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African Vegetation: Comparing September 1984 and September 1994
For many years, scientists have believed that the southern expansion of the Sahara has been due to human activity. However, results from the AVHRR instrument and its measurements of vegetation suggest a different explanation: rainfall patterns. In drier years (1984 was one of the driest summers in recorded history in Northern Africa), the Sahara expands south, but in wetter years (such as 1994), vegetation moves back and there is no net expansion of the Sahara as had been previously suggested.

An animation of vegetation changes in North Africa from September 1984 to September 1994, from AVHRR data    An animation of vegetation changes in North Africa from September 1984 to September 1994, from AVHRR data
Duration: 7.0 seconds
Available formats:
  352x240 (29.97 fps) MPEG-1   1 MB
  320x242     JPEG         7 KB
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NDVI measures of African continent, September 1984    NDVI measures of African continent, September 1984

Available formats:
  1152 x 1152     TIFF 2 MB
  256 x 256         GIF       36 KB
  512 x 512         JPEG   206 KB


NDVI measures of African continent, September 1994    NDVI measures of African continent, September 1994

Available formats:
  1152 x 1152     TIFF 2 MB
  256 x 256         GIF       36 KB
  512 x 512         JPEG   210 KB
  160 x 80           PNG       19 KB


NDVI measures of north Africa, September 1984    NDVI measures of north Africa, September 1984

Available formats:
  640 x 486         TIFF (Without date) 581 KB
  80 x 40             PNG         4 KB
  160 x 80           PNG       17 KB
  320 x 243         JPEG     67 KB
  640 x 486         TIFF (With date) 582 KB


NDVI measures of north Africa, September 1994    NDVI measures of north Africa, September 1994

Available formats:
  640 x 486         TIFF (Without date) 585 KB
  320 x 243         JPEG     69 KB
  640 x 486         TIFF (With date) 586 KB

Animation Number:591
Completed:1999-01-01
Animator:Jesse Allen (Raytheon) (Lead)
Scientists:Compton Tucker (NASA/GSFC)
 Sharon Nicholson (Florida State University)
Platforms/Sensors/Data Sets:NOAA-11/AVHRR (1994/09)
 NOAA-12/AVHRR (1994/09)
 NOAA-7/AVHRR (1984/09)
 NOAA-8/AVHRR (1984/09)
Video:SVS1999-0008 *
Keywords:
DLESE >> Climatology
DLESE >> Physical geography
SVS >> Sahara
GCMD >> Location >> Africa
More Information on this topic available at:
stories/NDVI/africa_sept8494.html
 
 
Please give credit for this item to:
NASA/Goddard Space Flight Center
Scientific Visualization Studio


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