A POP Model for ENSO Forecasting

Using FSU wind data up to March 1999

Current Forecast

The La Nina condition has peaked. By March 1999, the wind condition is not in any precursor area.

Looking back to the past 5 cold events, we can see 2 categories of movement after the peak of a La Nina: 1) overshoot to the third quadrant (1970, 1975 and 1988), resulting in a normal or warm condition the following winter; 2) move back the inner circle (1973 and 1983), resulting in a somewhat continuous cold condition. The current wind pattern seems to belong to the second category.

Recent (1995, 1996, 1997 and 1998) POP Figures

POP figures for 1998 to 1999
POP illustration

How to read the POP Figure

Using the POP method, the monthly wind stress data of each month in the tropical Pacific are reduced to a complex number, which is displayed as a point in the POP figure. Whenever this point appears in the warm (cold) event precursor area, a warm (cold) event is forecasted to be coming in 6 to 12 months.

Each POP figure represents one-year's wind evolution, with the greenest circle being January of the year and the reddest circle being December of the year. The two '+'s represent January and February of next year. In the 1997 POP figure, the 'x' represents the most recent month whose data has not been filtered.

Reference: Tang, B., 1995: Periods of linear development of the ENSO cycle and POP forecast experiments. J. Climate, 8, 682-691 Abstract

1970 to 1994 POP Figure

POP figures for 1970 to 1981
POP figures for 1982 to 1993
POP figures for 1994 to 1997