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File: relative-vs-regular-SSTA-tropical-Pacific-Aug9-Aug15-2026.png

Maps of tropical Pacific sea surface temperatures comparing traditional anomalies to NOAA's new relative anomaly

(top) NOAA's new yardstick for measuring the strength of El Niño and La Niña compares sea surface temperatures in the tropical Pacific first to the long-term average (1991-2020) and then to the average anomaly across the whole tropics. (bottom) The original yardstick only compared current temperatures to the long-term average. See the difference? The warm anomaly (red, oranges) in the central/eastern Pacific gets a little weaker—we've removed some of the influence of long-term global warming—but it's more obvious that the area is significantly warmer than the western part of the basin (blue). Climate.us image, based on NOAA OISST data.