GMAOs SeasonaltoInterannual Forecasts Potential contributions to MME Forecasts
GMAO’s Seasonal-to-Interannual Forecasts & Potential contributions to MME Forecasts Max Suarez Global Modeling and Assimilation Office (GMAO) Michele Rienecker, Randy Koster, Siegfried Schubert Christian Keppenne, Rolf Reichle, Shu-Chih Yang CTB SAB Meeting August 28, 2007 30 Nov 2005
CGCMv 1 Ensemble Forecast System AGCM (AMIP forced with Reynolds SST; NCEP Analyses) Atmospheric state perturbations: ’s randomly from previous integrations 12 month Coupled Integrations: 6 -30 ensemble members Ocean state estimate perturbations: ’s randomly from snapshots or from En. KF Ocean DAS (Surface wind analysis, GPCP precipitation; Reynolds SST, Temperature profiles; synthetic salinity profiles; altimetry) AGCM: NSIPP 1 AGCM, 2 x 2. 5 x L 34 LSM: Mosaic (SVAT) OGCM: Poseidon v 4, 1/3 x 5/8 x L 27, 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
CGCMv 1 Forecasts initialized 1 Aug, 2007 30 Nov 2005
Forecast skill (ACC) from CGCMv 1 SST anomaly Initialized 1 March, 1993 -2006 En. KF OI-TS 1 -month lead 3 -month lead 6 -month lead 30 Nov 2005
Forecast skill (ACC) from CGCMv 1 Heat content anomaly in upper 300 m Initialized 1 March, 1993 -2006 En. KF OI-TS 1 -month lead 3 -month lead 6 -month lead 30 Nov 2005
July Forecast Anomaly Correlation CNT Mean BV FEB start MAY start AUG start NOV start 30 Nov 2005 Mean BV 1 Mean BV 2
GEOS-5 CGCM Forecast System - Status & Plans q GEOS-5 AGCM, Catchment LSM, MOM 4 • Simulation for several decades, still tuning q Configuration • AGCM: 1° 1. 25° 72 L • MOM 4: 0. 25° 0. 5° 40 L (telescoping grid in equatorial band - NCEP configuration) q Forecast Initialization • MOM 4 initialized by ODAS-2 multivariate assimilation (En. KF) • LSM initialized by offline (LIS) forcing • AGCM initialized by reanalysis (NCEP, MERRA? ) q Hindcast strategy • 1993 -2007 • Use low-resolution MERRA for atmosphere and also for ocean forcing • Coupled En. KF? q Ensemble Strategy possibilities • mimic NCEP, initialization every day • mimic NCEP (except initialization every 3 days) + 3 -member ensemble from breeding • all ensemble members initialized 1 st of the month 30 Nov 2005
GEOS-5 CGCM- contributing to the MME q GEOS-5 timeline • Q 2 -FY 08 Begin ODAS • Q 3 -FY 08 Begin hindcasts • Q 4 -FY 08 Contribute selected G 5 hindcast months to CTB MME q Proposed Interim Strategy • Use CGCMv 1 (ensembles initialized 1 st month, 1993 - present) • Q 1 -FY 08 contribute En. KF system for selected months as test of MME 30 Nov 2005
CGCMv 1 Forecasts initialized 1 Aug, 2007 30 Nov 2005
30 Nov 2005
Ensemble forecast system performance ACC in Nino 3 Mean SST error in Nino 3 SST ensemble spread vs. SST error In Nino 3 region SST Ensemble spread in Nino 3 • Forecast errors show a strong dependence on seasons/starting month error • Ensemble spread doesn’t have the season-dependent characteristic shown in forecast errors spread • Ensemble spread is too small compared to the forecast error, especially at early months Forecast month 30 Nov 2005 Shu-Chih Yang
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