The influence of El Niño phenomenon on the climate of Venezuela

Guevara, Edilberto, author
Colorado State University, publisher
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Annual rainfall distribution in tropical America depends on the ITC zone, affected by factors such as Andes Mountain, tropical Pacific and Atlantic Oceans and local convergence areas. Studies have showed correlation between the ENSO Phases and hydrologic anomalies in the region. In Venezuela ENSO effects are reflected as climatic anomalies with magnitudes varying within the areas. This paper deals with the study of the effects of El Niño phenomena on the climatic variables in Venezuela. Variables affected directly by El Niño are rainfall, temperature and flows. Indirectly consequences are associated with an increase of diseases such Malaria, Dengue and Cholera. ENSO phenomena create anomalies in Hadley cells over Venezuela originating negative anomalies for rainfall during El Niño years and positive rainfall anomalies during La Niña events. Results of correlations between this anomalies and SSTA-3/4 have show negative rainfall anomalies between 8 and 20 % and positive anomalies of 14 to 30 %, depending on the region. About 85 % of ENSO years coincide with rainfall deficits bigger than 35 %. Temperature values are less sensitive to the occurrence of El Niño, varying the magnitude of the anomalies between 0.5 °C to 1 °C, high enough to increase the transmission of Dengue in a rate of 100 %. Malaria mortality and mobility increases in 37 % the year after an El Niño event. The relationship between ENSO 3/4 Indices and flow anomalies of Caroní River shows that the join occurrence of atmospheric and oceanic events exercise the biggest influence on the occurrence of flow anomalies in this basin. During the cold El Niño period in the Pacific (La Niña) flows in Caroni basin diminish affecting the storage and level of operation of Guri reservoir and the production of hydro electrical energy. In fact, 12 from the 15 El Niño events that happened during the analyzed period of flows (1950-2004) coincide with years in which mean annual flow is far smaller than the historical mean.
2006 annual AGU hydrology days was held at Colorado State University on March 20 - March 22, 2006.
Includes bibliographical references.
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climatic anomalies
ENSO in Venezuela
effect of El Niño in Venezuela
influence of ENSO on the climate of Venezuela
effects of tele-connections
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