Major climate indicators of ongoing drought in Sudan

Abstract

Summary There has been a rigorous debate during the 2000s about the recovery of the African Sahel from the long-lasting drought. To examine the situation in Sudan, this paper develops the standardized anomaly indices (SAIs) of mean annual temperature and annual rainfall, and accordingly, establishes the Pedj drought index (PDI) since the 1940s to 2008 for 14 stations spread over the country. There has been a drastic increase in temperatures (maximum, minimum, and mean) over the whole country in line with a significant decline of rainfall over the northern half of the country. Evidence of a correlation between temperature and rainfall anomalies has been reported, emphasizing the concurrence of dry and hot periods. These results suggest less effective rainfall. Contrary to the postulation of recovery from the long-lasting drought in the African Sahel, the results for Sudan indicate intensifying drought evidenced by significant rising trends in PDI. The 2000s depict a widespread and prolonged drought (mild to severe), except for the extreme southern and south-western parts of the country which displayed excess of humidity. The frequency of occurrence of drought classes during 1975–2008 ranged from 44.1% to 70.6% compared to a frequency extending from 8.8% to 40.0% for 1941–1974. The PDI succeeded to represent satisfactorily drought episodes captured by other drought indices recommended worldwide. El Nino-Southern Oscillation (ENSO) index has a significant footprint on the PDI, strongly affecting the country south of latitude 15°N.