oni: ONI - Oceanographic Niño Index

In pbs-assess/PACea: An R package of Pacific ecosystem information to help facilitate an ecosystem approach to fisheries management

ONI – Oceanographic Niño Index

Description

The Oceanic Niño Index is a monthly index which is one measure of the El Niño-Southern Oscillation.

Usage

oni

Format

A tibble also of class 'pacea_index' with columns:

year:

year of value

month:

month (1 to 12) of value

val:

absolute values of three-month averages (preceding, current, and next month), deg C; note that recent values may change in subsequent updates – see details

anom:

anomalies based on 30-year base periods that are updated every 5 years, deg C; note that recent values may change in subsequent updates – see details

Details

The Oceanic Niño Index (ONI) is a 3-month running mean of sea surface temperature (SST) anomalies in the Niño 3.4 region (5 deg N to 5 deg S, 120 deg W to 170 deg W) plotted on the center month. The SST anomalies are calculated based on 30-year base periods that are updated every 5 years, which accounts for global warming and some of the decadal-scale SST variability (as seen in the Pacific Decadal Oscillation index). The ONI is provided by the NOAA’s National Weather Service National Centers for Environmental Prediction CPC: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml

Preceding paragraph adapted from: Ross, T., and Robert, M. (2022). Normal temperatures despite strong cool climate indices and an emerging freshening trend. Pages 23-30 of Boldt, J.L., Joyce, E., Tucker, S., and Gauthier, S. (Eds.). 2022. State of the physical, biological and selected fishery resources of Pacific Canadian marine ecosystems in 2021. Canadian Technical Report of Fisheries and Aquatic Sciences. 3482 vii+242 p.

The above website is updated automatically on the first Thursday of each month, and states that:

Because of the high frequency filter applied to the ERSSTv5 data, ONI values may change up to two months after the initial "real time" value is posted. Therefore, the most recent ONI values should be considered an estimate. On the site, Warm (red) and cold (blue) periods are based on a threshold of +/- 0.5 deg C for the Oceanic Niño Index (ONI) [3 month running mean of ERSST.v5 SST anomalies in the Niño 3.4 region (5 deg N-5 deg S, 120 deg W -170 deg W)], based on centered 30-year base periods updated every 5 years. For historical purposes, periods of below and above normal SSTs are colored in blue and red (on the website) when the threshold is met for a minimum of 5 consecutive overlapping seasons. The ONI is one measure of the El Niño-Southern Oscillation, and other indices can confirm whether features consistent with a coupled ocean-atmosphere phenomenon accompanied these periods.

Also see https://www.ncei.noaa.gov/access/monitoring/enso/sst

Associated code adapted from code generously shared by Chris Rooper.

Author(s)

Andrew Edwards

Source

Generated from running 'data-raw/coastwide-indices/coastwide-indices.R'.

Examples

## Not run: 
oni
plot(oni)

## End(Not run)

pbs-assess/PACea documentation built on April 17, 2025, 11:36 p.m.