Observing and Analyzing Variations of Daily Precipitation: The Impact of the El Niño/Southern Oscillation on Kiritimati Island

In 2016, a very strong El Niño increased the amount of precipitation measured on Kiritimati Island (2 °N, 157.4 °W) during the El Niño Rapid Response (ENRR) field campaign. ENRR collected surface meteorological data on Kiritimati Island from January through March 2016. This project focuses on the daily precipitation data collected from 1971 through 2016 during the time of year when ENRR took place and it evaluates how the El Niño/Southern Oscillation (ENSO) influences the daily rainfall distribution on Kiritimati Island. We analyzed daily rainfall measurements from the freshwater lens automated weather station, Decca, and the official Kiribati Meteorological Service station at Cassidy International Airport (PLCH). The long-term data from PLCH provides a historical context from 1971-1990, 1996-2003, 2015-2016, which allows for the study of the distribution of daily rainfall on the island, i.e. how much rain falls into different categories with respect to the total amount of rain measured. We investigated the distribution of daily rainfall on the island during different phases of the ENSO phenomena by generating and analyzing two types of plots: time series and probability density functions (PDFs). The plots were made from the three data collection sites (PLCH, Decca, and CXENRR, the Kiritimati Island ENRR location.) This presentation will explain how rainfall on Kiritimati Island during an El Niño differs from rainfall during a La Niña and the neutral phase of ENSO.