Early Successes: El Nino, Southern Oscillation and Seasonal Forecasting
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Comparison is made between events surrounding the 1982/3 El Niņo and the 1997/8 El Niņo. The lack of a coherent appreciation of the development in the early stages of the 82/3 El Niņo lead to the formation of TOGA, Tropical Ocean Global Atmosphere, a 10 year experiment from 1985 which saw the foundation of a comprehensive observing system for the tropical Pacific that has since expanded to cover the tropical Atlantic and is now being extended to the Indian Ocean. With such an observation array in place providing high quality data, the 97/8 El Niņo was well captured. Provided the quality of the data obtained while it was a research array can be maintained now that it has operational status, it is highly unlikely that any El Niņo or La Niņa could sneak up unobserved. Of course, seasonal prediction is about more than just predicting extreme El Niņos. The overall skill spanning the period from 1981 is considered.
Considerable progress has been made in ocean analyses. This is partly the development of much more mature models and assimilation schemes but partly because of better quality surface fluxes obtained from atmospheric reanalyses. Seasonal forecast skill has also improved over the last 15 years as coupled atmosphere ocean models and ocean analyses have improved. Observing system experiments are used to show the importance of the TAO/TRITON/PIRATA (Tropical Atmosphere Ocean/Triangle Trans-Ocean Buoy Network/Prediction and Research Moored Array in the Atlantic) mooring system as well as altimetry. It is less easy to show statistically significant impact of the Argo (Array for Real-time Geostrophic Oceanography) data on forecast skill at this stage since the Argo period is quite short compared to that of the variability of ENSO (El Niņo/Southern Oscillation).
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This paper shall be cited as:
Anderson, D. (2010). "Early Successes: El Nino, Southern Oscillation and Seasonal Forecasting " in Proceedings of OceanObs’09: Sustained Ocean Observations and Information for Society (Vol. 1), Venice, Italy, 21-25 September 2009, Hall, J., Harrison, D.E. & Stammer, D., Eds., ESA Publication WPP-306, doi:10.5270/OceanObs09.pp.01
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