Intercomparisons Working Groupe activities

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Intercomparisons Working Groupe activities
Prepared by F. Hernandez K. Lisaeter, L. Bertino,
F. Davidson, M. Kamachi, G. Brassington, P. Oke,
A. Schiller, C. Maes, J. Cummings, E. Chassignet,
H. Hulburt, P. Hacker, J. Siddorn, M. Martin, S.
Dobricic, C. Regnier, L. Crosnier, N. Verbrugge,
M. Drévillon, J-M Lellouche

• Status of the intercomparison exercice
• Some exemples of diagnostics based on Class 1/2

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Status of the intercomparison exercice

• Methodology decided
• Compare operational/dedicated hindcast from
  Feb-March-April period.
• Consistency and quality assessment (not
  performance)
• Intercomparison based on Class 1 and Class 2
  metrics, and reference data
• Files shared on OpenDap/FTP, assessment performed
  by different teams on dedicated ocean basins
• Preliminary work performed
• Intercomparison plan endorsed
• Technical implementation documents (metrics
  definition) written and distributed

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The validation  philosophy 

• Basic principles. Defined for ocean hindcast and
  forecast (Le Provost 2002, MERSEA Strand 1)
• Consistency verifying that the system outputs
  are consistent with the current knowledge of the
  ocean circulation and climatologies
• Quality (or accuracy of the hindcast) quantifying
  the differences between the system best results
  (analysis) and the sea truth, as estimated from
  observations, preferably using independent
  observations (not assimilated).
• Performance (or accuracy of the forecast)
  quantifying the short term forecast capacity of
  each system, i.e. Answering the questions do we
  perform better than persistency? better than
  climatology?
• A complementary principal, to verify the interest
  for the customer (Pinardi and Tonani, 2005, MFS)
• Benefit end-user assessment of which quality
  level has to be reached before the product is
  useful for an application

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Metrics definition (MERSEA heritage)

• CLASS1 like Regular grid and few depth, daily
  averaged
• Comparison of the 2D model surface SST and SLA
  with
• -SST
• -SLA
• -SSM/I Ice concentration and drift for
  Arctic and Baltic areas
• Comparison of each model (T,S) with
  climatological (T,S, mixed layer depth) at
  several depth (0m, 100m, 500m, 1000m )?

• CLASS2 like High resolution vertical sections
  and moorings
• Comparison of the model sections with Climatology
  and WOCE/CLIVAR/OTHER/XBT
  hydrographic
  sections
• Comparison of the model SLA at tide gauge
  location, of the model (T,S,U,V) at fixed mooring
  locations

• CLASS3 like Physical quantities derived from
  model variables
• Comparison of the model volume transport with
  available observations (Florida cable
  measurments.)
• Assessment through integrated/derived quantities
  Meridional Overturning Circulation, Warm Water
  Heat Content etc.

• CLASS4 like Assessment of forecasting
  capabilities
• Comparison between climatology, forecast,
  hindcast, analysis and observations
• Comparison in 15x15degree boxes/dedicated boxes
  of each model with
• T/S CORIOLIS, SSM/I Sea Ice concentration, tide
  gauges
• SST High resolution ?
• SLA AVISO ?

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Class 2/3 MERSEA/GODAE GLOBAL METRICS Online
Systematic Diagnostics
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• Compute Class4 statistics
• per geographical boxes or in regular 5x5degree
  boxes
• per vertical layers (0-100m, 100-500m, 500-5000m?)

Elementary box patchwork
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Class 4 based on Sea-Ice in the Barents Sea
TOPAZ sea-ice vs SSM/I data. RMS of the ice
concentration error (model-observation) over a
box in the Arctic Ocean. Analysis is compared to
forecast and persistence over a 10-day window
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Status of the intercomparison exercice
definition of metrics

• New description of Class 1, Class 2 and Class 3
  metrics
• Regional areas revisited to fit recommendations'
• Complete description of mooring, sections etc
• Up-grade NetCDF files definition to be consistent
  with COARDS CF1.2 conventions
• Include sea-ice variables in the definitions
• Saving half storage capacity by use of
  compressed NetCDF files (data written short
  instead of floats, using scale_factors)
• Proposition of a set of reference data
  (availability, access)

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Status of the intercomparison exercice
definition of metrics

• Class 1 definition (provided with fortran
  programs)

0 30 50 100 200 400 700 1000 1500 2000 2500 3000
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Status of the intercomparison exercice
definition of metrics

• Class 1 definition (provided with fortran
  programs)
• 2D fields
• The zonal and meridional wind stress (Pa) on top
  of the ocean,
• The total net heat flux (including relaxation
  term) (W/m2) into the sea water,
• The surface solar heat (W/m2) into the sea water,
• The freshwater flux (including relaxation term)
  (kg/m2/s) into the ocean,
• The Mixed Layer Depth (henceforth MLD) (m). Two
  kinds of MLD diagnostics are provided, to be
  compliant with de Boyer Montégut et al., 2004
  and D'Ortenzio et al., 2005. A temperature
  criteria MLD(?) with temperature difference with
  the ocean surface of T0.2C. And a surface
  potential density criteria MLD(?) with a 0.03
  kg/m3 surface potential density criteria.
• The Sea Surface Height (SSH) (m).
• 3D fields
• The potential temperature (K) and salinity (psu).
  
