30 Nov 2005

GMAO’s Seasonal-to-Interannual Forecasts &

Potential contributions to MME Forecasts

Max 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 members

AGCM (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 EnKF

Atmospheric state perturbations: ’s randomly from previous integrations

AGCM: 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 Filter“LDAS”: Offline forced land states (recalibrated)

CGCMv1 Ensemble Forecast SystemCGCMv1 Ensemble Forecast SystemCGCMv1 Ensemble Forecast SystemCGCMv1 Ensemble Forecast System

30 Nov 2005

CGCMv1 Forecasts initialized 1 Aug, 2007CGCMv1 Forecasts initialized 1 Aug, 2007CGCMv1 Forecasts initialized 1 Aug, 2007CGCMv1 Forecasts initialized 1 Aug, 2007

30 Nov 2005

1-month lead

3-month lead

6-month lead

EnKF OI-TS

Forecast skill (ACC) from CGCMv1SST anomaly

Initialized 1 March, 1993-2006

Forecast skill (ACC) from CGCMv1SST anomaly

Initialized 1 March, 1993-2006

30 Nov 2005

1-month lead

3-month lead

6-month lead

EnKF OI-TS

Forecast skill (ACC) from CGCMv1Heat content anomaly in upper 300m

Initialized 1 March, 1993-2006

Forecast skill (ACC) from CGCMv1Heat content anomaly in upper 300m

Initialized 1 March, 1993-2006

30 Nov 2005

July Forecast Anomaly Correlation

MAYstart

FEBstart

AUGstart

NOVstart

CNT Mean BV Mean BV1 Mean BV2

30 Nov 2005

GEOS-5 CGCM Forecast System - Status & PlansGEOS-5 CGCM Forecast System - Status & PlansGEOS-5 CGCM Forecast System - Status & PlansGEOS-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

GEOS-5 CGCM- contributing to the MMEGEOS-5 CGCM- contributing to the MMEGEOS-5 CGCM- contributing to the MMEGEOS-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, 2007CGCMv1 Forecasts initialized 1 Aug, 2007CGCMv1 Forecasts initialized 1 Aug, 2007CGCMv1 Forecasts initialized 1 Aug, 2007

30 Nov 2005

30 Nov 2005

• 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

SST ensemble spread vs. SST errorIn Nino3 region

Mean SST error in Nino3 SST Ensemble spread in Nino3

error

spread

Forecast month

Shu-Chih Yang

ACC in Nino3

Ensemble forecast system performanceEnsemble forecast system performanceEnsemble forecast system performanceEnsemble forecast system performance