WGOMD: Past, Present, and Future

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WGOMD Past, Present, and Future

• Stephen Griffies
• NOAA/GFDL/Princeton USA
• Working Group for Ocean Model Development (WGOMD)
• Presentation to WGOMD
• 26 August 2007
• Bergen, Norway

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WGOMD Terms of Reference (as of 2000 with slight
revision 2005)

• To stimulate the development of ocean models for
  research in climate and related fields. (recently
  deleted qualifier with a focus on decadal and
  longer timescales at mid-and high-latitudes.)
• To encourage investigations of the effects of
  model formulation on the results of ocean models,
  making use of sensitivity studies and
  intercomparisons.
• To promote interaction amongst the ocean
  modelling community and between this and other
  communities through workshops and other
  activities.
• To stimulate the validation of ocean models when
  used in stand alone mode and as part of a coupled
  ocean-atmosphere model, using oceanographic data
  and other methods, and to advise on the
  observational requirements of such studies.
• To publicise developments in ocean models amongst
  the climate modelling community.
• To collaborate with other activities in areas of
  overlapping responsibility.
• To advise on ocean modelling and related issues
  and to report on its activities to the JSC/CLIVAR
  WGCM and CLIVAR Scientific Steering Group.
• Two sets of parent organizations are often
  cumbersome for WGOMD (e.g., two different
  international meetings to report to each year).

ToR are largely applicable today, with perhaps
some modifications based on new developments in
the community.
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WGOMD Assumptions

• Ocean models are relevant to understanding
  climate and predicting potential future changes.
• The space-time scales relevant for WGOMD
  considerations extends from the global climate
  scale to the regional and increasingly the
  coastal scales.
• Scientifically based model fundamentals produce
  robust model tools for use in climate science.
  This is the science of ocean models
• Dynamical assumptions
• Numerical methods
• Physical parameterizations
• Rational, complete, and pedagogical model
  documentation
• Well defined and fully documented experimental
  designs for model simulations are essential to
  realize robust results which can be reproduced by
  other groups. Absent the full documentation of
  model designs, one is doing irreproducible model
  integration (not science). This is the science of
  ocean modelling
• Forcing datasets
• Bulk formulae
• Restoring terms
• Coupling methods
• Integration times
• Analysis methods

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State-of-science for models and modelling

• Ocean models are not mature.
• Ocean modelling practice is not mature (i.e.,
  global ocean-ice simulations are not generally
  comparable between groups).
• Methods used are often not robust, with ad hoc
  and undocumented steps employed to get the
  models running. This situation leads to
  modelling being as much an art as a science.
  That is, the simulations are often not
  reproducible (even by the group performing the
  original simulation!).
• Given the growing importance of ocean models for
  understanding and predicting global and regional
  climate, the models and the experimental design
  must be given a well documented scientific
  foundation.

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WGOMD mission

• A central mission of WGOMD is to facilitate the
  maturation of ocean models, and the use of ocean
  models in well defined and reproducible ocean
  modelling simulations.
• WGOMD aims to realize this mission by providing
  pedogogical peer-review survey papers that
  document models and the experimental design of
  simulations.
• It also does so by organizing topical workshops
  that bring elements of the oceanography community
  together to discuss research and development
  areas relevant to increasing the scientific
  integrity of models and their simulations.
• Realizing this mission (or some aspect of it)
  allows WGOMD to provide scientifically based
  advice to other Clivar panels and to WGCM.
• This mission remains ongoing, with some success.
  However, further efforts are required to make
  routine use of ocean models by a scientifically
  literate researcher a process that produces
  useful scientific results.

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Key contributions of WGOMD

• Review paper Pedagogically documents
  state-of-art in ocean climate models (Griffies
  etal (2000))
• Workshops Topical workshops that facilitate
  collaboration, communication, and education
• Princeton/GFDL 2004 State-of-art in Ocean
  Climate Modelling
• Hobart/CSIRO 2005 Southern Ocean Modelling
• Bergen 2007 Numerical Methods for Ocean Models
• CORE Benchmark experiments for global ocean-ice
  models. Peer-review paper illustrates CORE-I with
  seven ocean-ice models each run for 500 years
  (Griffies etal in prep).

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WGOMD review article (2000)

• Pedogogical survey of ocean climate model methods
  and parameterizations
• Highlighted vertical coordinates as key for model
  algorithms, with many complementary attributes
  between coordinates.
• Influenced AR4 ocean climate model developments.
• A basis for ongoing research efforts at improving
  model fundamentals.

