Ocean Modeling Workshop at NCEP

14-15 January 2008

Summary notes, Hendrik Tolman, Editor.

Final version

March 30, 2008

[Background]{.underline}

A two day ocean modeling workshop was held a NCEP on January 14 and 15,
2008. The goal of this meeting was two fold. The meeting helped
establish a comprehensive ocean modeling plan for NCEP, while working
towards a (marine) Ecosystem Forecast System (EFS) for NOAA, lead by
NOS. Attendance was by invitation, with wide representation from NOAA,
other government entities, and academia.

The goals of the meeting are rooted in a July 2004 report of the NOAA
Science Advisory Board on Ocean Modeling at NCEP, and the NOAA response
to this report with a letter from Vice Admiral Lautenbacher to the
Science Advisory Board in 2005. In these documents NOAA/NCEP was charged
to become the "computational backbone" for operational physical ocean
modeling within NOAA. In particular the response to the report states
that the charge is

> "*to develop a national backbone capability for ocean, coastal ocean
> and Great Lakes modeling as part of an integrated operational Earth
> System Model ...* \[to\] *serve as the foundation for operational
> environmental prediction for a diverse array of customers and
> partners."*

Within NOAA, the primary responsibility for (weather- and) basin-scale
physical modeling resides with NWS/NCEP[^1], whereas the responsibility
for regional and coastal scales is shared by partners inside and outside
NOAA (NOS, OAR, IOOS Regional Associations, etc.), with relevant
modeling efforts to be transferred to NCEP operational super computing
facilities. The primary responsibility for the integrated Ecosystem
modeling resides within NOS, with individual responsibilities mainly
residing within NOS and NMFS. These efforts can only succeed as a part
of a national effort, with a strong partnerships with the Navy, NASA,
USCG, USACE, academia and industry.

[Overview of meeting]{.underline}

The first day of the meeting focused on user requirements, including
temporal and spatial scales and products needed. The second day focused
on modeling capabilities, challenges and needs. Presentations covered
global and regional physical ocean modeling and ecosystem modeling. The
agenda, copies of the presentations and an attendance list can be found
at the web site
<http://polar.ncep.noaa.gov/mmab/meetings/Workshop08/agenda_v4.3.html>.
The agenda included a list of questions to be addressed during
discussions and in the presentations. Based on the presentations and
discussion, the following general observations can be made.

1)  Temporal scales:

> The focus of most applications of ocean and ecosystems modeling
> considered at the workshop is at the weather (synoptic) time scales;
> i.e. short term, real time, operational forecasts up to weekly time
> scales, resolving diurnal and tidal cycles. Additional applications
> consider seasonal to annual time scales in a real-time operational or
> more incidental (operational) environment.
>
> There are requirements for modeling decadal and longer time scales;
> however, the focus here is on the real-time operational aspects of
> ocean and ecosystems modeling. The longer time scales share some but
> not all requirements with shorter time scale applications. Real-time
> modeling focuses on a proper description of features, where limited
> numerical diffusion is essential, whereas a focus of the larger time
> scales is on strict conservation of relevant quantities and control of
> model drifts as a function of forcing and/or coupling. Considering
> this, it is not productive to enforce unified modeling capabilities
> across all time scales in view of or present state of knowledge.
>
> Finally, long time series (several decades) of ocean circulation
> reanalysis data are needed to develop certain classes of ecosystems
> models, and are essential in ocean modeling. These simulations form an
> important element in OSSEs. Although the underlying models cannot be
> considered operational in the same sense that daily forecasts are
> considered operational, they share assimilation and modeling
> requirements with the real-time operational system; hence operational
> modeling systems are highly suitable to be the basis of reanalyses.
> Within NOAA, the responsibility of modeling at these time scales lies
> with GFDL.

