Neural Network Model Forecasts of the NINO3.4 Sea Surface Temperature

contributed by Benyang Tang¹, William W. Hsieh¹ and Fredolin T. Tangang²

¹Department of Earth and Ocean Sciences University of British Columbia, Vancouver, B.C., Canada

²Department of Marine Science, Faculty of Science & Natural Resources, National University of Malaysia

The model we used to produce these forecasts is the same as that appearing in the September 1998 Issue of this bulletin. The reader is referred to that issue for details of our model.

Figure 1 shows the forecasts at leadtimes of 3, 6, 9, and 12-months, using data up to August 1999. Forecasts of the 6- and 12-month leadtimes indicate that the current La Niña conditions in the tropical Pacific will continue into the first few months of year 2000 and return to normal around the middle of the year. Our model has been consistently calling for a La Niña 1999/2000 winter since January, 1999.

Due to an unfortunate computer bug in our data transmission, the forecast skill of our neural network model shown in a recent draft report to the CLIVAR Numerical Experimentation Group by Kirtman et al. was incorrect. The correct cross-validated forecast correlation skill is shown in Table 1 for different test periods.

Table 1. The cross-validated correlation skills for different test periods

Figure captions

Figure 1. Forecasts of the neural networks at 3, 6, 9, and 12-month leadtimes. The solid curve shows the observed values and the circles, the predicted values.