Mapping ENSO: Precipitation for the US-Affiliated Pacific Islands

EarthzineAssessing Drought and Water Availability, DEVELOP 2015 Summer VPS, DEVELOP Virtual Poster Session

This is an article from the Summer 2015 VPS. For more VPS articles, click here


Average winter (December, January and February) precipitation anomalies during moderate-strong La Ni̱a events (A) and El Ni̱o events (C). Average 30-year winter precipitation (B). Image Credit: Pacific Water Resources Team

Category:åÊAssessing Drought and Water Availability

Project Team: Pacific Water Resources

Team Location: NOAA National Centers for Environmental Information (NCEI) – Asheville, North Carolina


Jessica Sutton

Nicolas Luchetti

Ethan Wright


Michael Kruk (Earth Resources Technology [ERT])

John Marra (NOAA Regional Climate Services, Pacific Region)


The United States Affiliated Pacific Islands (USAPI) are highly susceptible to extreme precipitation events such as drought and flooding, which directly affect their freshwater availability. Precipitation distribution differs by sub-region, and is predominantly influenced by phases of the El Ni̱o Southern Oscillation (ENSO). Forecasters currently rely on ENSO climatologies from sparse in-situ station data to inform their precipitation outlooks. This project provided an updated ENSO-based climatology of long-term precipitation patterns for each USAPI Exclusive Economic Zone (EEZ) using the NOAA PERSIANN Climate Data Record (CDR). This data provided a 30-year record (1984-2015) of daily precipitation at 0.25-degree resolution, which was used to calculate monthly, seasonal, and yearly precipitation. Results indicated that while the PERSIANN precipitation accurately described the monthly, seasonal, and annual trends, it under-predicted the precipitation on the islands. Additionally, maps showing percent departure from normal (30-year average) were made for each three month season based on the Oceanic Ni̱o Index (ONI) for five ENSO phases (moderate-strong El Ni̱o and La Ni̱a, weak El Ni̱o and La Ni̱a, and neutral). Local weather service offices plan on using these results and maps to better understand how the different ENSO phases influence precipitation patterns.

Previous story / Next story