Observations for


Probability of Seasonal Temperature Tercile Conditioned on ENSO

This map shows the historical probability (given in percentile) of seasonal average monthly minimum or maximum temperature falling within the upper (hot), middle (normal), or bottom (cold) one-third ("tercile") of the 1981-2013 historical distribution in the region given the state of ENSO (El Niño, Neutral, La Niña) during the same season.

Here, the ENSO state for each season is defined according to the Oceanic Niño Index (ONI). It is calculated using Sea Surface Temperature (SST) anomalies, based on centered 30-year base periods updated every 5 years, in the geographical box (170˚W, 5˚S, 120˚W, 5˚N). A season is considered El Niño (La Niña) if it is part of at least 5 consecutive overlapping 3-month long seasons where the ONI is above 0.5˚C (below -0.5˚C). Use the controls on the page to select the season, temperature tercile category of interest, and ENSO state. The analysis reproduces, using same SST dataset, the following definition from NOAA

Clicking on the map will then display, for the selected point, yearly seasonal temperature averages time series. The colors of the bars depict what ENSO phase it was that year, and the horizontal lines show the historical terciles limits. This allows to quickly picture what years fell into what ENSO Phase and into what Temperature Tercile category.

NB: This is not a forecast. It is based just on historical observations of temperature and SST. However, it would be a good tool for exploring the effect of different ENSO phases on seasonal rainfall.

Reference for ENSO phases definition: V. E. Kousky and R. W. Higgins, 2007: An Alert Classification System for Monitoring and Assessing the ENSO Cycle. Wea. Forecasting, 22, 353–371. doi: http://dx.doi.org/10.1175/WAF987.1

Dataset Documentation

Climatic Research Unit (CRU) Time-Series (TS) Version 3.22 (CRU TS3.22).

How to use this interactive map


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