• The zonal and meridional velocity fields (m/s).
• The vertical eddy diffusivity (kz, in m2/s) if
  compressed, first in LOG10!

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Status of the intercomparison exercice
definition of metrics

• Class 1 definition (provided with fortran
  programs)
• 2D fields (for ARC, ACC, NAT, NPA and GLO)
• Sea-Ice thickness (m)
• Sea-Ice concentration (fraction)
• Sea-Ice x and y velocities (m/s)
• Surface snow thickness over sea ice (m)
• Sea ice downward x and y stress (Pa)
• Tendency of sea ice thickness due to
  thermodynamics (m/s)
• Surface downward heat flux in air (W/m2)
• Ancillary data
• The Mean Dynamic Topography (henceforth MDT) (m)
  used as a reference sea level during the
  assimilation procedure. MDT is also called Mean
  Sea Surface Height (MSSH).
• Climatologies of Sea Surface Temperature (SST)
  (K), of surface current (m/s), of MLD (m).
• Climatology of potential temperature (K) and
  salinity (psu) fields from (T,S) used as a
  reference.

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Status of the intercomparison exercice
definition of metrics

• Class 2 mooring/sections
• potential temperature (K) and salinity (psu).
• zonal and meridional velocity fields (m/s).
• Sea Surface Height (SSH) (m).

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Status of the intercomparison exercice
definition of metrics
straight sections (yellow) XBT sections (brown)
gliders sections (purple) tide gauges (blue),
and other moorings (red).
78 vertical levels (WOA and GDEM3.0 standard
levels
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Status of the intercomparison exercice
definition of metrics

• Class 3 definition (transport)

In black, sections without specific class of
computation on the vertical. Transport computed
with classes temperature (red), salinity
(yellow), density (blue) and depth (green).
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Status of the intercomparison exercice
assessment through Class 1-2-3 metrics

• Consistency Monthly averaged fields compared to
• WOA2005, Hydrobase, CARS, MEDATLAS, Janssen,
  climatologies
• De Boyet Montégut MLD climatology
• SST climatology
• Quality Daily fields compared to
• In situ data (Coriolis data server)
• Dynamic topography, or SLA (AVISO products)
• SST (depending on groups)
• SSM/I Sea-Ice concentration and drift products
• Surface currents (DBCP data, OSCAR, SURCOUF
  products)

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Status of the intercomparison exercice Where are
we ?

• Partners involved / status

Status of 3 months hindcast products OpenDAP or FTP addresses Partners main regions of interest
MER Produced TBC NAT, TAT, SPA, TPA, IND, ARC
UKM TBC TBC tbc
TOP TBC TBC tbc
BLK Produced BlueLink OpenDAP  TBC IND, SPA, tbc
MFS TBC TBC tbc
MRI Produced at MRI, provided to University of Hawaii Univ of Hawaii OpenDAP  TBC NPA
HYC TBC TBC tbc
CNF Produced, need to transition to new NetCDF format FTP server of CNOOFS North West Atlantic
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Status of the intercomparison exercice Where are
we ?

• Agenda
• Shift (one month now) for availability of
  products
• Not clear view of intercomparison strength of
  work in the different areas (ie how many groups
  plan a dedicated work looking at more than their
  own hindcast? )
• Target define a deadline to be prepared for the
  Symposium
• Validation and intercomparison of analysis and
  forecast products
• F. Hernandez (Mercator-Ocean), G. Brassington
  (BoM), J. Cummings (NRL), L. Crosnier
  (Mercator-Ocean), F. Davidson (DFO), S. Dobricic
  (ICMCC), P. Hacker (Univ. of Hawaii), M. Kamachi
  (JMA), K. A. Lisæter (NERSC), M. Martin (UK Met
  Office)
• Availability of products (end of July ?????)
• Availability of intercomparison results (mid
  October ????)
• Managing the outcomes
• How do we take profit from feedbacks ?
• Initiative to keep on this activity?

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Assessment diagnostics
SST
SST-WOA05
NOAA RTG SST
SST - RTG
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Assessment diagnostics
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Assessment diagnostics
Salinity-WOA05
Salinity
Surface currents comparison to drifters
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Assessment diagnostics
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Assessment diagnostics
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Assessment diagnostics
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Assessment diagnostics
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Assessment diagnostics
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Assessment diagnostics
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Status of the intercomparison exercice Where are
we ?

• Agenda
• Shift (one month now) for availability of
  products
• Not clear view of intercomparison strength of
  work in the different areas (ie how many groups
  plan a dedicated work looking at more than their
  own hindcast? )
• Target define a deadline to be prepared for the
  Symposium
• Validation and intercomparison of analysis and
  forecast products
• F. Hernandez (Mercator-Ocean), G. Brassington
  (BoM), J. Cummings (NRL), L. Crosnier
  (Mercator-Ocean), F. Davidson (DFO), S. Dobricic
  (ICMCC), P. Hacker (Univ. of Hawaii), M. Kamachi
  (JMA), K. A. Lisæter (NERSC), M. Martin (UK Met
  Office)
• Availability of products (end of July ?????)
• Availability of intercomparison results (mid
  October ????)
• Managing the outcomes
• How do we take profit from feedbacks ?
• Initiative to keep on this activity?