Large-Scale Climate Variability Patterns and Drought: A Case of Study in South – America

Abstract

Droughts are complex phenomena that can affect highly the development of a region due to the reduction of the availability of water with various degrees of severity, duration, and extent. Large-scale climatic variability patterns such as El Nino South Oscillation (ENSO), Atlantic Multidecadal Oscillation (AMO) and Pacific Decadal Oscillation (PDO) can trigger droughts as they alter normal precipitation patterns. Drought indices simplify the analysis of the complex interrelationships between the different climatic parameters that influence the occurrence of droughts, allowing the quantitative evaluation of anomalies in terms of intensity, duration, frequency, and spatial extent. The Standard Precipitation Index (SPI) is one of the most used for its simplicity and accuracy. The aim of this paper is to study the possible teleconnections between ENSO, AMO and PDO and the occurrence of droughts in Ecuador - South America, a very poorly studied area of the world, and to contribute to planning and decision making in the management of water resources in this country in a short and long term. The SPI was calculated for each month (monthly scale) for a period of 44 years and spatialized by Kriging interpolation to later be related to the ONI, AMO and PDO indices using a one-way ANOVA test. It was determined that there is a greater occurrence of droughts when the PDO is in the negative phase. The occurrence of droughts is also significant when the ENSO, in the neutral phase, and the PDO, in the negative phase, take place simultaneously. The AMO showed an insignificant influence.