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Dynamics of El Ni ño – Southern Oscillation

This study examines the persistence of surface wind and pressure anomalies near the Equator and its impact on historical analyses of instrumental data. It explores the drivers of this persistence and the benefits it offers for ocean modeling. The research also discusses the use of persistence in constraining historical analyses and the suitability of wind analyses for driving ocean models.

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Dynamics of El Ni ño – Southern Oscillation

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  1. Dynamics of El Niño – Southern Oscillation

  2. Persistence of marine tropical climate and El Niño historical reconstructions Alexey Kaplan and Daniel Gombos LDEO Cornell University In collaboration with : J.CH. Chiang (U of CA, Berkeley), Y.Kushnir, R.Seager, H.-P.Huang (LDEO)

  3. Outline • Why climate persistence is important for historical analyses of instrumental data? • Surprising persistence of tropical wind and pressure anomalies. • What drives it? • Additional benefit of equatorial wind persistence for ocean modeling. • New horizons opening to us.

  4. EOFs of zonal wind anomaly

  5. Independent ENSO indices

  6. Persistence in SST anomalies is traditionally used to constrain historical analyses,but there is no persistence in monthly wind or pressure anomalies, right?

  7. Persistence: Anomaly autocorrelations with 1 month lag

  8. Persistence: Anomaly autocorrelations with 1 month lag

  9. Persistence with longer lags Zonal wind in Reanalysis: 160E-120W averages

  10. Verification by satellite data

  11. Persistence in AMIP experiments:zonal wind anomaly

  12. John Chiang’s [et al., 2001] approach to surface wind modeling:linearized dynamical core of a GCM [Seager and Zebiak, 1995] is set up to take both sea surface temperature and elevated atmospheric heating as forcings.The latter is parameterized via precipitation.

  13. Persistence of the actual forcings

  14. Simulation skill Consistency of persistence pattern in ERS (colors) and simulation (contours)

  15. What is a good wind product from Oceanographer’s point of view?

  16. Why equatorial persistence?

  17. RMS of sea level response to the wind noise in a single location

  18. Conclusions • Within ~10 degree of Equator there is a persistence of surface wind and pressure anomalies. • It is driven by the persistence in SST and precipitation (via elevated heating). • It can be used in historical analyses of instrumental data by either fitting AR model to wind or pressure data or by including temperature and precipitation in the analysis. • Wind analyses suitable driving ocean models must be persistent near Equator.

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