Developments within FOAM Adrian Hines Dave Storkey Rosa

Developments within FOAM Adrian Hines, Dave Storkey, Rosa Barciela, John Stark, Matt Martin IGST, 16 Nov 2005 www. ncof. gov. uk

Present systems & recent developments Open ocean forecasting: FOAM – Forecasting Ocean Assimilation Model adrian. hines@metoffice. gov. uk www. ncof. gov. uk

Overview of the FOAM system FOAM = Forecasting Ocean Assimilation Model T+24 forecast used in QC Obs QC & processing Real-time data • • NWP 6 hourly fluxes Analysis Hindcast system Operational system Forecast to T+120 Automatic verification Product dissemination Operational real-time deep-ocean forecasting system Daily analyses and forecasts out to 5 days Hindcast capability (back to 1997) www. ncof. gov. uk Relocatable high resolution nested model capability

Model & Operational system • Ocean model – Z-level, primitive equation model – Same code as used in Hadley Centre climate models – Rigid lid – Kraus-Turner + K-profile vertical mixing – Simple advective sea-ice model – Flow Relaxation Scheme at open boundaries for nested models • Operational system – Three suites of nested models: • QO 00: Global, North Atlantic and Mediterranean, starts at 05: 00 Z • QN 00: Indian Ocean, starts at 00: 30 Z • QV 00: Antarctic, starts at 01: 45 Z – – Run daily on 7 NEC SX 6 processors Responsibility of operational teams; 7 -day operator support Boundary data provided to operational Shelf Seas model Automated verification system running at T+7 days www. ncof. gov. uk

Operational configurations 1º Global 36 km (1/3º) North Atlantic and Arctic 12 km (1/9º) North Atlantic 36 km (1/3º) Indian Ocean 12 km (1/9º) Mediterranean 27 km (1/4º) Antarctic 12 km (1/9º) Arabian Sea • All configurations run daily in the operational suite • Output available on HORACE www. ncof. gov. uk

Data assimilation • • Data assimilation is key to initialising the models for effective forecasting All FOAM configurations assimilate a range of data: Argo float distribution at end of March – Temperature and salinity profiles including Argo floats – Satellite altimeter Sea Surface Height – In situ and satellite Sea Surface Temperature • New generation of satellite SST products being tested – Sea-ice concentration Improved satellite SST data Current Sat. SST data: c. 3000 obs daily New data: Atlantic > 2. 5 million obs daily www. ncof. gov. uk

Partial Cell Bathymetries • Improved topographic steering of currents Model bathymetry Model streamfunction Full cells Partial cells dave. storkey@metoffice. gov. uk www. ncof. gov. uk

Dependence of forecast bias on advection scheme Annual mean of analysis temperature increments along 65ºW 3 D QUICK 4 th order + biharmonic GM dave. storkey@metoffice. gov. uk www. ncof. gov. uk

Assessments of Mixed Layer Global mean mixed layer depth error • Careful assessment of mixed layer schemes using Argo and OWS Papa data • More reliable diagnostic of mixed layer developed Old MLD david. acreman@metoffice. gov. uk New MLD www. ncof. gov. uk

Ecosystem, air-sea CO 2 fluxes and water clarity • Hadley Centre Ocean Carbon Cycle model (Had. OCC) has been coupled with the FOAM system • FOAM-Had. OCC running at 1º, 1/3º and 1/9º resolution • Assessment of initial year-long integrations underway • Diagnostics of p. CO 2 and water clarity • Ocean colour data assimilation scheme (developed by NOCS) implemented and testing commenced rosa. barciela@metoffice. gov. uk Chlorophyll for mid -March 2000 1º FOAMHad. OCC Sea. WIFS data www. ncof. gov. uk

Sea-ice data assimilation • A system for assimilating seaice concentration data into FOAM has been developed with funding from ESA – Assimilation improves representation of the ice, especially the ice edge • A scheme for the assimilation of ice velocity has also been developed which adapts the stresses on the ice to match observations www. ncof. gov. uk john. stark@metoffice. gov. uk

Assimilation of Altimeter Data Identical twin experiments used to explore poor performance Bottom pressure errors are up to 30% of surface errors Old MLD Surface pressure difference New MLD Bottom pressure difference matthew. martin@metoffice. gov. uk www. ncof. gov. uk