Extended Abstract (212K)17B.3
Intraseasonal variability over tropical Africa
Adrian J. Matthews, Univ. of East Anglia, Norwich, United Kingdom
Coherent patterns of intraseasonal variability in deep convection over tropical Africa are presented, based on an EOF analysis of 25 years of satellite-measured outgoing longwave radiation data as a proxy for deep convection. The first mode represents a strengthening of the West African monsoon convection. It has an associated global structure and appears to be a remote response to northward-propagating intraseasonal anomalies over the Indian and western Pacific sectors - the northern summer counterpart of the Madden-Julian oscillation. The second mode describes an east-west dipole in convection over Africa. Enhanced convection over West Africa is preceeded by eastward propagation of enhanced convective anomalies from the tropical Atlantic. Reduced convection over East Africa is preceeded by westward propagation from the Indian Ocean, which again is part of the dominant mode of intraseasonal variability over the Indian-western Pacific sector. Patterns of African intraseasonal variability will also be presented for northern winter and underlying physical mechanisms will be discussed.
Supplementary URL: http://envam1.env.uea.ac.uk/~e058/amstropmet2002.pdf
Session 17B, Intraseasonal Variability III (Parallel with Sessions 17A and 17C)
Friday, 3 May 2002, 11:00 AM-12:30 PM
Previous paper Next paper