map Layer Info
| Peak Vegetation Growth | |
What this map layer shows: The peak level of vegetation growth in Alaska and the conterminous United States, for the years 1990 to 2005. |
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| Background Information | |
Sample Map
AVHRR imagery that covers the whole Earth is recorded every day, but the most commonly used AVHRR products are composite images that are created from AVHRR data every two weeks. Compositing two weeks of images means that data obscured by cloud cover on any particular day can be replaced by data recorded on a clear day during the same period. Biweekly AVHRR composites are the basis for Normalized Difference Vegetation Index (NDVI) calculations, which measure vegetation cover and plant growth. Because they indicate vegetation vigor, NDVI values are commonly called "greenness data." Generally, healthy vegetation is considered an indicator of favorable climatic and environmental conditions, while poor vegetation condition is indicative of droughts and diminished productivity. Greenness composites have been produced for the conterminous United States every two weeks since 1989, and for Alaska, during the growing season, since 1990. Greenness maps are used by government agencies and private industry for a wide variety of applications, including agricultural assessment, environmental monitoring and global climate change studies. The Peak Vegetation Growth map layers are 16 images that show the peak level of vegetation growth in Alaska and the conterminous United States for the years 1990 to 2005. They were produced by the National Atlas of the United States® with data provided by EROS. Peak greenness is calculated by examining all of the biweekly composites for a year, pixel-by-pixel, and recording the maximum NDVI value for each pixel. See the Greenness home page for further information on USGS greenness mapping. The National Atlas also includes Average Vegetation Growth map layers for the years 1990 to 2005. |
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| Map Maker Samples |
| Vegetation Growth - Peak: 1990 |
| Vegetation Growth - Peak: 1997 |
| Vegetation Growth - Peak: 2005 |
| Dynamic Maps |
| Vegetation Growth in the United States |
