Source: This image was generated
using Geospatial Indicators Model from
ISCIENCES.
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Drought conditions have persisted
throughout northern Africa, Central, South and East Asia
for three years, with certain regions receiving less than
50 percent of normal precipitation. The impact of the drought
in Afghanistan has received much public attention recently
and throughout Central Asia, agricultural production has
been down every year - in some cases, requiring response
from food emergency agencies. Vegetation observed from satellites
exhibits significant effects in these regions, including
severe decline in net primary productivity.
The image above dramatically
reveals the extent of anomalous precipitation patterns.
Precipitation departures from normal over the period
January 1999 to December 2001 are displayed in color
tones ranging from green (above average rainfall) to
red (below average rainfall). Note the extent of the
red band starting near the tropic of Capricorn in western
Africa and continuing to the 45th parallel in northeastern
China. Central Asian states are particularly hard hit,
with precipitation less than 50 percent of normal over
a three-year period. Preliminary analysis by climatologists
at the International
Research Institute for Climate Prediction (IRI),
Columbia University, suggests that the drought is related
to large-scale variations in the climate across the Indian
and Pacific Oceans, including the recent "La Niņa" in
the eastern Pacific.*
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ISCIENCES created this image
by processing monthly precipitation data from the Global
Precipitation Climatology Center (GPCC) in Kassel, Germany. GPCC
reports monthly precipitation data in millimeters at one-degree intervals
across the globe, dating back to 1986. The monthly global images
are constructed using data from over 6000 weather stations that are
reporting regularly to the World Meteorological Organization. ISCIENCES
processed the GPCC data to compute precipitation anomalies by comparing
the total precipitation reported at each one-degree cell over the
three-year period to the average precipitation. Total precipitation
can be calculated for any time period of interest (month, quarter,
year, etc.; in this case, three years) by adding the reported monthly
precipitation over the period of interest and dividing that value
by the average rainfall experienced at that pixel over all three
year periods reported since 1986.
*The Drought and Humanitarian Crisis
in Central and Southwest Asia: A Climate Perspective, International
Research Institute for Climate Prediction, Columbia University, 2001.
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