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Salinity impacts in the GMAO ocean data assimilation Chaojiao Sun

Salinity impacts in the GMAO ocean data assimilation Chaojiao Sun. Experiments Assimilation method Forcing GFDL 3D-VAR, Assimilating T only ODASI ODASI-T OI, Assimilating T only ODASI ODASI-TS OI, assimilating T and S ODASI GMAO-T OI, Assimilating T only GMAO

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Salinity impacts in the GMAO ocean data assimilation Chaojiao Sun

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  1. Salinity impacts in the GMAO ocean data assimilationChaojiao Sun ExperimentsAssimilation methodForcing GFDL 3D-VAR, Assimilating T onlyODASI ODASI-T OI, Assimilating T only ODASI ODASI-TS OI, assimilating T and S ODASI GMAO-TOI, Assimilating T only GMAO GMAO-TSOI, Assimilating T and S GMAO GMAO-CTL No assimilation GMAO Two GMAO schemes treat salinity differently: T – scheme: T assimilation only, S updates based on model T-S relationship (Troccoli and Haines, 1999) TS – scheme: T and S assimilation (S comes from ARGO when available, otherwise from Levitus climatology) Contributors: Michele Rienecker, Christian Keppenne, Jossy Jacob, Anna Borovikov (GMAO) Tony Rosati, Andrew Wittenburg, Matthew Harrison (GFDL)

  2. GFDL analysis GMAO-T ODASI-T T at 140°W (1993-2002) GMAO-TS ODASI-TS GMAO-CTL TAO OBS

  3. GFDL analysis GMAO-T ODASI-T U at 140°W (1993-2002) GMAO-TS ODASI-TS GMAO-CTL TAO OBS

  4. 1993-2002 average of U at 140°W Chaojiao Sun JCSDA Workshop April 20, 2005

  5. (Johnson et al., 2002) Chaojiao Sun JCSDA Workshop April 20, 2005

  6. 1993-1998 Average (Ricci et al., 2005) 1993-2002 Average

  7. TAO servicing cruise tracks (meridional sections) (Johnson et al., 2002) Chaojiao Sun JCSDA Workshop April 20, 2005

  8. RMS T RMS T N. Niño 4 (0°-5°N) N. Niño 3 (0°-5°N) RMS S RMS S RMS U RMS U

  9. RMS T RMS T S. Niño 4 (5°S-0°) S. Niño 3 (5°S-0°) RMS S RMS S RMS U RMS U

  10. ECCO-GODAE project (1st year) • Testing and porting MOM4 into the GMAO ocean model suite, and begin simulation • Porting MOM4 in GMAO setting to JPL • Compare MOM4 results and data, including model error calibration • Derivation of Kalman filter and smoother of MOM4 in GMAO setting

  11. Conclusions: • TS scheme is effective in • (1) correcting salinity bias in the model • (2) constraining zonal current • 1. Subsurface current structure – independent validation • - GMAO compared well with TAO ADCPs (zonal structure on the EQ); GFDL compared well with Johnson’s data (meridional structure) • - sensitive to treatment of salinity – “TS” appears to be effective • “TS” significantly improves subsurface salinity structure both zonally and meridionally, especially below the EUC core on the equator and in the northern Niñ0 3 & 4 regions; model bias is present in “T” scheme. • To effectively reduce salinity bias in the top 100-150m, satellite/in-situsalinityobservations need to be assimilated • Ongoing work: treat surface salinity properly in “TS” • investigate the impact of ARGO assimilation Chaojiao Sun JCSDA Workshop April 20, 2005

  12. The End Chaojiao Sun JCSDA Workshop April 20, 2005

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