Tropical Oceans Thermodynamic and Atmospheric Modulations over Southern Ethiopian Climate, Water Resource and Vegetation Variability
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Date
2007-08
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Addis Ababa University
Abstract
Singular value decomposition, correlation and composite analyses were used to investigate the
tropical oceans thermodynamic and atmospheric modulations over the southern Ethiopian climate,
water resource and vegetation variability. Significant association is found between them using the
50 years ocean and climate dataset from 1951 to 2000 and vegetation data that range from 1981 to
2000.Both climate and vegetation dataset are obtained from international centers. River discharge
flow and water level dataset are obtained from the Ethiopian Water Resource. The study reveals
the strong association between Tropical oceans thermodynamic and atmospheric circulation and
climate, hydrology and vegetation over Southern Ethiopia. The tropical oceans sea surface
temperature anomalies contribute 50% to the short rain season (SON) of rainfall over Ethiopia but
a very small contribution to the long rain season (MAM) of the rainfall variability over the area.
These tropical oceans also have contributions for the vegetation variability to 51.6% during the
SON and 44.8% during the MAM seasons and for the water level variability to a 53% and 58%
during the short and long rainfall seasons of the southern Ethiopia, respectively. The Tropical
oceans heat content contributions also revealed with its 85.6% during the September through
December season but with a very small contribution during the March through May season. The
wet minus dry composite patterns of sea surface temperature and atmospheric analyses explain
during the regional and global atmospheric dynamics together with the Tropical oceans modulation
cause the climate, hydrology and vegetation variability. The correlation explains that tropical
Indian Ocean is strongly correlated with the short rains of Ethiopia having a 99% confidence level
and r=0.640 correlation coefficient. A 90-99% confidence level association except the MAM
season is demonstrated by the Atlantic ocean and also the tropical pacific ocean is seen correlated
more strongly than the other tropical oceans, particularly the December through February SST
anomaly has a strong association with the short rains over Ethiopia
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Keywords
Southern Ethiopian Climate