Dec 13, 2017

The Extreme 2015/16 El Niño, in the Context of Historical Climate Variability and Change

by
Matthew Newman, Andrew T. Wittenberg, Linyin Cheng, Gilbert P. Compo, and Catherine A. Smith
,
Bulletin of the American Meteorological Society
  • Assesses this El Niño–Southern Oscillation (ENSO) event using statistics of Niño3 (5°N–5°S, 150°–90°W) and Niño4 (5°N–5°S, 160°E–150°W) sea surface temperature (SST) indices
  • Derives indices from observational datasets and coupled general circulation model simulations
  • Compares the December 2015 (DEC2015) equatorial SST anomaly (SSTA) to the SSTA distribution during 1891–2000
  • Applies the generalized extreme value distribution to the historical annual maximum of linearly detrended monthly Niño3 and Niño4 indices during 1891–2000
  • Finds that:
    • The 2015/16 El Niño was a strong but not unprecedented warm event in the eastern equatorial Pacific (Niño3), comparable to events occurring every few decades or so
    • However, central equatorial Pacific (Niño4) 2015/16 warmth was unprecedented in all SST reconstruction datasets except ERSST.v4
  • Results show that this exceptional warmth was unlikely to have occurred entirely naturally, and appears to reflect an anthropogenically forced trend