Analysis of Low-Level Atmospheric Moisture Transport Associated with the West African Monsoon

• DOI: 10.1175/jcli-d-14-00746.1
• Publication Date: 2015-03-11T20:56:42Z
• Authors: M. Issa Lélé; Lance M. Leslie; Peter J. Lamb
• Keywords: Intertropical Convergence Zone; Wet season; Westerlies

Abstract The major objective of this study is to re-evaluate the ocean–land transport moisture for rainfall in West Africa using 1979–2008 NCEP–NCAR reanalysis data. vertically integrated atmospheric water vapor flux surface–850 hPa calculated account total low-level contribution over Africa. Analysis mean monthly fluxes shows a progressive penetration into from south and west. During spring (April–June), northward forms “moisture river” transporting current Gulf Guinea coast. In peak monsoon season (July–September), southerly weakens, but westerly enhanced extends 20°N owing strengthening African jet off west Mean seasonal values components across boundaries indicate that zonal component largest contributor Sahel, while meridional contributes most For wet years Sahel rainy active anomalies are displaced farther north compared long-term average. This includes latitude intertropical front (ITF), extent flux, zone strong convergence, with an flow. dry years, opposite patterns observed. Statistically significant positive correlations between Sudan–Sahel totals pronounced when lead by 1–4 pentads. However, although weak, they still statistically at lags 3 4 fluxes.