Forecast of Tropical Pacific SST using an intermediate

Ocean and a statistical atmosphere model

contributed by In-Sik Kang¹, Chung-Kyu Park², and Jong-Seong Kug¹

1School of Earth Environmental Sciences, Seoul National University, Seoul 151-742, Korea

^{2Korea Meteorological Administration, Seoul 156-720, Korea}

El Niño prediction for Jun. 2000 May 2001 has made using the KMA/SNU ENSO prediction system (Kang and Kug, 2000). The system is based on the intermediate ocean and statistical atmosphere model. The ocean model differs from the Cane and Zebiak (1987) model in the parameterization of subsurface temperature and the basic state. The statistical atmosphere model is developed based on the singular value decomposition (SVD) of wind stress and SST. The initialization of the model is done by combining observed SST and wind stress. In addition, the present prediction is attended with random noise to consider weather noise and to generate many sets of prediction. Our approach for random noise is similar to Kirtman and Schopf (1998). The Ensemble prediction is made based on the 20 predictions with the random noise.

Figure 1 shows the Nino3 SST forecast with 12 month lead, without noise (thick dashed line) and with random noise (thin solid lines). The thick solid line indicates ensemble mean of 20 forecast with random noise. The forecast without noise indicates that positive SST gradually develop for next 12 month, while the forecast with noise indicate that the Nino3 SST persists normal or weak positive state. Figure 2 shows the seasonal SST forecast in tropical Pacific basin for Jun. 2000 May 2001. Forecast result indicates that negative SST anomalies will disappear in the central Pacific until this summer and positive SST anomalies appear and develop in the eastern Pacific.

Reference:

Cane, M. A., S. E. Zebiak, 1987: Prediction of El Niño events using a physical model, In Atmospheric and Oceanic

Variability, H. Cattle, Ed., Royal Meteorological Society press, 153-182

Kang, I.-S. and J.-S. Kug, 2000: An El-Niño prediction system with an intermediate ocean and statistical atmosphere model, Geophys. Res. Lett. 27, 1167-1170.

Kirtman, B. P. and P. S. Schopf, 1998: Decadal variability in ENSO predictability an prediction, J. Climate, 11, 2804-2822