Images
November 26, 2007 - MODIS Vegetation Measurements
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The colors on these maps show a measure of the "greenness" of Earth's landscapes. The values on these maps have no unit. Rather, they are index values in which higher values show lands covered by green, leafy vegetation and lower values show lands where there is little or no vegetation.
As can be seen through a prism, many different wavelengths make up the spectrum of sunlight. When sunlight shines on objects, certain wavelengths are absorbed and other wavelengths are reflected. The pigment in plant leaves -- chlorophyll -- strongly absorbs visible light for use in photosynthesis. The cell structure of the leaves, on the other hand, strongly reflects near-infrared light. The more leaves a plant has, the more these wavelengths of light are affected. Scientists exploit this knowledge of plants' interactions with light to map the density of green vegetation across Earth's landscapes by designing satellite sensors to measure the wavelengths of red and near-infrared light that is absorbed and reflected by plants all over the world.
Subtracting plants' reflectance of red light from near-infrared light and then dividing that difference by the addition of the red and near-infrared light reflected produces a resulting value that scientists call Normalized Difference Vegetation Index (NDVI). The NDVI maps shown here were made using data collected by the MODIS aboard NASA's Terra satellite. This image shows the Earth between August 1 and September 1, 2007.
Plants are sensitive to their environment and so they serve as a good indicator whenever there is change. Scientists routinely produce global NDVI maps to help them monitor and investigate shifts in plant growth patterns that occur in response to climate changes, environmental changes, and changes caused by humans. Farmers and resource managers also use NDVI maps to help them monitor the health of our forests and croplands. So these maps are useful both for scientific research as well as societal benefit.
Dark green areas show where there was a lot green leaf growth; light greens show where there was some green leaf growth; and tan areas show little or no growth. Black means "no data."
You can view a high resolution image here.
Image Facts
Satellite:
Terra
Date Acquired: August 1, 2007 to September 1, 2007
Resolutions:
Bands Used:
Image Credit:
Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC
The colors on these maps show a measure of the "greenness" of Earth's landscapes. The values on these maps have no unit. Rather, they are index values in which higher values show lands covered by green, leafy vegetation and lower values show lands where there is little or no vegetation.
As can be seen through a prism, many different wavelengths make up the spectrum of sunlight. When sunlight shines on objects, certain wavelengths are absorbed and other wavelengths are reflected. The pigment in plant leaves -- chlorophyll -- strongly absorbs visible light for use in photosynthesis. The cell structure of the leaves, on the other hand, strongly reflects near-infrared light. The more leaves a plant has, the more these wavelengths of light are affected. Scientists exploit this knowledge of plants' interactions with light to map the density of green vegetation across Earth's landscapes by designing satellite sensors to measure the wavelengths of red and near-infrared light that is absorbed and reflected by plants all over the world.
Subtracting plants' reflectance of red light from near-infrared light and then dividing that difference by the addition of the red and near-infrared light reflected produces a resulting value that scientists call Normalized Difference Vegetation Index (NDVI). The NDVI maps shown here were made using data collected by the MODIS aboard NASA's Terra satellite. This image shows the Earth between August 1 and September 1, 2007.
Plants are sensitive to their environment and so they serve as a good indicator whenever there is change. Scientists routinely produce global NDVI maps to help them monitor and investigate shifts in plant growth patterns that occur in response to climate changes, environmental changes, and changes caused by humans. Farmers and resource managers also use NDVI maps to help them monitor the health of our forests and croplands. So these maps are useful both for scientific research as well as societal benefit.
Dark green areas show where there was a lot green leaf growth; light greens show where there was some green leaf growth; and tan areas show little or no growth. Black means "no data."
You can view a high resolution image here.
Image Facts
Satellite:
Terra
Date Acquired: August 1, 2007 to September 1, 2007
Resolutions:
Bands Used:
Image Credit:
Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC
