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© Crown copyright Met Office
IGST XIIIUK national report
Matt Martin
Silver Spring, USA, 2 - 4 June 2008
© Crown copyright Met Office
Contents
• Update on NCOF
• Progress with NEMO ocean model framework
• Data assimilation progress and plans
• Ecosystems
• OSTIA
• Shelf-seas
• Data delivery
© Crown copyright Met Office
Update on NCOF
• NCOF was launched in March 2005
• Partners are the Met Office and the NERC marine research institutes
• POL, NOCS, ESSC, PML
• CEFAS are Observers, with a view to joining
• The Consortium Agreement is nearing completion
• The scope of NCOF is being broadened to include a wider range of timescales and to more explicitly include observational programmes.
• NCOF Workshops
• Annual gatherings
• NCOF website: http://www.ncof.co.uk
© Crown copyright Met Office
Progress with NEMOOverview
• NEMO is the Nucleus for European Modelling of the Ocean
• All Met Office ocean modelling activities will use NEMO, including shelf-seas, FOAM, seasonal forecasting and climate prediction.
• NEMO Consortium Agreement has been signed
• NEMO Systems Team
• Core of team at CNRS (Paris), but consortium agreement commits resources from NOCS (Southampton) and Met Office (Exeter)
• NEMO Users
• Includes the open ocean, shelf seas, seasonal forecasting and climate prediction communities
• Intention to use NEMO as the primary open ocean modelling tool across all communities
© Crown copyright Met Office
• FOAM model component is being transitioned to use NEMO.
• For the My Ocean project, responsibility for global and North Atlantic coverage is led by Mercator with FOAM providing backup.
• Model configurations are shared with different choices for surface forcing, parameter settings and assimilation.
• Currently using LIM2 ice model. Plan to switch to CICE.
• The initial system has been run in hindcast mode and is being run in the trial operational suite.
• First ORCA025 hindcast run from 1st April 2005 – April 2007:
• Initial conditions produced by running model only for 3 months (starting from operational FOAM 1˚ restart file on 1st Oct 2004) then with assimilation for 3 months.
• Forced by 6-hourly Met Office NWP surface fluxes.
• With LIM2 ice model.
Progress with NEMO:FOAM
© Crown copyright Met Office
Global ¼˚ (ORCA025)
grid, bathymetry and river outflow climatology provided by Mercator
N. Atlantic 1/12˚
Indian Ocean 1/12˚
Med. 1/12˚
All configurations have 50 levels with 1m resolution near surface.
Progress with NEMO:FOAM configurations
© Crown copyright Met Office
• Initial results of verification of hindcast of ¼˚ NEMO.
• Comparison of model background with observations (before they’ve been assimilated).
• Averaged errors for Jan 2006 (after 10 months).
Temperature Salinity
Temperature overall RMS error 0.77K
© Crown copyright Met Office
Progress with NEMO:Comparison of trial operational NEMO with OSTIA SST
FOAM-NEMO SST on 14th May 2008 OSTIA SST analysis on 14th May 2008
© Crown copyright Met Office
• The existing operational FOAM system and the new global FOAM-NEMO system will be used as part of the GODAE intercomparison project.
• The new FOAM-NEMO system will be used to run data withholding experiments for the GODAE OSE project.
• Future plans are to fully implement the global and regional FOAM-NEMO configurations operationally in 2008. These will take over from the existing FOAM system at that stage.
• A number of hindcasts with the models will be run and assessed.
• Future model developments will aim to improve the results of the hindcasts.
• Transition the system to the new supercomputer in 2009.
Progress with NEMO:FOAM model plans
© Crown copyright Met Office
1960 1970 1980 1990 2000
year
Dra
ke p
assa
ge tr
ansp
ort (
Sv)
Drake Passage transport• High resolution hindcasts (with ecosytem models included) eg global 1/4 degree
• NEMO model has now completed 1958-2001, then started again from the 2001 state but with fluxes from 1958 to allow the ocean to properly spin-up
• Proposal to compare NOCS hindcast runs (without data assimilation) with similar runs undertaken by ESSC which do include assimilation - to assess the effect of the assimilation.
Progress with NEMO:Recent work at NOCS
© Crown copyright Met Office
Global Ocean Modelling with Adaptive Unstructured Grid Methods
Aim: produce a global circulation model which fully utilises three-dimensional adaptive mesh technology – based on ICOM
(FInite-eLement Adaptive grid Modelling of Ecosystems and Nutrient Transport)
Aim: Embed an ecosystem model into a newly developed, non-hydrostatic, finite element, adaptive grid, physical ocean model
Progress with NEMO: Long-term modelling
plans at NOCS
© Crown copyright Met Office
ESSC: Model/Synthesis details
• Completed Synthesis experiments (Hydrography only assimilation)
• Global 1° resolution (1958-2004) 46 years
• Global 1/4° resolution (1987-2004) 18 years
• NEMO modelling framework
• Collaboration with DRAKKAR consortium who have run the global 1/4° resolution model only for 46 years.
