1. ASTE (former NOSE): An Arctic subpolar gyre State Estimate (NSF-funded) Patrick Heimbach, An T. Nguyen, Ayan Chaudhuri, Gael Forget, Rui M. Ponte, and Carl Wunsch MIT & AER Estimating the Circulation and Climate of the Ocean http://ecco-group.org

2. Hurricane Sandy on Oct 28, 2012 …

3. Rationale Produce a regional eddy-permitting state estimate focused on: –Arctic ocean –North Atlantic, especially subpolar gyre Special emphasis on: –Arctic sea ice-ocean interactions –a dynamically consistent Arctic hydrography –understanding of the planned subpolar gyre mooring array (OSNAP) –Arctic-subarctic exchanges –Subpolar-subtropical exchanges

4. ECCO-Production v4 grid: LLC_90

5. ASTE grid: LLC_270

6. ASTE domain

7. ECCO v4 residual misfit to in-situ obs. Take open boundaries from globally optimized solution

8. Observations: collecting dedicated hydrography in the Nordic Seas

9. observationinstrumentproduct/sourceareaperioddT Mean dynamic topography (MDT) GRACE SM004-GRACE3 GRACE GGM02 EGM2008/DNSC07 CLS/GFZ (A.M. Rio) CSR/U. Texas (B. Tapley) N. Pavlis globaltime-meanmean Sea level anomaly (SLA) TOPEX/POSEIDON Jason-1/2 ERS-1/2, ENVISAT GFO NOAA/RADS & PO.DAAC 65 o N/S 82 o N/S 65 o N/S 1993 – 2002 2002 – 2011 1992 – 2011 2001 - 2008 daily bottom pressure EIGEN-GRACE05GFZ Potsdamglobal2002 – 2011weekly SST blended, AVHRR (O/I) TRMM/TMI AMSR-E (MODIS/Aqua) Reynolds & Smith GHRSST Global 40 o N/S Global 1992 - 2011 1998 - 2004 2001 - 2011 monthly daily SSS Various in-situWOA09 surfaceGlobalclimatologymonthly In-situ T, S (floats, sections,…) Argo, P-Alace XBT CTD SEaOS Ifremer D. Behringer (NCEP) various SMRU & BAS (UK) “global” “gobal” sections SO 1992 – 2011 2004 – 2010 daily Mooring arrays TOGA/TAO, Pirata Florida Straits PMEL/NOAA NOAA/AOML Tropics N. Atl. 1992 – 2011 daily Climatological T,S WOA09 OCCA WOA09 Forget, 2010 “global” 1950 - 2008 1950 - 2002 mean sea ice cover satellite brightness temp. (passive microwave) NSIDC-0079 (Bootstrap) NSIDC-0051 (NASA Team) Arctic, SO1992 - 2011daily Wind stress QuickSCAT NASA (Bourassa) SCOW (Risien & Chelton) global1999 – 2009 climatology daily monthly Tide gauge SSH Tide gaugesNBDC/NOAAsparse1992 - 2006monthly Flux constraints from ERA-Interim, JRA-25, NCEP, CORE-2 variances Variousglobal1992 - 20112-day to 14-day Balance constraints heat & freshwater (E-P-R)global1992 - 2011mean bathymetry Smith & Sandwell, ETOPO5global--

10. Atmospheric forcing uncertainties Chaudhuri et al., submitted 2012: A comparison of atmospheric re-analysis products for the Arctic Ocean and implications for uncertainties in air-sea fluxes

11. Sea ice model development Improved sea ice thermodynamics –now conserves properties –supposedly more stable adjoint –easier term-by-term budget new sea ice tracer capabilities –first use is simulation of sea ice age to enable split into first- year (FY) vs. multi-year (MY) sea ice (Pierre Rampal, now at Nansen Center, Bergen) implementation of Ice Thickness Distribution (ITD) scheme (Torge Martin, now at APL, UW) sea ice dynamics: JFNK solver (Martin Losch) see tomorrow’s session

12. Initial sample results from improved sea ice model: Simulation and observation of multi-year sea ice fraction Rampal et al., in preparation

13. Initial sample results from improved sea ice model: Simulation of the decline of multi-year sea ice fraction Rampal et al., in preparation

14. Outlook – see also An Nguyen’s talk on Thursday Next steps: –initial optimization of global parameters, especially in relation to forcing fields –switch from JRA25 to ERA-Interim? –test of adjoint system, especially sea ice thermodynamics –assessment of an “iter. 0” estimate –perform initial optimization Long-term outlook: –Establish feedback loop between global LLC90 (ECCO v4) and regional LLC270 (ASTE); –Put into global LLC270 context –Develop higher-resolution nestings from optimized solution