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WGOMD: Past, Present, and Future

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Ocean models are not mature. ... Results from 500 year CORE-I simulations starting to be submitted (CCSM-POP, GFDL-MOM, ORCA-OPA) ... – PowerPoint PPT presentation

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Title: WGOMD: Past, Present, and Future


1
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

2
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.
3
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

4
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.

5
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.

6
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).

7
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.

8
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.

9
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.

10
Bergen Workshop 2007 Numerical 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.

11
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)

12
End of Saturdays material
13
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).

14
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
15
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
16
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
17
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
18
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
19
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
20
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
21
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

22
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.

23
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?

24
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?

25
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?

26
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

27
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?

28
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)

29
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)

30
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.

31
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-chair…future discussions.

32
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.

33
Blank slide
34
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.

35
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.
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