2)  Spatial scales:

> For the main ocean modeling applications at the shorter weather time
> scales, an essential requirement is that ocean models resolve dominant
> oceanic features. For global models this requires resolving mesoscale
> eddies, or a resolution of about 1/12º or better. For regional and
> coastal applications in both physical and ecosystem modeling, higher
> resolutions are required with typical resolutions of regional models
> of the order of kilometers and, in coastal and estuarine resolutions
> as small as tens of meters.
>
> For seasonal to annual time scale applications, such high resolutions
> are not feasible due to the length of the model runs, and the focus on
> probabilistic modeling with ensembles of model runs. At these time
> scales lower resolution ocean and ecosystem models may be acceptable
> as an incremental improvement of such models by means of coupled
> modeling. Research remains to be done on the cost-benefit of
> eddy-resolving model applications versus sub-grid parameterizations of
> such processes

3)  Ecosystems models.

> With respect to numerical ocean modeling, several types of ecosystem
> processes or models can be identified:

a.  Ecological processes that influence the physical modeling through
    direct feedback, for instance, sediment transport and turbidity
    related to chlorophyll and particles influences the penetration
    depth of incoming radiation and hence SST and other physical
    properties of the ocean. These processes need to be considered for
    direct inclusion in the physical models to increase the accuracy of
    the physical prediction models. Note that this is also true for
    materials entrained/suspended in the water column and inorganic
    matter such as silt/sediment. Inclusion of such processes could be
    by parameterization or by explicit modeling.

b.  Other tracer and biochemical processes that do not directly or
    notably influence the circulation can be treated with one-way
    coupling. This can be done with down-stream models, or with models
    running side-by-side in a one-way nested mode. The former will put a
    stress on disk storage, the latter on simultaneously available
    computational resources.

c.  Fish stock and comparable ecological models. Presently such models
    are mostly based on population structure and dynamics (e.g.
    predation and natural mortality). Future models are expected to be
    more dependent on physical modeling, but require aggregated rather
    than instantaneous data from physical models. For such models,
    efficient access and aggregation of historical and/or climatological
    data (reanalyses) becomes essential, as well as seasonal and longer
    term forecasts. Such ecosystems models are typically run as separate
    models downstream from the physical ocean models.

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4)  Data requirements.

> The data from physical ocean models needed by users, downstream models
> or coupled models depends strongly on the applications considered.

a.  Direct operational users such as OPC, TPC, HAZMAT and USCG mostly
    require water levels (including coastal inundation) and near-surface
    currents. The Navy requires additional model data for tactical
    purposes, particularly related to ocean acoustics.

b.  Nested physical ocean models require a full description of the ocean
    state at high temporal resolution to provide boundary conditions and
    possibly initial conditions.

c.  Ecosystems models typically require information describing the state
    of the ocean, i.e., temperature and salinity profiles, 3D currents
    (Lagrangian transport) , mixed layer depth, turbulence
    characteristics and possibly water levels. Time scales have been
    discussed above.

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5)  Capabilities.

> Operational centers focusing on weather and seasonal time scales are
> focusing on a set of software packages, particularly HYCOM and ROMS
> for ocean circulation, ADCIRC for (coastal) tides and surges and
> WAVEWATCH III for ocean waves. MOM3 and MOM4 are used for physical
> ocean modeling at climate time scales. Global physical ocean models
> also require dynamic description (models) for sea ice. Structured
> grids are acceptable offshore, where ocean features are not strongly
> linked to bathymetric features. Coastal circulation and inundation
> strongly depend on local bathymetric and topographic features. In such
> conditions, unstructured grids are beneficial to properly resolve
> dominant features in the bathymetry and topography. Unstructured ocean
> circulation models are available in the academic environment, but have
> not (yet) made the transition to operational centers. The Earth System
> Modeling Framework (ESMF) appears to be the method of choice to enable
> dynamic coupling between model elements in a model comprehensive earth
> system or ecosystem model. All main operational federal forecast
> centers in the US are moving toward an ESMF model coupling
> environment.
>
> The majority of experience with operational or near real-time
> basin-scale (global) ocean circulation models resides with the Navy,
> with practical global model applications with resolutions of up to
> 1/12º. Regional and coastal experience resides with many
> organizations: NOS now has Operational Forecast Systems running in
> nine water bodies (4 ports and the five Great Lakes) and is working
> towards a regional modeling approach in the context of a standardized
> Coastal Ocean Modeling Framework; IOOS RAs and academia share a wealth
> of experience with a plethora of models and approaches. (although most
> of these cannot be considered operational models in the same sense
> that weather models are).

