The current El Niño Pacific Ocean warming event is now the strongest El Niño since 1997–98, according to Australia’s Bureau of Meteorology (BoM).
Weekly sea surface temperature (SST) changes. Courtesy BoM.
Conditions in the the tropical Pacific Ocean and in the atmosphere above it are now re-inforcing each other – fully coupled, in the meteorological jargon – in a pattern consistent with persistent El Niño conditions.
Sea surface temperatures are well above El Niño thresholds, acording to BoM. Trade winds are consistently weak and the Southern Oscillation Index, a measure of the atmospheric pressure difference between Tahiti and Darwin, has been strongly negative; these ae both signs of an established El Niño.
Weekly tropical Pacific Ocean temperature anomalies – the variance to average temperatures – in the central Pacific are now at their highest values since 1997–98, though still remain more than half a degree below the peak observed during the 1997–98 El Niño.
Computer climate models indicate the tropical Pacific will continue to warm, with the largest anomalies occurring later in the year. Typically, El Niño peaks during the late austral spring or early summer, and weakens during late summer to autumn. The 2015 event has, so far, been following a normal El Niño life cycle, according to BoM.
Below we reproduce the latest analysis from Australia’s BOM (with graphics on the right):