Spatial and temporal effects of El Niño in Philippine rainfall and cyclones
2006
de los Reyes, R.B. | David , W.P., Philippines Univ. Los Banos, College, Laguna (Philippines). Land and Water Resources Div.
Seven El Niño events (1997-98,1994-95,1990-93,1986-88, 1982-83, 1977-78,and 1972-73) was studied to determine their effects on rainfall and tropical cyclones in the Philippines. Percent deviation from the mean monthly rainfall and the number and tracks of tropical cyclones were mapped with the aid of an ArcView GIS software to show the spatial and temporal effects of each event. The results showed that the effect of each El Niño event on monthly rainfall and the tropical cyclones is unique and depends on its intensity,location, area coverage,duration and time occurrence. Nevertheless, some general patterns can be observed. The effect of El Niño on rainfall is initially felt 3-5 mo after the development of warm episode in the tropical Pacific. Recovery from El Niño starts in Mindanao (then moves in the northeasterly direction) when the sea surface temperature (SST) in the tropical Pacific returns to normal. The monthly rainfall received in most parts of the country was reduced by more than 50% during the peak of a strong event. Strong El Niño events suppressed tropical cyclone activity while weak-to-moderate events did not, but shifted northeast the tracks of tropical cyclones. Information generated in this study will help decision makers and planners formulate appropriate intervention measures to cope with the adverse effect of El Niño on agriculture and assess the vulnerability to El Niño induced drought of important agricultural commodities in the different agroecological zones of the country.
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