• Bulk forcing (DFS3) from ERA40/ECMWF operational analyses & CORE (ISCCP)
• Data assimilation scheme is based on an isothermal analysis (changes depth of isotherms and salinity on isotherms).
• Now extending runs
• 2005-2007 using ECMWF Operational forcing
• 1989-1998-present will be done using ERA-Interim (4DVar atmosphere with better fluxes)
© Crown copyright Met Office
ESSC: Biases in the 2004 mean state
ORCA025-G70Simulation only
ORCA025-R07Assimilation
ClimatologyWOA05
Average 300-1000m
© Crown copyright Met Office
Transports (Black Simul., Green Synth.)
© Crown copyright Met Office
• All FOAM configurations assimilate a range of data using an Optimal Interpolation type method. Data types include:
• Temperature and salinity profiles including Argo floats (also XBTs, CDTs, buoys,…)
• Satellite altimeter Sea Surface Height
• In situ and satellite Sea Surface Temperature
• Sea-ice concentration
Argo float distribution
Satellite SST data: 50km product (from NESDIS)
Argo Network as of April 2008
Altimeter SSH data for 10 days
Processed for 1/9º North
Atlantic model
Data assimilation: Overview of FOAM scheme
© Crown copyright Met Office
• Overall data assimilation methodology the same as current operational FOAM. Includes assimilation of T and S profile data, satellite altimeter SLA data, in situ and satellite SST data, and sea-ice concentration data.
• Improvements include:
• First-guess-at-appropriate-time (FGAT) which provides more accurate calculation of the model counterpart of the observation.
• Improved sea ice assimilation uses OSI-SAF sea ice concentration data and uses the OI scheme as do all the other data types.
Data assimilation in FOAM:Implementation in NEMO
Observed sea-ice concentration 1st Feb 2006
Background sea-ice concentration 1st Feb 2006
© Crown copyright Met Office
To be included in next operational change and next hindcast run:
• New error covariances being generated for ORCA025 using two techniques – using (o-b) and NMC method - using data from the 2 year hindcast.
• Altimeter bias correction in order to account for inconsistencies between the mean dynamic topography (MDT) and the model.
• Pressure correction, to account for model biases in the tropics.
• Scheme to include correlation scales which vary depending on the horizontal gradients of potential vorticity in the background field.
• Assimilation of GHRSST data (high-resolution SST), including satellite SST bias correction, as is used in OSTIA.
Data assimilation in FOAM:Recent developments in FOAM-NEMO
© Crown copyright Met Office
STDBIAS
• No bias correction (black) compared to bias correction (red)• After only 1 month SSH RMS error 10 cm rather than 12 cm• Minor improvements in T and S
RMS
mean
Data assimilation in FOAM: Altimeter bias correction scheme
© Crown copyright Met Office
• Assimilate various high resolution SST data sets from GHRSST (L2p data)
• Include bias correction scheme used by OSTIA
• AATSR and in situ data treated as reference data set in bias correction
1 day of satellite data – 8th April 2008
Data assimilation in FOAM: Assimilation of GHRSST data
© Crown copyright Met Office
• A review of the various assimilation schemes available for use in operational ocean forecasting has been carried out.
• It was decided to begin implementing a variational scheme, NEMOVAR. Developed at CERFACS and ECMWF.
• Initial implementation in FOAM will be 3DVar with the capability to move to 4DVar in the future.
• Developments will be made to implement anisotropic error covariance representation within NEMOVAR.
• Investigate impact of a different change of variable to, for instance, density and spiciness.
Data assimilation in FOAM: Plans
© Crown copyright Met Office
Ecosystem modellingFOAM-HadOCC overview
• FOAM-HadOCC running at 1º, 1/3º and 1/9º resolution
• Assessment of initial year-long integrations underway
• Ocean colour data assimilation scheme (developed by NOCS) implemented and testing started
Schematic of HadOCC
• Development of open ocean water clarity capability
• Hadley Centre Ocean Carbon Cycle model (HadOCC) has been coupled with the FOAM system
• NPZD ecosystem model
© Crown copyright Met Office
Daily mean RMS errors in the North Atlantic Air-sea exchange of CO2
significantly improved after assimilating ocean colour data
Phytoplankton (mmol N/m3) Zooplankton (mmol N/m3)
Control - truth Assimilation - truthAssimilation - truth
Total DIC (mmol C/m3)
Free run
BDA run
Detritus (mmol N/m3) Nutrients (mmol N/m3)
Ecosystem modelling:Identical twin experiments
Control - truth
Assimilation - truth
© Crown copyright Met Office
Global average RMS (solid lines) and mean (dashed lines) errors compared to satellite chlorophyll data.