6)  Challenges

> Many challenges were identified at the work shop. The main challenges
> identified are (not prioritized):

a.  Skill assessment and validation. Standards should be promoted over
    actual statistics. Attention needs to be paid to accuracy and impact
    of boundary data for regional models. Diagnostic capabilities need
    to be developed in this context. Example: use of Taylor diagrams.

b.  Availability of observational data. The community needs to advocate
    that all data collected is available in real time to a broad public.
    This is particularly a need for real time operational centers. Such
    centers can also be distribution points and/or data clearing houses
    (example NDBC). Data example: HF radar.

c.  Bathymetry and coastline data form a specific class of data with
    specific challenges (common datum).

d.  Availability of and access to model data. Ideally all model
    parameters are available at model resolution, but with capabilities
    to aggregate and sub-sample data. Experience resides with NODC,
    NCDC, NCDDC, NOPP partners and IOOS RAs (SURA). Data volumes require
    dedicated and stable funding, based on realistic data volume
    estimates.

e.  Transition of NOAA operational computing to NCEP platforms. This is
    a SAB recommendation and a first step toward coupled modeling. A
    challenge is to grow NCEP operational computing funding consistent
    with additional computing requirements. This will require a
    realistic estimate of necessary computer resources (including
    storage).

f.  Unification and streamlining of regional and coastal modeling
    efforts without suppressing a healthy diversity in modeling
    approaches. In this context it is essential to promote modeling
    *frameworks* rather than individual *models*.

g.  Transition to operations. Transitioning a new model into a full
    operational environment as at NCEP requires an engineering effort
    similar to that required to develop the model itself. This effort
    can be greatly reduced if the new model is developed inside the
    operational modeling framework. In this context, experiments and
    research projects should ideally use or be fully consistent with the
    operational modeling environment. Particularly the European Centre
    for Medium range Weather Forecasting (ECMWF) has been very
    successful with this concept, aided by the fact that ECMWF can
    direct some research funding.

h.  Coupling of existing physical and ecosystems models. A transition to
    ESMF compliant codes requires a non-trivial code development effort.

i.  Configuration management. For jointly developed models (HYCOM,
    WAVEWATCH III, ADCIRC, ROMS, etc.) configuration management is
    essential, and needs to have dedicated and stable funding. The
    configuration management should include both the practical version
    control through subversion or other standard approaches (i.e. a
    'code keeper'), and a vehicle to guide the model development and
    elements to be added to official model releases (i.e., a model
    control board).

j.  Development of unified assimilation approaches or frameworks. Such
    efforts for assimilation lag those of the accompanying physical
    models. Advanced assimilation schemes require more resources than
    the underlying physical models. Assimilation will become much more
    complex for coupled weather-ocean-ecosystems models.

k.  OSSE-OSE and reanalysis require large resources, but are essential
    to steer operational model development. From an operational
    perspective OSSEs should be designed for maximum consistency-impact
    on operational modeling.

l.  Ensemble ocean modeling is still in its infancy. Coupled
    ocean-atmosphere modeling will promote this. Ensembles require large
    computing resources, and a proper balance between spatial resolution
    and probability resolution (number of ensemble members) needs to be
    found. The required ocean model resolution for such coupled models
    is not yet clearly established. Ensembles could possibly become a
    relatively cheap alternative to OSSEs.

m.  Accurate river runoff data is required for physical circulation
    models at all scales. For smaller tributaries with shorter time
    scale of runoff fluctuations, both observations and forecasts are
    essential.

n.  Resolving (internal) tides in ocean models and accurately modeling
    tides in full 3D ocean models requires model development and
    aggravates already existing data storage and distribution issues
    (hourly tidal information is required whereas presently model data
    are typically saved at 6 hour intervals).

