download_roni: Download Relative Oceanic Nino Index data

In rsoi: Import Various Northern and Southern Hemisphere Climate Indices

Download Relative Oceanic Nino Index data

Description

El Niño–Southern Oscillation (ENSO) is often characterized through the use of sea surface temperature (SST) departures from their climatological values, as in the Niño-3.4 index. However, this approach is problematic in a changing climate when the climatology itself is varying. To address this issue, van Oldenborgh et al. proposed a relative Niño-3.4 SST index, which subtracts the tropical mean SST anomaly from the Niño-3.4 index and multiplies by a scaling factor.

• The cold phase was defined as periods in which the RONI values within a sliding five-season window were all below -0.5 degC

• The warm phase was defined as periods in which the RONI values within a sliding five-season window were all above 0.5 degC

• The neutral phase was defined as the situation outside the definitions of warm phase and cold phase

Usage

download_roni(use_cache = FALSE, file = NULL)

Arguments

use_cache	logical option to save and load from cache. If 'TRUE', results will be cached in memory if 'file' is 'NULL' or on disk if 'file' is not 'NULL'.
file	optional character with the full path of a file to save the data. If 'cache' is 'FALSE' but 'file' is not 'NULL', the results will be downloaded from the internet and saved on disk.

Value

• Year: Year of record

• Season: Season of record

• roni: Relative Oceanic Niño Index, using the 1991–2020 base period "3 month running mean of ERSST.v5 SST anomalies in the Niño 3.4 region (5°N–5°S, 120°–170°W) with average tropical mean (20°N–20°S) SST anomalies subtracted. The difference is then adjusted so the variance equals the original Niño 3.4 index".

• Start_Month: Start month of record

• End_Month: End month of record

• phase: ENSO phase

References

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/#latest-data \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1175/JCLI-D-23-0406.1")}

Examples

## Not run: 
roni <- download_roni()

## End(Not run)

rsoi documentation built on March 13, 2026, 9:07 a.m.