Abstract
The vegetation fraction over the Ethiopian highlands exhibits large seasonal and multi-annual variability in the period 1982 to 2014. Northern areas are more sensitive to rainfall due to the brevity of the wet season. Differences in the regional climate during periods of high and low vegetation are analyzed using composite fields of rainfall, wind, humidity, sea temperatures, salinity and currents; and correlations at six-month lead-time. The key climatic driver of vegetation is the zonal overturning atmospheric circulation linking subsidence over the east Indian Ocean and ascent within an expanded African monsoon. Certain aspects of this Walker Cell reflect Pacific ENSO interaction with the Indian Ocean Dipole. During cold phase ENSO an upwelling Rossby wave and cool sea temperatures in the west Indian Ocean promote vegetation growth in the Ethiopian highlands.
Key words: Vegetation, climate forcing, prediction, Ethiopia.
