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GMAO’s Seasonal-to-Interannual Forecasts & Potential contributions to MME Forecasts

GMAO’s Seasonal-to-Interannual Forecasts & Potential contributions to MME Forecasts. Michele Rienecker, Randy Koster , Siegfried Schubert Christian Keppenne, Rolf Reichle, Shu-Chih Yang CTB SAB Meeting August 28, 2007. Max Suarez Global Modeling and Assimilation Office (GMAO).

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GMAO’s Seasonal-to-Interannual Forecasts & Potential contributions to MME Forecasts

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  1. GMAO’s Seasonal-to-Interannual Forecasts &Potential contributions to MME Forecasts Michele Rienecker, Randy Koster, Siegfried Schubert Christian Keppenne, Rolf Reichle, Shu-Chih Yang CTB SAB Meeting August 28, 2007 Max Suarez Global Modeling and Assimilation Office (GMAO) 30 Nov 2005

  2. CGCMv1 Ensemble Forecast System AGCM(AMIP forced with Reynolds SST; NCEP Analyses) 12 month Coupled Integrations: 6-30 ensemble members Atmospheric state perturbations: ’s randomly from previous integrations Ocean state estimate perturbations: ’s randomly from snapshots or from EnKF Ocean DAS(Surface wind analysis, GPCP precipitation; Reynolds SST, Temperature profiles; synthetic salinity profiles; altimetry) AGCM: NSIPP1 AGCM, 2 x 2.5 x L34 LSM: Mosaic (SVAT) OGCM: Poseidon v4, 1/3 x 5/8 x L27, with embedded mixed layer physics CGCM: Full coupling, once per day ODAS: Optimal Interpolation of in situ temperature profiles; Ensemble Kalman Filter “LDAS”: Offline forced land states (recalibrated) 30 Nov 2005

  3. CGCMv1 Forecasts initialized 1 Aug, 2007 30 Nov 2005

  4. Forecast skill (ACC) from CGCMv1 SST anomaly Initialized 1 March, 1993-2006 EnKF OI-TS 1-month lead 3-month lead 6-month lead 30 Nov 2005

  5. Forecast skill (ACC) from CGCMv1 Heat content anomaly in upper 300m Initialized 1 March, 1993-2006 EnKF OI-TS 1-month lead 3-month lead 6-month lead 30 Nov 2005

  6. July Forecast Anomaly Correlation CNT Mean BV Mean BV1 Mean BV2 FEB start MAY start AUG start NOV start 30 Nov 2005

  7. GEOS-5 CGCM Forecast System - Status & Plans • GEOS-5 AGCM, Catchment LSM, MOM4 • Simulation for several decades, still tuning • Configuration • AGCM: 1° 1.25°72L • MOM4: 0.25° 0.5° 40L (telescoping grid in equatorial band - NCEP configuration) • Forecast Initialization • MOM4 initialized by ODAS-2 multivariate assimilation (EnKF) • LSM initialized by offline (LIS) forcing • AGCM initialized by reanalysis (NCEP, MERRA?) • Hindcast strategy • 1993-2007 • Use low-resolution MERRA for atmosphere and also for ocean forcing • Coupled EnKF? • Ensemble Strategy possibilities • mimic NCEP, initialization every day • mimic NCEP (except initialization every 3days) + 3-member ensemble from breeding • all ensemble members initialized 1st of the month 30 Nov 2005

  8. GEOS-5 CGCM- contributing to the MME • GEOS-5 timeline • Q2-FY08 Begin ODAS • Q3-FY08 Begin hindcasts • Q4-FY08 Contribute selected G5 hindcast months to CTB MME • Proposed Interim Strategy • Use CGCMv1 (ensembles initialized 1st month, 1993 - present) • Q1-FY08 contribute EnKF system for selected months as test of MME 30 Nov 2005

  9. CGCMv1 Forecasts initialized 1 Aug, 2007 30 Nov 2005

  10. 30 Nov 2005

  11. Mean SST error in Nino3 Ensemble forecast system performance ACC in Nino3 SST Ensemble spread in Nino3 SST ensemble spread vs.SST error In Nino3 region • Forecast errors show a strong dependence on seasons/starting month • Ensemble spread doesn’t have the season-dependent characteristic shown in forecast errors • Ensemble spread is too small compared to the forecast error, especially at early months error spread Forecast month 30 Nov 2005 Shu-Chih Yang

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