El Nino/La Nina relationship with rainfall at Huancayo, in the Peruvian Andes

The major rainy season at Huancayo (central Peruvian Andes) is in the month s DJFM (December-March). For years when El Ninos were active during these m onths, two types of effects were noticed. Either there were rainfall defici ts in the DJF months, or there were excess rains in DJ, followed and preced ed by deficit rains for a month or two. When El Ninos were active in other months, the non-rainy season rainfall at Huancayo was sometimes far above a verage. During years of La Nina (Anti-El Ninos), there were often excess ra ins, in both the rainy and the non-rainy seasons. In coastal Peru, heavy ra infall is considered as one of the criteria for identifying an El Nino. If true, the rainfall patterns at Huancayo are different from those of coastal Peru. In the recent El Nino of 1997, southern Peru had droughts while east ern and northern Peru, Ecuador had floods. The ENSO relationships in differ ent parts of Peru are probably different and need detailed investigation. C opyright (C) 2000 Royal Meteorological Society.