High summer heat in 2003, drought in 2005 and 2006: vegetation in France was put to test. From space, Vegetation instruments, on board Spot 4 and 5 satellites, enabled to monitor this evolution.
|2003 animation||2005 animation||2006 animation|
blue: vegetation more sturdy than a normal year
green: nominal circumstances
red - black : very dry circumstances
To qualify the vegetation state, scientists use the NDVI*, a vegetation resistance index, which uses information supplied by the instrument in the red and near infrared. These images present, every 10 days, the difference (or anomaly) of the NDVI in 2003 and 2005, by refering to the index mean of two "normal" years (2002 and 2004).
In 2003, Midi-Pyrénées, the center and the east of France were the more impacted by the drought and the high summer heat.
In 2005, the south, the center and the west of France were the first impacted before the drought reached the north. The south-west benefited from heavy rains at the end of August, which explains the greener coloring on the September 2005 images.
At last in 2006, a serious drought and high temperatures happened at the beginning of the summer, but August was rainy (particularly the second decade of August) which enabled to decrease the effect of this drought.
The calibration, the correction of atmospheric effects, the clouds detection by the use of the data acquired during one month, are realised by CNES.
* NDVI : Normalised Difference Vegetation Index