The relationship between the Guinea Highlands and the West African offshore rainfall maximum

H. L. Hamilton, G. S. Young, J. L. Evans, J. D. Fuentes, K. M. Núñez Ocasio

Research output: Contribution to journalArticle

Abstract

Satellite rainfall estimates reveal a consistent rainfall maximum off the West African coast during the monsoon season. An analysis of 16 years of rainfall in the monsoon season is conducted to explore the drivers of such copious amounts of rainfall. Composites of daily rainfall and midlevel meridional winds centered on the days with maximum rainfall show that the day with the heaviest rainfall follows the strongest midlevel northerlies but coincides with peak low-level moisture convergence. Rain type composites show that convective rain dominates the study region. The dominant contribution to the offshore rainfall maximum is convective development driven by the enhancement of upslope winds near the Guinea Highlands. The enhancement in the upslope flow is closely related to African easterly waves propagating off the continent that generate low-level cyclonic vorticity and convergence. Numerical simulations reproduce the observed rainfall maximum and indicate that it weakens if the African topography is reduced.

Original languageEnglish (US)
Pages (from-to)1158-1166
Number of pages9
JournalGeophysical Research Letters
Volume44
Issue number2
DOIs
StatePublished - Jan 28 2017

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All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

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