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Worksheet: Drought in the MediterraneanSheet 2: Drought driving factors |
In the text “Drought in the Mediterranean” you have read about the NVDI. Two Explanations of NVDI are:a) Normalized Difference Vegetation Index (NDVI) imagery is calculated from the red and near infra-red reflectance observed by the AVHRR (Advanced Very High Resolution Radiometer) sensor on NOAA meteorological satellites. The NDVI image provides an indication of the vigour and density of vegetation at the surface. Images of NDVI are sometimes referred to as "greenness maps" since they represent the vegetative vigour of plants. The time series of NDVI data (from 1982 to the present) allows analysis of changes in vegetation vigour and density in response to bio-physical conditions (including plant type, weather and soil). The primary use of these images is to compare the current state of vegetation with previous time periods, for example the same time in an average year or a reference year (a particularly good or bad year) to detect anomalous conditions.
Calculating the ratio of the visible and near-infrared light reflected back up to the sensor yields a number from minus one (-1) to plus one (+1). The result of this calculation is called the Normalized Difference Vegetation Index, or NDVI. An NDVI value of zero means no green vegetation and close to +1 (0.8 - 0.9) indicates the highest possible density of green leaves.
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Please click for a higher resolution into the picture! (330 K)
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Exercise 4:Is this typical for Mediterranean climate?
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Exercise 6:Have a look into your atlas. Exercise 7:You have learnt about the water use in Spain and Norway and the relations between water resources and water use in those two countries. First have a guess how the situation is there, then look at the website Transform the data for water use into a circle diagram and compare the water use and the water resources of your country to the situation of Spain.
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About this page:- Author: S. Schnell - University of Nürnberg - Germany
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