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Princeton/GFDL Workshop 2004 State of the art
in ocean climate modelling

• Key developers of AR4 ocean climate models
  discussed their methods, parameterizations, and
  results.
• Experts in ocean physics and numerics scrutinized
  the AR4 models and made recommendations for next
  round of IPCC ocean models.
• Community input to the WGOMDs efforts at
  establishing an OMIP. A key outcome was to
  propose CORE as a science-based collaborative
  project, rather than push forward with a
  mandatory OMIP, as such was was considered
  premature.

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Hobart Workshop 2005 State of the art in
Southern Ocean Modelling

• Southern Ocean is key to represent with high
  fidelity in climate models, as it represents a
  huge sink for heat and carbon, and the processes
  active have importance to all ocean basins.
• Science workshop discussed and debated methods of
  simulating and analyzing Southern Ocean physical
  and biogeochemical processes.
• Ten lectures with discussions provided
  pedagogical surveys of key aspects of the
  Southern Ocean.

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Bergen Workshop 2007Numerical Methods for Ocean
Models

• Discuss and debate novel methods for developing
  the next generation of ocean models for global,
  regional and coastal applications.
• Bring together key practitioners and algorithm
  developers for eight provocative and pedagogical
  sessions.
• Enhance communication amongst a community of
  algorithm developers who typically do not have
  the opportunity to gather in such focused
  workshop settings.

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Coordinated Ocean-ice Reference Experiments
(COREs)

• Benchmark simulations for global ocean-ice models
• CORE-I proof of concept project includes seven
  model groups with three ocean model classes
  (geopotential, isopycnal, hybrid).
• A step toward an Ocean Model Intercomparison
  Project (OMIP)

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End of Saturdays material
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WGOMD panel meetings the road to CORE

• Miami, Sep2000
• Led to the review paper Developments in Ocean
  Climate Models (Griffies etal, Ocean Modelling
  2000).
• Santa Fe, Mar2001
• Meeting was the first of many to discuss metrics
  for ocean climate model evaluation. Also launched
  the Pilot-OMIP.
• MPI Hamburg, May2002
• Start of Pilot-OMIP using German (MPI) repeating
  annual mean forcing (based on ECMWF)
• Recognition of the nontrivial nature of
  developing a suitable dataset to force global
  oceanice models on centennial and longer time
  scales
• Villefranche Apr2003
• NCAR (Bill Large) announced development of
  alternative oceanice model forcing with
  repeating annual year and interannual forcing
  based on NCEP satellites. GFDL to provide
  support.
• GFDL Princeton Jun2004
• Science workshop (100 participants) State of
  the art in ocean climate models
• WGOMD recommends the use of Large and Yeager
  (2004) dataset for oceansea ice model forcing
  NCAR and GFDL to support future upgrades to the
  dataset.
• CSIRO Hobart Nov2005
• Science workshop (100 participants) Modelling
  the Southern Ocean
• Initial reports from groups using Large and
  Yeager (2004) aim to have peer-reviewed
  manuscript by end of 2006 with 4-5 modelling
  groups participating.
• Bergen Aug2007
• Science workshop (100 participants) State of
  the art in numerical methods for ocean climate
  models co-organized with Layered Ocean Model
  leadership.
• Report on the CORE-I results (seven ocean-ice
  models run 500 years).

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Miami/RSMAS Sept 2000

• Panel members Boening (chair), Bryan,
  Chassignet, Griffies, Gerdes, Hasumi, Hirst,
  Treguier, Webb
• Discussion of model development, with focus on
  global models planned for IPCC-AR4.
• Highlighted need to develop suite of model
  metrics for use in evaluating simulations. An
  ongoing theme!
• Panel members homework to summarize model
  development in their local sphere led to a review
  paper Developments in Ocean Climate Models
  (Griffies etal, Ocean Modelling 2000) which
  documented the state-of-the-art in ocean climate
  models.
• Gerdes presented results from German OMIP
  (MPI-HOPE and AWI-MOM2) which initiated the idea
  of a broad based ocean-ice model comparison
  project.
• German OMIP used the MPI-dataset from Frank
  Roeske, based on ECMWF. This dataset is proposed
  for a pilot comparison project.

