El Ni ˜ no - related precipitation variability in Per ´ u

The relationship between monthly mean sea sur- face temperature (SST) anomalies in the commonly used El Ni˜ no regions and precipitation for 44 stations in Per ´ u is doc- umented for 1950-2002. Linear lag correlation analysis is employed to establish the potential for statistical precipita- tion forecasts from SSTs. Useful monthly mean precipitation anomaly forecasts are possible for several locations and cal- endar months if SST anomalies in El Ni˜ no 1+2, Ni˜ Peru coast and to planetary-scale changes in the tropical at- mosphere, the "Southern Oscillation". In subsequent years, the term "El Ni ˜ no" has been used in the literature to describe basin-scale equatorial Pacific warm- ings, and this has blurred the distinction with the coastal phenomenon, which while related to does not exhibit a one- to-one correspondence with the basin-scale SST variability (Rasmusson and Carpenter, 1982; Deser and Wallace, 1987; Trenberth and Stepaniak, 2001). This usage has lead to con- fusion and contradictions in the use of the term "El Ni ˜ no"