TOPAZ report L. Bertino, F. Counillon, P. Sakov, E. Simon, G. Zangana, MQ. Fang Mohn-Sverdrup Center/NERSC GODAE Ocean View ST, Toulouse, June 2009

TOPAZ System overview System description Validation / metrics Plans

Uncertainty estimates Uncertainty estimates Hindcast studies Atmospheric Data Atmospheric Data Satellite Data SLA, SST, Ice, In Situ Data Analyze the ocean circulation, sea-ice and biogeochemistry. Provide real-time forecasts to the general public and industrial users EnKF Data assimilation system User-targeted ocean forecasting User-targeted ocean forecasting Ocean Primary production Ocean Primary production Gulf of Mexico model Atlantic and Arctic model Sea-Ice model Eco- system model

The TOPAZ model system  TOPAZ3: Atlantic and Arctic  HYCOM + EVP sea-ice model  km horizontal resolution  22 hybrid layers  EnKF  100 members  Observations  Sea Level Anomalies (CLS)  Sea Surface Temperatures (NOAA)  Sea Ice Concentr. (AMSR, NSIDC)  Sea ice drift (CERSAT) 4D-EnKF  Argo T/S profiles (Coriolis)  Runs weekly, 10 days forecasts  ECMWF forcing

EnKF Correlations, SST 3 rd Jan th Nov 2006

Ice concentration multivariate update summer [ K.A. Lisæter et al. 2003] Impact on temperature Impact on salinity

The HYCOM model  3D numerical ocean model  Hybrid Coordinate Ocean model, HYCOM (U. Miami)  Hybrid coordinate  Isopycnal in the interior  Z-coordinate at the surface  Coupled  Sea-ice model (EVP)  Ecosystem models  NORWECOM (IMR, UiB)  Interface to EnKF  Analysis in model space  u,v, t, s, dp (layer thickness)  Connection to N-MICOM in the Bergen Climate Model

Nesting  Arbitrary resolution and orientation of the nested grids  6-hours frequency of nesting conditions  Inclusion of tides  Only one-way nesting  A few regions (none in real-time at present)  Gulf of Mexico (with DA, no tides)  Barents Sea (tides, no DA)  Norwegian Sea (tides, no DA)  Fram Strait (tides, no DA)

Application: Iceberg forecasting  Iceberg modelling  PhD of I. Keghouche  Iceberg model forced by a 5 km Barents Sea HYCOM model  Nested into the TOPAZ system  Not yet in real-time  Ensemble of icebergs:  Variable size, Ca, Co Keghouche et al., JAOT, In press

Example of products icebergs simulations  Random simulations using calving rates for major glaciers, 1 year I. Keghouche

Data service / Transition to operations / computers  NERSC / met.no  March 2008: TOPAZ3 exploited in met.no’s operational suite.  Developments at NERSC, still run as a backup  Data service also duplicated  Updated on Thursd. / Friday  Best guess = ensemble mean  Forecast = 1 member  NERSC:   Met.no:  (MERSEA…)  Computing resources  Ensemble forecast 2000 CPU h / week  Analysis  24 CPU h / week  Met.: IBM (1000 CPUs)  NERSC: Cray XT4 (5500 CPUs)  Products on FTP  BC to ourselves (Fram Strait, Barents Sea)  BC to DMI (Nares Straits)  Surface currents to ECMWF’s wave model.

Wave modelling at ECMWF (J. Bidlot, ECMWF)  TOPAZ surface currents in ECMWF wave model  Hs: Small improvement of scatter index  Larger improvement for peak periods  But biases are slightly more negative  ECMWF has requested access to TOPAZ data for operations -TOPAZ - control

TOPAZ System overview System description Validation / metrics Plans

Issues with ensemble systems  What is the “best guess”?  Ensemble mean  Minimum least square error  Most suitable for “Accuracy” metrics  But not “Consistency”:  Smoothes the EKE, MLD…  Ensemble SD are computed but not served so far  Doubles the NetCDF file storage  What is the forecast?  So far in TOPAZ = 1 member (for simplicity)  Natural to initialize an ensemble forecast ForecastAnalysis Observations Member1 Member2 …… Member99 Member10 0

Arctic Metrics Documentation in MERSEA WP05 report by Bertino, Lisæter, Garric (2005)

TOPAZ3 Climatology Too deep mixed layer in the Sub-Arctic Gyre Validation of MLD against clim.