WGOMD
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Santa Fe May 2001

• Panel members Boening (chair), Bryan,
  Chassignet, Griffies, Gerdes (missing), Hasumi,
  Hirst, Treguier, Webb
• Formal proposal for WGOMD sponsored pilot-OMIP
  managed by Frank Bryan. Seven groups volunteered
  to participate. Use the MPI-Roeske dataset to
  force the models. Allow modellers to use their
  own bulk formulae and methods for salinity
  restoring. 100 year runtime.
• Discussed importance of standard metrics for use
  in evaluating ocean simulations.
• In general, the difficulty of designing an OMIP
  was under-estimated (forcing data, experimental
  design, bulk formulae, integration length).
  Additionally, many of the main players were
  committed to developing coupled climate models
  for AR4, with that work complementary to the
  ocean-ice OMIP simulations, but often at the cost
  of fully developing the ocean-ice experimental
  design and code framework. These issues would
  plague the project for the next few years.

WGOMD with guests
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Hamburg/MPI May 2002

• Panel members Boening (chair), Bryan,
  Chassignet, Griffies, Gerdes, Hasumi, Hirst,
  Treguier, Webb
• Focused discussion on PILOT-OMIP.
• Larry Gates (founder of AMIP) encouraged us to
  move forward with OMIP as coordinated through
  PCMDI.
• Mojib Latif noted that modellers would not fully
  agree on a forcing dataset, so we should just
  agree on one set and run the models using the
  same protocol.
• However, we were still missing some points
• Modellers agreed only on a rough experimental
  design. Some were even doing ocean-only runs,
  which are distinctly not the focus. Such is fine
  for testing purposes, but precluded a focused
  comparison.
• Not all centres had been routinely running
  ocean-ice simulations using prescribed
  atmospheric data most either ran ocean-alone or
  fully coupled climate models. Hence, code needed
  to be developed, and that added much time to the
  project.
• The nontrivial sensitivity of simulations to
  different bulk formulae was not yet appreciated.
• 100 year simulations still considered adequate,
  but later were seen to be insufficient for
  overturning circulation (could have been
  guessed!).
• The inability of the modelling centres to agree
  on the forcing dataset precluded the buy-in from
  some key players (e.g., NCAR).

WGOMD with guests
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Villefranche-sur-Mer 2003

• Panel members Boening (chair), Bryan,
  Chassignet, Griffies, Gerdes, Hasumi, Hirst,
  Treguier, Webb
• Broad discussion and debate of datasets used to
  force ocean-ice simulations.
• Bill Large from NCAR highlighted some egregious
  problems with the ECMWF and NCEP reanalysis data,
  which is the basis for the Roeske forcing fields
  from MPI (ECMWF). He proposed a new product
  based on NCEP with satellite products replacing
  certain reanalysis fields.
• WGOMD chose to pursue the NCAR data in order to
  entrain the bulk of the modeling community. GFDL
  in particular agreed to work closely with NCAR to
  prototype their dataset with a GFDL-MOM
  configuration.
• Another reason to eschew the MPI dataset was that
  is became clear it was poorly supported (Roeske
  leaving the field), and thus became a risky
  choice for large comparison projects.

WGOMD and guests with Atlantic Panel
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Princeton/GFDL 2004

• Panel members Boening (chair), Bryan,
  Chassignet, Drange, Griffies, Gerdes, Hasumi,
  England (missing replaced Hirst), Treguier,
  Banks (replaced Webb)
• Community feedback comparison of global
  ocean-ice models is of scientific interest, so
  the development of a WGOMD sanctioned common
  benchmark simulation is highly useful.
• The interest in establishing a formal OMIP was
  less clear at this point, given the many
  questions of how to run an ocean-ice model with
  large uncertainties in forcing data
• CORE proposed as a scientifically interesting
  exercise whereby a number of groups will run the
  Large and Yeager (2004) dataset forcing their
  global ocean-ice models for 500 years. No
  pretense (yet) that this is an OMIP, so no
  efforts (yet) made to involve PCMDI.

WGOMD workshop participants
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Hobart/CSIRO 2005

• Panel members Boening (co-chair), Banks,
  Chassignet, Drange, England, Gerdes (ex-officio),
  Greatbatch (missing), Griffies (co-chair),
  Hasumi, Holland (replaced Bryan), Treguier
• Results from 500 year CORE-I simulations starting
  to be submitted (CCSM-POP, GFDL-MOM, ORCA-OPA).
  However, other interested groups remain unable to
  get the code together, develop an appropriate
  experimental design, nor garner sufficient
  computer time.
• Early results point to the sensitivity of
  simulations to fresh water forcing. How strong
  should salinity be restored? This question was
  left for each model group to decide. No formal
  recommendation made part of the CORE design.
• With only three groups, and with no isopycnal nor
  hybrid models, the project remained sub-critical.
  

