Table of Contents
International Journal of Atmospheric Sciences
Volume 2014 (2014), Article ID 759067, 11 pages
Research Article

An Advanced Review of the Relationships between Sahel Precipitation and Climate Indices: A Wavelet Approach

Beltsville Center for Climate System Observation, Atmospheric Science Program, Howard University, Washington, DC 20059, USA

Received 15 January 2014; Revised 25 March 2014; Accepted 26 March 2014; Published 28 April 2014

Academic Editor: Helena A. Flocas

Copyright © 2014 Churchill Okonkwo. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The interannual and decadal to multidecadal variability of precipitation in western Sahel region was examined using wavelet transform and coherency analysis. The aim was to identify the major climate index that has a robust relationship with Sahel precipitation (drought). The results show that ENSO, North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation (AMO), and Indian Ocean Dipole (IOD) all have some relationship with precipitation at different time scales which is in agreement with recent studies. There is an antiphase relationship between Sahel precipitation and ENSO at the 3-4-year band localized around 1982/83 El Niño episode. This indicates a cause and effect relationship between the droughts of 1983 and 1982/83 El Niño. In addition, wavelet transform coherence analysis also revealed a relatively antiphase relationship between AMO and precipitation signifying cause and effect. The wavelet analyses indicate that IOD control on rainfall variability in Sahel is limited to the east (15°E–35°E). Advancing this understanding of variability in rainfall and climate forcing could improve the accuracy of rainfall forecast.