Bear Island opening, Temperature TOPAZ2TOPAZ3IMR obs Apr 2007 Jun 2007 Aug 2007

Online comparison to Argo profiles

Water Transports Denmark Strait Fram Strait Barents Sea opening

Sea ice Transports, 2007 Fram Strait Spitzbergen - Franz Joseph Land

Sea-ice edge Assimilation + 6 days  Ice concentration from model in color, SSMI 15% ice contour in black. Ice drift is overlaid.  Good overall correspondence between model and data  Visual comparison allows identification of problematic regions  South of Svalbard (Bear Island) model ice edge too far to the north  East Greenland, too little ice South of Denmark Straits  Issues related to model physics  Ice-ocean momentum exchange  Ice models neglect physics which may be important on small scales  Fast ice  MIZ

Ice Forecast skills by region – 6 months average see N. Alaska Barents Sea Bering Strait Central Arctic Greenland Sea Kara Sea

Barents Barents TOPAZ2 systemTOPAZ3 system Nordic Nordic LabradorLabrador SSH residuals by region

MERSEA Arctic sections updated  Blue: MERSEA Class2 sections  Red: Sections from IMR  Problem: need to reprocess all past products.  Should the metrics upgrades be synchronized to system upgrades?

TOPAZ System overview System description Validation / Metrics Plans

TOPAZ4 HYCOM upgrade (v2.2.12)  Features used for TOPAZ4  Hybrid grid generator:  3 different vertical interpolation methods (PCM, PLM, PPM, WENO )  Improved treatment of rivers  Mass fluxes  More stable in shallow waters (Morel et al. 2008)

Other upgrades in TOPAZ4 TESTED  Vertical resolution  28 layers instead of 22  Thicker z-levels for deep mixed layers  Sea ice model (EVP)  Advection scheme (WENO)  Snow distribution  Tuning of P* (ice strength)  River fluxes from hydrologic model (TRIP), Oki and Sud (1998)  Bering Strait fluxes from Pacific  Flux: 0.8 Sv at climatology T/S  Sea-level altimeters tracks ONGOING  Forcing fields: ERA-Interim (to be tested)  Assimilation of ocean colour in HYCOM-NORWECOM  MIZ sea-ice rheology (TOTAL) PLANNED  Ferrybox data (Svalbard)  Gliders (FFI-met.no)  Rio05 MDT  HR SST (Ostia/Odyssea)  New satellites  GOCE, SMOS, CryoSAT

Vertical resolution maximum z-levels Thin z-levelsThick z-levels

Two effects: Snow increases the albedo Isolates the ice Probabilistic snow distribution: Snow module V. Vionnet Ice areaIce volume Leads to more ice Pacific ice not in TOPAZ

River forcing - TRIP

Effect of the HYCOM upgrade Weekly SST in Dec. 1999, free run TOPAZ3TOPAZ4 AVHRR L4 SST

Effect of the HYCOM upgrade Weekly SSS in Dec. 1999, free run TOPAZ3TOPAZ4 Next target: N-MICOM (BCM) Incremental remapping

TOPAZ4-TOPAZ3 Transport estimates TOPAZ3TOPAZ4Observed value Positive is Fram Straits (Net) 0.69 Sv2.0 Sv~2 SvSouthwards Bear Island (Net) 0.85 Sv2.19 Sv SvEastwards Nordic Sea (Northwards) (Iceland-Færoe-Shetland- Scotland) 7.68 Sv7.76 Sv7-8 SvNorthwards Improvement of the “critically important fluxes”