WGOMD and guests
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Bergen 2007

• Panel members Boening (emiritus), Banks,
  Chassignet, Drange, England (absent), Gerdes
  (emiritus), Greatbatch, Griffies (chair),
  Tsujino, Danagasoglu (representing Holland),
  Madec, Treguier (emiritus)
• Seven ocean-ice models run for 500 years with
  Large and Yeager (2004).
• four geopotential
• two isopycnal
• one hybrid
• CORE-I has reached a critical mass
• Wide variety of results, with more questions
  raised than answered.
• Broad comparison projects such as this achieve
  much by raising questions, which then motivate
  further research.
• Without the comparison, questions remain unasked,
  and thus unanswered.
• Peer-review document with 20 authors to be
  submitted to Ocean Science (EGU online journal
  founded by David Webbformer WGOMD member).

WGOMD and guests in Bergen
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What is next for WGOMD?

• CORE-I ? OMIP?
• CORE-II (interannually varying)
• CORE-III (Greenland ice-melt perturbation)
• CORE-IV (heat perturbation)
• Intermediate coupled models
• Data over-ride coupled models
• WGOMD Repository for Evaluating Ocean Simulations
  (WGOMD REOS)
• Another workshop for 2009?
• Co-chair
• General membership issues

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CORE-I ? OMIP?

• Are we ready to entrain PCMDI?
• Maintain repository of model results ancilliary
  code, such as bulk formulae and river mapping
  scheme
• Advantage expose datasets to larger community
  analysis, and maintain better version control on
  data and code
• Disadvantage PCMDI requires datasets to fit into
  their constraints (e.g., data must be mapped to
  spherical grid)
• WGCM should CORE-I submission to PCMDI be part
  of the AR5 model database?
• Propose make CORE-I a recommendation rather than
  a requirement.
• Propose PCMDI involved through WGCM oversight,
  not WGOMD oversight.

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CORE-II interannually varying forcing

• Only a few cases with interannually varying Large
  and Yeager (2004).
• How to initialize (ocean and ice)?
• What about salinity restoring? Same as CORE-I?
• How many cycles of the forcing dataset?
• What to analyze (metrics)?
• Action item subgroup of interested WGOMD
  participants should develop an experimental
  design and run a mini-comparison.
• Who is interested? Who will take charge?

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CORE-III Greenland ice melt

• Have only run with 2-degree version of the
  GFDL-MOM, using MPI-OMIP dataset, and various
  other boundary conditions.
• Interactive atmosphere model desirable due to
  interest in perturbations, and dis-interest in
  mixed boundary condition instabilities.
• Survey questions
• Any group interested in pursuing this experiment
  with ocean-ice model?
• What about coupled climate model? GFDL
  interested, but focus for next 6months (at
  least) on model development
• Can/should WGOMD investigate a simple atmospheric
  model for use in comparisons? (e.g., SPEEDY? UVic
  EBMM)
• Interested parties? Who will coordinate?

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CORE-IV global warming perturbation

• Within the present CORE-I design, consider one or
  both of the following perturbations
• Add xx W/m2 uniformly over globe
• Increase the atmospheric air temperature
  uniformly over the globe by yy degC
• Force ocean-ice models with multi-model ensemble
  mean (is this at PCMDI?). Could compare to CMIP
  results.
• Purpose determine centenial-scale response of
  ocean-ice system to global warming sorts of
  perturbations.
• Action item?

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WGOMD Repository for Evaluating Ocean Simulations
(REOS)

• Purpose Web-based tool for evaluating ocean
  simulations.
• Proposal WGOMD maintained web page containing
  input from the modelling, observational, and
  analysis communities which provide guidance and
  oversight for methods of evaluating ocean
  simulations.
• Datasets
• Analyses/syntheses
• already a Clivar page http//www.clivar.org/data/s
  ynthesis/directory.php
• Tools (e.g., methods for sampling model output as
  in the observations)
• Annotated bibliography of relevant papers
• Forum to discuss methods and best practices
• e.g., how much confidence should one place in
  certain metrics or datasets?
• Action item feedback and input to Anna and
  Stephen

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WGOMD/WGNE

• Should WGOMD expand its focus to include elements
  of the following
• Prediction (especially decadal)
• Assimilation
• Regional modelling
• Operational modelling/forecasting
• Arguably we have the expertise on WGOMD to do so,
  at least to some level.
• Action items?

