Introduction to El Niño phenomena: a Peruvian perspective

Abstract

The recent interest in El Niño Phenomenon stems from: 1) our better understanding of the physical processes involved, which in turn has made possible its early prediction, 2) the realization that it affects the climate at a global scale, and 3) its unusual recent intense episodes and their higher frequency of occurrence. The behavior of EI Niño during the 1997-98 cycle was successfully predicted with six or more months in advance. From an equatorial eastern-Pacific point of view, more specifically from the long tradition and historical records available in Piura, Peru (-5ºS, 79°W), the 1997-98 and the 1982-83 El Niño have been the strongest recorded in the last 470 years, i.e., since the Spanish foundation of the city. Piura is the oldest post-Hispanic city in the whole South American continent and the most sensitive to El Niño related climatic variations. While the phenomena have only recently caught the attention of the world, its existence was well known by the local population. In fact, the name, El Niño (Christ Child), was coined by the fishermen of the area, with the believe that the warm waters associated with the phenomena carne with the northern current which appeared around Christmas time. The author was born and brought up in Piura. This may explain why an upper-atmospheric physicist has been invited to give a talk on the subject. Climatologists have come to realize that, after the well-known seasonal variations, the most important "predictable" climatic variations are the inter-annual ones related to El Niño. Its statistical signature can be observed far beyond the coastal areas around the equatorial Pacific and includes the effects on the climate of the Australian and whole American continent, the Asían monsoons and the frequency and intensity of hurricanes in the Caribbean, to mention a few.