Forecast plans  Met.no has switched TOPAZ3 to daily forecasts  Updated fluxes  But not yet daily updates…  Arctic Intercomparison led by NERSC  Involve met.no, NIERSC (ocean, sea-ice)  TOPAZ4 in real-time by Oct  Run 10-members 10-days forecasts  Out of the 100 members EnKF ensemble

Reanalysis plan  MyOcean:  20 years reanalysis with TOPAZ4  HYCOM 2.2, same horizontal resolution, 28 hybrid layers  Assimilate delayed mode data (hydrographic, ice)  Along-track altimeter data  Schedule  Starting with  Then years  Delivery by Oct. 2010

Assimilation of Ocean Color in HYCOM-NORWECOM Data: Satellite Ocean Color (SeaWIFS) Coupled Model: HYCOM-NORWECOM (7 compartments) Problems: Coupled 3-dimensional physical-biological model. High-dimension. Non-Gaussian variables. Perspectives: Environment monitoring. Fisheries. Methodological developments

Gaussian anamorphosis with the EnKF Simon & Bertino (OSD, 2009) Anamorphosis: transformation of the distributions to Gaussian (Bertino et al. 2003) Twin experiments (surface chlorophyll-a synthetic observations) Surface CHL a RMS error EnKF Cut-off of neg. values Gaussian Anamorphosis EnKF

Outreach (1)  Dynamics visualization  OPeNDAP client DAPPER/DCHART   Inclusion into the Norwegian weather website  University of Bergen:  Operational Oceanography courses  Hands on experience to OPeNDAP in Matlab  Arctic ROOS  Secretariat = S. Sandven (NERSC)   Has several members  Presents obs and model  IPY – DAMOCLES  Acoustic tomography in the Fram Strait  Monitor heat fluxes in / out of the Arctic

Data service: OPEnDAP/THREDDS Web client: DCHART/DAPPER G. Zangana

Acoustic Tomography DAMOCLES project [ H. Sagen, NERSC ]  Fram Strait, 25 th July 2007  Average sound speed between source and receiver  Uncertainty taken from the TOPAZ ensemble forecast  100 members  Sept. 2008, deployment successful  More validation to come...

Outreach (2)  China  Nansen-Zhu Center at IAP in Beijing  Jiang Zhu’s group  Shared HYCOM, EnKF/EnOI  Collaboration with NMEFC (operational)  DRAGONNESS project (EU, support action)  India  Nansen Center in Kochi  Shared HYCOM  Collaboration with INCOIS, Hyderabad (operational)  Shared HYCOM, EnOI  South Africa  PhD B. Backeberg, Uni. Cape Town  Shared HYCOM

Work has been done: Nested model around China Seas AVHRR, º×0.25º HYCOM, , 0.1º×0.1º M.Q. Fang (Uni. Qingdao) Comparison between the AVHRR OI sst (from NOAA) and the HYCOM sst

Near Future Research Plan: HYCOM, , 0.1º×0.1º Further Nesting to some local areas for specific studies, with data assimilation/validation HYCOM, SST , 1/18º-1/32º

Publications mostly MERSEA Oc. Sci. Special issue  Samuelsen A., L. Bertino, and C. Hansen The 2007 North Atlantic spring bloom in operational analysis from the TOPAZ system Ocean Sci. Discuss., 6, , 2009  Backeberg B. C., L. Bertino, and J. A. Johannessen Evaluating two numerical advection schemes in HYCOM for eddy-resolving modelling of the Agulhas Current Ocean Sci. Discuss., 6, , 2009  Simon E. and L. Bertino Application of the Gaussian anamorphosis to assimilation in a 3-D coupled physical-ecosystem model of the North Atlantic with the EnKF: a twin experiment Ocean Sci. Discuss., 6, , 2009  Counillon F., P. Sakov, and L. Bertino Application of a hybrid EnKF-OI to ocean forecasting Ocean Sci. Discuss., 6, , 2009  Keghouche, I., L. Bertino, K.A. Lisæter (2009) Parameterization of an iceberg model in the Barents Sea. JAOT, in press.