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2009 panel meeting

• Continuing our new tradition of meeting each 18
  months, next panel meeting will be first half of
  2009.
• Location Given the tight budget constraints felt
  by many groups, it will need to be either North
  America or Europe.
• Past locations
• Miami(2000)
• Santa Fe(2001)
• Hamburg(2002)
• Villefranche(2003)
• Princeton(2004)
• Hobart(2005)
• Bergen(2007)
• Proposal April 2009 at Hadley Centre (check
  conflicts)

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2009 Workshop?

• Science workshop to accompany the WGOMD panel
  meeting.
• 2009 is roughly 20 years after the famous Gent
  McWilliams (1990) paper which has been
  influential in the ocean parameterization world.
• Proposal Representing and parameterizing the
  ocean mesoscale 20 years after Gent and
  McWilliams (1990)

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Membership

• Anne Marie Treguier now emiritus, with Gurvan
  Madec replacing.
• Claus Boening stepping down. Richard Greatbatch
  replacing.
• Marika Holland stepping down. Proposed Gokhan
  Danabasoglu to replace.
• Propose one new member, with focus of this
  persons expertise on topic of interest for
  future WGOMD e.g., prediction? assimilation?
  Unconstrained by geographic region.

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Griffies ? Griffies co-chair

• I have been member of panel since 2000.
• Co-chair and chair since 2004 (three panel
  meetings and three workshops)
• Time for new ideas and energy.
• Proposal Helene Banks to co-chair starting this
  year, to help balance the panels expertise on
  model applications, especially towards climate
  prediction, metrics, evaluation.
• Proposal 2009 workshop/meeting will be my last
  as chair, at which time may wish to consider
  another co-chairfuture discussions.

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References

• Gerdes, Hurlin, and Griffies (2006) Sensitivity
  of a global ocean model to increased runoff from
  Greenland. Ocean Modelling, vol. 12, pages
  416-435.
• Griffies, Boening, Bryan, Chassignet, Gerdes,
  Hasumi, Hirst, Treguier, and Webb (2000)
  Developments in Ocean Climate Modelling, Ocean
  Modelling, vol. 2, pages 123-192.
• Griffies and coauthors (2008) A proposal for
  Coordinated Ocean-ice Reference Experiments
  (CORE). In preparation.
• Large and Yeager (2004) Diurnal to decadal
  global forcing for ocean and sea-ice models the
  data sets and flux climatologies, NCAR Technical
  Report.

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Ocean WGNE - draft terms of reference (from a
WCRP perspective)

• In collaboration and consultation with other
  groups of sponsoring organizations
• (i) Review the development of ocean models for
  use in coastal to global scale operational and
  climate prediction taking into account the needs
  for representation of physical, biogeochemical
  and ecological components, and the coupling
  between these and other system components (in
  particular the atmosphere, land and cryosphere)
  .Propose numerical experiments aiming to refine
  numerical techniques and the formulation of
  physical, biogeochemical and ecological processes
  in ocean models, taking account of the optimal
  techniques for provision of ocean model forcing.
• Promote the development of new methods for ocean
  prediction.

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Ocean WGNE - draft terms of reference (from a
WCRP perspective)

• (iii) Design and promote co-ordinated experiments
  for
• validating model results against observed oceanic
  properties and variations and diagnosis of
  shortcomings
• exploring the intrinsic and forced variability
  and predictability of the circulation of the
  ocean on all scales and its impacts on ocean
  biogeochemistry and ecology on short to extended
  ranges
• assessing the intrinsic and forced variability of
  the ocean on a range of time-scales, including
  the interactions with biogeochemical and
  ecological components.
• (iv) Promote the development of data assimilation
  methods for application to ocean predictions, and
  for the estimation of derived climatological
  quantities (ocean synthesis/reanalysis).
• (v) Promote the timely exchange of information,
  data and new knowledge on ocean modelling through
  publications, workshops and meetings.
• (vi) Advise the sponsoring organizations on
  progress in ocean modelling.