1. ECMWF NEMOVAR update, NEMOVAR meeting 16-17 Jan 2012 1 ECMWF update 2011-2: NEMOVAR ORA-S4 (Ocean Re-Analysis System 4) implemented operationally  Based on NEMO/NEMOVAR ORCA1 configuration  It provides initial conditions for EPS and Seasonal. Value for climate: Ocean Re-analysis, initialization of decadal forecasts by EC-EARTH Validation of ORA-S4  Can we learn any lessons? Is there room for improvement?  What is the value of the assimilation? [ OSES, comparison with CONTROL]  Identifiy and Assess robustness of climate signals oOcean Heat Content, Thermocline trends, MOC variability  The heat budget in NEMOVAR. Dissemination of Results  Web Pages for ORAS4. Almost there http://www.ecmwf.int/products/forecasts/d/charts/oras4/reanalysis/http://www.ecmwf.int/products/forecasts/d/charts/oras4/reanalysis/  Report (tech-memo): description and summary of performance. Ongoing  Maybe some papers. Abstract to WCRP conference on reanalysis  Data in community servers (EasyInit). To do  Several data requests already. ”

2. ECMWF NEMOVAR update, NEMOVAR meeting 16-17 Jan 2012 2 ORAS4: 5 ens members 195709 to present Other information Bias correction scheme estimated from Argo Period. Delayed reanalysis suite and real time suite

3. ECMWF NEMOVAR update, NEMOVAR meeting 16-17 Jan 2012 3 Assessment of ORAS4 Fit to assimilated data: Improvement. Importance of bias correction. Comparison with independent data: Velocity: Improvement in general, but not always. Success stories: Eastern Pacific, Atlantic No so successful: Central/West Pacific, Upper Indian Ocean. MOC: Degradation of Florida Strait current. Time variability Comparison with SL altimeter: Improvement in general. Problems with the Mediterranean Outflow?? TO BE DIAGNOSED farther Comparison with OSCAR currents: Improvement Impact on Seasonal Forecasts: Improvement Aspects that need improvement Covariance estimation: spatial and time dependence. Assim near coast (MOC) T/S balance (Mediterranean Outflow) Altimeter assim (Better tuning of Unbal eta, include Sunbal) More diagnostic tools required: Balanced and unbalanced increments.

4. ECMWF NEMOVAR update, NEMOVAR meeting 16-17 Jan 2012 4 Fit to Observations Assim shows better fit than Control Error decreases with time in both, indicative of improvement of forcing fluxes. Bias is more stable in Assim. Temperature Salinity

5. ECMWF NEMOVAR update, NEMOVAR meeting 16-17 Jan 2012 5 Fit to ADCP Velocity Observations PIRATA (Atlantic) Obs ORAS4 CNTL TAO (Pacific)

6. ECMWF NEMOVAR update, NEMOVAR meeting 16-17 Jan 2012 6 More on Ocean currents: Time and variability Central Pac: -ve impactEastern Pac: +ve impact

7. ECMWF NEMOVAR update, NEMOVAR meeting 16-17 Jan 2012 7 Correlation with Altimeter General Improvement Little impact of altimeter at high latitudes Very little weight to the unbalance component Decrease of correlation West Iberian Under study. Possible problem How to improve further the assimilation of altimeter? Include effect of unbalance salinity Better definition of mixed layer depth (rho=0.01 criteria underestimate MLD) MDT from observations (Dan’s work) Better tuning of balance/unbalance covariances.

8. ECMWF NEMOVAR update, NEMOVAR meeting 16-17 Jan 2012 8 Problems with the Mediterranean Outflow There is a salinity minimun at around 2500 in ORAS4. Is it real? Comparison with obs, but then obs can be wrong Even if obs are right, may model can not sustain it? If not real, why? Is it related to the degradation of the correlation with altimeter? We are looking slowly looking into it. Has anybody seen similar behaviour?

9. ECMWF NEMOVAR update, NEMOVAR meeting 16-17 Jan 2012 9 Med Outflow problem and Assimilation We should look at the balanced/unbalanced separation of increments

10. ECMWF NEMOVAR update, NEMOVAR meeting 16-17 Jan 2012 10 Plans Transition to NEMO/NEMOVAR 3.4 (discussion tomorrow) New Ocean configurations: ORCA025_L75 as well as ORCA1_L75 Tuning of background/obs errors Revise analysis cycle? LIM2 sea-ice model Assimilation of sea-ice in NEMOVAR? Any relevant data sets for the obs-operator and diagnostics? MyOcean2 ocean re-analysis: 2 years starting ~ April 2012 ORCA025+NEMOVAR+Up-to-date datasets (OSTIA, SL ECV,MDT…) Hopefully other improvements. CERA project: Weakly coupled DA using for reanalysis applications. ESA funded. 2 years x 2 positions. Starting ~ April 2012 4 Stages: CERA-S, CERA-O, CERA-A, CERA

11. ECMWF NEMOVAR update, NEMOVAR meeting 16-17 Jan 2012 11 Fit to Observations