Thursday, 13 January 2005
Correlation of West African ITCZ position to satellite-derived precipitation based on MEI-evaluated ENSO patterns
Using the Multivariate ENSO Index (MEI) as a discriminator between global El Nino and La Nina events, correlations between monthly West African ITCZ and satellite-derived rainfall are explored and interpreted. Three datasets are used in the study, the first a 1995-present daily Intertropical Convergence Zone product created by hand analysis of surface dewpoint and modeled wind outputs over the African Sahel. These ITCZ positions are compared to outputs of the NOAA Climate Prediction Center’s Africa rainfall Climatology (CPC ARC) that merges surface rain gauge fields with satellite-estimated Meteosat data to obtain daily high resolution gridded precipitation estimates over the African continent. Finally, the Climate Diagnostic Center’s MEI, using principal component analysis of one mid-atmosphere and five surface tropical Pacific parameters to estimate ENSO, is applied to investigate ITCZ-precipitation trends in relation to the state of the global climate. Focusing on an area that is particularly susceptible to food security problems stemming from erratic and anomalous monsoonal precipitation, the West African Sahel is closely examined in this study. It is the intent of the project to determine the interrelationship between the three stated factors such that a more accurate long-lead hydrological forecast may be provided to interested parties in humanitarian organizations.
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