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Vegetation cover can be measured by satellites. The reflectance of chlorophyll is much higher in the near infrared than in the visible portion of the spectrum. The Landsat satellites and the NOAA weather satellites make measurements in both spectral regions. By combining these measurements, in what is called the Normalized Difference Vegetation Index (NDVI), the vegetation cover can be inferred. The image at the right shows the maximum NDVI in the Middle East in 1990. The greens of the color scale are designed to indicate vegetation cover. Apart from mountainous regions in the north and south, significant vegetation grows only in the Nile Valley, near the Jordan River Valley, along coasts, and at a few places irrigated by well water in the Arabian Peninsula. An obvious reason for the sparse vegetation is the meager rainfall, but there is another reason. Click Next Page to learn what it is. |
Maximum NDVI (%) in 1990. From the "Global View" CD-ROM set published by NOAA's National Geophysical Data Center, Boulder, Colorado.
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