Forecasting El Niño
P. Chang, R. Saravanan, L. Ji and X. Tang
Departments of Atmospheric Science & Oceanography
El Niño-Southern Oscillation is the major cause of inter-annual variation in the tropical climate Weather is unpredictable beyond two-weeks, acting as noise rendering El Niño cycles. A large ensemble of prediction experiments with a climate model performed on Hydra shows that removing weather noise leads to an improved El Niño forecast skill.
The two panels below show the correlations between predicted and observed ocean temperature changes for 1-11 month forecasts. The forecasts with noise filtering (left panel) show considerable higher correlation than the forecasts without noise filtering (right panel).
The climate model consists of a global atmospheric general circulation model with 2.8x2.8° resolution and an ocean model with 2x1° resolution. The model scales well up to 32 CPUs. A forecast experiment consists of an ensemble of 12 runs.