FIGURE F12. Time series of predicted sea surface
temperature anomalies (SSTA) for the Niño 4, Niño 3.4, Niño 3, and
Niño 1+2 indices in °C and the Southern Oscillation Index (SOI) in
standardized deviations based on the ENSO-CLIPER statistical model (Knaff
and Landsea 1997, Wea. Forecasting, 12, 633-652). The
observed three-month average values are shown as a thick line.
Three-month average forecast values are the thick line with horizontal
bars, which indicate the adjusted RMSE. Anomalies are departures from
the 1971–2000 base period for the SSTs and for the 1951–80 base
period for the SOI.