Influence of Surface Processes over Africa on the Atlantic Marine ITCZ and South American Precipitation
Open Access
- 1 December 2005
- journal article
- Published by American Meteorological Society in Journal of Climate
- Vol. 18 (23), 4993-5010
- https://doi.org/10.1175/jcli3586.1
Abstract
Previous studies show that the climatological precipitation over South America, particularly the Nordeste region, is influenced by the presence of the African continent. Here the influence of African topography and surface wetness on the Atlantic marine ITCZ (AMI) and South American precipitation are investigated. Cross-equatorial flow over the Atlantic Ocean introduced by north–south asymmetry in surface conditions over Africa shifts the AMI in the direction of the flow. African topography, for example, introduces an anomalous high over the southern Atlantic Ocean and a low to the north. This results in a northward migration of the AMI and dry conditions over the Nordeste region. The implications of this process on variability are then studied by analyzing the response of the AMI to soil moisture anomalies over tropical Africa. Northerly flow induced by equatorially asymmetric perturbations in soil moisture over northern tropical Africa shifts the AMI southward, increasing the climatological precipitation over northeastern South America. Flow associated with an equatorially symmetric perturbation in soil moisture, however, has a very weak cross-equatorial component and very weak influence on the AMI and South American precipitation. The sensitivity of the AMI to soil moisture perturbations over certain regions of Africa can possibly improve the skill of prediction.Keywords
This publication has 24 references indexed in Scilit:
- The Africa–South America Intercontinental TeleconnectionJournal of Climate, 2004
- The relationship between the Sahelian and previous 2nd Guinean rainy seasons: a monsoon regulation by soil wetness?Annales Geophysicae, 2002
- The Role of Orography in Determining the Sahelian ClimateInternational Journal of Climatology, 1997
- The NCEP/NCAR 40-Year Reanalysis ProjectBulletin of the American Meteorological Society, 1996
- Circulation mechanisms related to northeast Brazil rainfall anomaliesJournal of Geophysical Research: Atmospheres, 1993
- Mean seasonal and spatial variability in gauge‐corrected, global precipitationInternational Journal of Climatology, 1990
- Stationary Barotropic Flow Induced by a Mountain over a Tropical BeltMonthly Weather Review, 1980
- Some simple solutions for heat‐induced tropical circulationQuarterly Journal of the Royal Meteorological Society, 1980
- Numerical experiments on the orographic-dynamic phenomenon over a tropical beltArchiv für Meteorologie, Geophysik und Bioklimatologie Serie A, 1980
- A Numerical Method for Predicting the Perturbations of the Middle Latitude WesterliesTellus, 1949