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

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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). - PowerPoint PPT Presentation

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

  • GMAOs Seasonal-to-Interannual Forecasts &Potential contributions to MME ForecastsMax SuarezGlobal Modeling and Assimilation Office (GMAO)

    Michele Rienecker, Randy Koster, Siegfried SchubertChristian Keppenne, Rolf Reichle, Shu-Chih Yang

    CTB SAB MeetingAugust 28, 2007

    30 Nov 2005

  • 12 month Coupled Integrations: 6-30 ensemble membersAGCM (AMIP forced with Reynolds SST; NCEP Analyses)Ocean DAS (Surface wind analysis, GPCP precipitation; Reynolds SST, Temperature profiles; synthetic salinity profiles; altimetry)Ocean state estimate perturbations:s randomly from snapshots or from EnKFAtmospheric state perturbations: s randomly from previous integrationsAGCM: NSIPP1 AGCM, 2 x 2.5 x L34LSM: Mosaic (SVAT)OGCM: Poseidon v4, 1/3 x 5/8 x L27, with embedded mixed layer physicsCGCM: Full coupling, once per day

    ODAS: Optimal Interpolation of in situ temperature profiles; Ensemble Kalman FilterLDAS: Offline forced land states (recalibrated)CGCMv1 Ensemble Forecast System

    30 Nov 2005

  • CGCMv1 Forecasts initialized 1 Aug, 2007

    30 Nov 2005

  • 1-month lead3-month lead6-month leadEnKF OI-TS Forecast skill (ACC) from CGCMv1SST anomalyInitialized 1 March, 1993-2006

    30 Nov 2005

  • 1-month lead3-month lead6-month leadEnKF OI-TS Forecast skill (ACC) from CGCMv1Heat content anomaly in upper 300mInitialized 1 March, 1993-2006

    30 Nov 2005

  • July Forecast Anomaly Correlation

    30 Nov 2005

  • GEOS-5 CGCM Forecast System - Status & Plans GEOS-5 AGCM, Catchment LSM, MOM4 Simulation for several decades, still tuning

    Configuration AGCM: 1 1.2572L 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

  • 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

  • CGCMv1 Forecasts initialized 1 Aug, 2007

    30 Nov 2005

  • 30 Nov 2005

  • Forecast errors show a strong dependence on seasons/starting month Ensemble spread doesnt have the season-dependent characteristic shown in forecast errors Ensemble spread is too small compared to the forecast error, especially at early monthsSST ensemble spread vs. SST errorIn Nino3 regionSST Ensemble spread in Nino3 errorspreadForecast monthShu-Chih YangACC in Nino3 Ensemble forecast system performance

    30 Nov 2005

    Ocean assimilation is Optimal interpolation, conducted daily with the global in situ temperature databaseSalinity is adjusted commensurate with the temperature adjustments and the models water massesRandom perturbations are generated from differences between randomly selected snapshots for the ocean and for the atmosphere. For the ocean these differences are applied with a randomly generated amplitude (usually 0 - 0.2)

    Current real-time forecasts use 19 ensemble members: a mixture of ocean-only and atmosphere-only perturbations, with (in addition) one set of 6 ocean perturbations forced by a single atmospheric perturbation.Land is initialized only through AMIP

    Bred vectors showing greater skill later in the forecast (see August start). The bred vectors based on the depth of the 20C isotherm (BV2) shows greater improvements than those based on SST. Still have a disconnect with eastern bdry.The growth of the ensemble perturbations are not optimized or not effectively represent the system uncertainties