An assessment of El Niño and La Niña impacts focused on monthly and seasonal rainfall and extreme dry/precipitation events in mountain regions of Colombia and México

摘要

The influence of El Niño and La Niña on monthly andseasonal rainfall over mountain landscapes in Colombia and México wasassessed based on the Oceanic Niño Index (ONI). A statistical analysiswas develop to compare the extreme dry/precipitation events between ElNiño, La Niña and Neutral episodes. For both areas, it was observedthat El Niño and La Niña episodes are associated with importantincreases or decreases in rainfall. However, Neutral episodes showed thehighest occurrence of extreme precipitation/dry events. For a betterunderstanding of the impact of El Niño and La Niña on seasonalprecipitation, we did a compound and a GIS analyses to define the high/lowprobability of above, below or normal seasonal precipitation under ElNiño, La Niña and cold/warm Neutral episodes. In San Vicente,Colombia the below-normal seasonal rainfall was identified during ElNiño and Neutral episodes in the dry season JJA. In this samemunicipality we also found above-normal seasonal rainfall during La Niñaand Neutral episodes, especially in the dry season DJF. In TancítaroMéxico the below-normal seasonal rainfall was identified during LaNiña winters (DJF) and El Niño summers (JJA), the above-normalseasonal rainfall was found during La Niña summers (JJA) and El Niñowinters (DJF).