Green: no DA Black: only physical DA Red: physical and biological DA
The scheme appears to be effective at correcting chlorophyll Validation of other biological variables against independent data (CAVASOO)
has begun
Ecosystem modelling:Real world experiments
© Crown copyright Met Office
Ecosystem modelling:Plans
• The key next steps are:
• further quantitative validation of initial FOAM-HadOCC integrations.
• further refinement of biological assimilation scheme.
• parameter tuning (required to improve performance).
• 10-year re-analysis of FOAM-HadOCC with ocean colour and physical assimilation (1º global).
• on-line coupling to NEMO.
© Crown copyright Met Office
NanoPhyto
Si
Diatoms
Fe N
MesoZoo
MicroZoo
Slowdetritus
Fast particle flux
Model of Ecosystem Dynamics, nutrientUtilisation and SequestrAtion
Chlorophyll (mg m-3), 15 May
MEDUSA in ¼º NEMO
© Crown copyright Met Office
Shelf seas forecasting at the Met Office
6km MRCS Model
1nm Irish Sea
Model
12km Atlantic
Margin Model
• NEMO will form basis for our North-west Shelf system. Boundary conditions will come from the 1/12 degree N Atlantic FOAM-NEMO model.
• Various new schemes implemented in NEMO by different European groups to enable running in the shelf-seas
• POLCOMS and NEMO run on AMM domain, same horizontal + vertical resolution.
• 1-year tides-only experiments forcing with 15 tidal components at lateral boundaries.
• Validated against tide gauge and buoy data, plus Topex data.
• Each model run with native TKE scheme and also with k-ε model (Canuto et al 2001) within GOTM framework.
© Crown copyright Met Office
Validation against satellite data (TPXO): amplitude errors (m)
POLCOMS NEMO
© Crown copyright Met Office
OSTIA: Operational SST & Sea Ice Analysis
• Daily 1/20° (~5.6km) global SST analysis.
• Analysis of the ‘foundation’ SST [pre-dawn or below the diurnal warm layer].
• Blend of data sources, using satellite (microwave & IR) and in situ data.
• Using many GHRSST data products.
• Almost all Medspiration products.
• Now running daily, operationally.
• Using a scheme based on the FOAM assimilation scheme, with persistence based background.
• Uses sea ice analysis performed by EUMETSAT OSI-SAF (met.no / DMI).
Sample analysis for 19 Apr 2007
© Crown copyright Met Office
• OSTIA improved the RMS and bias in the NWP forecasts during the trial period (August 2007).
RMS Error
Mean Error Reduced Bias at low levels
Pre
ssur
e Le
vel
© Crown copyright Met Office
• Direct links to UK Royal Navy forecasters.
• For commercial use, data is available from the Met Office’s Data and Products Distribution System (DPDS) at http://www.metoffice.gov.uk/research/ncof/foam/dpds.html
• Data available for research use from Live Access Server at http://www.nerc-essc.ac.uk/godiva/
• A new prototype data server has been developed and is undergoing testing. One new advance with this server is the ability to visualise NCOF data using Google Earth.(http://behemoth.nerc-essc.ac.uk/ncWMS/godiva2.html)
Products distribution:Overview
© Crown copyright Met Office
© Crown copyright Met Office
• A service desk will be operated at the Met Office for all European Marine Core Services:
• Data policy still to be defined but is likely to be freely available to all users and free of charge
• Users will be able to access data via the service desk using service level agreements (SLAs)
• Data will be supplied from production centres in Europe
• Present plan is for data to be available via sftp
• OpenDAP technologies will be introduced at a later date
• On-line catalogues will be available to search for products
Products distribution:Future system in My Ocean
© Crown copyright Met Office
Phase errors for M2 component (degrees)
POLCOMS-GOTM NEMO-GOTM
© Crown copyright Met Office
• Observation Operator (also in NEMOVar) allows
• Isotherm / Isopycnal depths
• Salinity / Spiceness on Isotherm / Isopycnal surfaces
• For isotherms:
• Given T, S -> Calculate Z(T), S(T) for model and observations
• Za(T) = Zb(T) + ΔZ(T) or Ta(z) = Tb(z) + ΔT(z)
• Sbal(z), such that Sa(Ta)=Sb(Ta)
• Sa(T) = Sb(T) + ΔS(T)
• For isopycnals:
• Given T, S -> Calculate Z(ρ), π(ρ) for model and observations
• Z’(ρ) = Zb(ρ) + ΔZ(ρ)
• π’(ρ) = π b(ρ) + Δπ(ρ)
• Current Syntheses all use Isotherm analyses
ESSC: Isothermal/Isopycnal Assimilation
© Crown copyright Met Office
RMS Salinity Misfits : 1988-2004
ORCA1-R70ORCA1-R07-RA_t1ORCA025-R07-RA_t1
FULL – Global
STNA – Sub-trop. N. Atl.20N-45N, 80W-8W
SPNA – Subpolar N. Atl.45N-65N, 65W-5E
MDNA – Mid N. Atl.30N-45N, 35W-20W