Precipitation (Gridded) Conditioned on ENSO

This figure shows the historical probability of seasonal precipitation totals falling within the upper (wet) one-third, or bottom (dry) one-third of the historical (1951-2022) distribution given the state of ENSO (El Niño, La Niña) during that same season.

The state of ENSO at a seasonal time scale is represented by the NOAA CPC oceanic Niño index (ONI). The ONI is the seasonal mean of the monthly Niño-3.4 index. Following the CPC, the monthly Niño-3.4 index is the monthly mean sea surface temperature anomaly in the central equatorial Pacific (5˚N–5˚S, 170˚–120˚W).

The resulting impact maps show historical empirical probabilities that have been masked for robust impacts, providing a measure of the effect of ENSO on precipitation while still accounting for statistical significance. The statistical significance of above- or below- normal signal is determined according to a hypergeometric test with the sample sizes determined by the number of El Niño or La Niña events and total years with sufficient data.

Use the controls above the figure to select the season, ENSO state, precipitation category, and significance level of interest.

Reference:

Lenssen, N. J. L., Goddard, L., Mason, S. (2020). Seasonal Forecast Skill of ENSO Teleconnection Maps, Weather and Forecasting, 35(6), 2387-2406.

Dataset Documentation

Probability Data

Data

IRI teleconnection probability data

Data Source

IRI Analyses ENSO-RP

Precipitation Data

Data

1951-2022 monthly gridded (0.5° lat/lon resolution) precipitation totals for global land areas

Data Source

University of East Anglia (UEA) Climatic Research Unit (CRU) TS4.07 dataset Data Library entry

SST Data

Data

Data Source

Extended reconstructed sea surface temperature (ERSSTv5)

Analysis

The state of ENSO at a seasonal time scale is represented by the NOAA CPC oceanic Niño index (ONI). The ONI is the seasonal mean of the monthly Niño-3.4 index. Following the CPC, the monthly Niño-3.4 index is the monthly mean sea surface temperature anomaly in the central equatorial Pacific (5˚N–5˚S, 170˚–120˚W)

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