Disentangling the Impact of ENSO and Indian Ocean Variability on the Regional Climate of Bangladesh: Implications for Cholera Risk

Abstract Recent studies arising from both statistical analysis and dynamical disease models indicate that there is a link between the incidence of cholera, a paradigmatic waterborne bacterial illness endemic to Bangladesh, and the El Nino–Southern Oscillation (ENSO). Cholera incidence typically increases following boreal winter El Nino events for the period 1973–2001. Observational and model analyses find that Bangladesh summer rainfall is enhanced following winter El Nino events, providing a plausible physical link between El Nino and cholera incidence. However, rainfall and cholera incidence do not increase following every winter El Nino event. Substantial variations in Bangladesh precipitation also occur in simulations in which identical sea surface temperature (SST) anomalies are prescribed in the central and eastern tropical Pacific. Bangladesh summer precipitation is thus not uniquely determined by forcing from the tropical Pacific, with significant implications for predictions of cholera risk. Nonp...

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