o.  A major challenge is that the responsibility of the ocean and
    ecosystems modeling within NOAA is spread across line offices.
    Moreover, this effort can only be successful if it is based on a
    strong partnership with the Navy, academia and international
    efforts. This requires consistent long-term interdisciplinary
    funding to and from all major partners included. To promote such
    ocean and ecosystem modeling, a clear business model needs to be
    developed.

p.  Within the funding context, transitioning from developmental funding
    (like NOPP) to timely operational (long-term) funding is a major
    challenge.

q.  Building a critical mass of in-house expertise. This is a growing
    field, and it is difficult to find qualified personnel. Partnerships
    can help develop expertise, but cannot be a substitute for in-house
    expertise. Gaps in funding (e.g. from research to operational
    funding) can seriously erode in-house expertise.

r.  Common terminology across disciplines; we need to understand that
    the word model means something different at different places
    (compare NCEP with numerical models and NMFS with stock models).
    Similarly, there are operational 7/24 requirements versus
    operational requirements to periodically produce reports or
    inventories.

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7)  Recommended action points:

> The discussions during the presentations and the discussion sessions
> identified some action points. The main suggested action points are
> (not prioritized):

a.  Promote community involvement. IOOS-MAST appears to be a preferred
    vehicle, but it is acknowledged that the IOOS RAs are not yet
    completely comfortable with (supportive towards) the modeling
    community. We need to convince IOOS (and NOAA-IOOS) to subscribe to
    the modeling effort (possibly including funding). Modeling should be
    an integral part of IOOS in all aspects.

b.  Consider the establishment of a test bed facility for ocean and
    ecosystems models. This will promote community involvement, but will
    require access to and control over research funding to be effective.
    Good examples include the Joint Hurricane Test bed (JHT) and the NOS
    Model Evaluation Environment that has been first tested in the
    Delaware Bay by the Coast Survey Development Laboratory.

c.  Develop a CONOPS for the ocean and ecosystem modeling backbone.
    Presently many elements of a backbone exist, but they do not
    comprise a coherent backbone. A clearly developed CONOPS can help
    the development of the backbone concept and help to define roles and
    responsibilities. Operational agencies like NOAA and Navy are
    ideally positioned to provide and/or develop a CONOPS, but community
    involvement is also essential.

d.  Address HYCOM code keeping. Presently, the Navy acts as the HYCOM
    code keeper as part of a NOPP project. After this project, there are
    no resources identified to continue this code keeping activity. For
    effective community modeling, it is essential that this issue is
    addressed

e.  Code keeping for other jointly developed models (ADCIRC, WAVEWATCH
    III, ROMS, etc.) also require stable funding commitments.

f.  Identify teams to start projects and pursue funding at several
    levels.

    i.  Operational agencies need to budget for ocean and ecosystem
        modeling efforts consistent with requirements. For NOAA, funding
        across line offices poses an additional problem.

    ii. IOOS (NOAA-IOOS) needs to balance, data management, observations
        and modeling efforts, in their funding portfolio.

    iii. Collaboration across the community is most effectively promoted
         if appropriate funding is available. ONR and IOOS must play a
         role in this. NOPP may be a proper vehicle to promote this.
         Several possible projects have been identified and should be
         pursued further. Note that such funding can accelerate
         operational modeling, but cannot substitute for it.

         -   NOPP (or other) demonstration projects to actively link
             large scale ocean modeling at NCEP with the Coastal Ocean
             Modeling Framework of NOS focusing on one or several of the
             IOOS RAs to establish a practical ocean modeling framework.

         -   Follow-on for the present NOPP project for HYCOM. Possible
             subjects for further development are inclusion of global
             (internal) tides, improving model physics either within the
             ocean model, or through coupling to other environmental
             models (wind waves, chlorophyll, etc.). Data dissemination
             needs to be an integral part.

         -   Follow-up for present NOPP focusing on data assimilation
             and/or data assimilation frameworks.

         -   Start demonstration projects focusing on linking physical
             modeling and ecosystems models for fisheries (see five
             suggested studies in presentation by Jonathan Phinney on
             first day of workshop).

         -   Ocean reanalysis projects.

         -   OSSE and OSE projects (work shop being held in Miami in
             April 2008).

         -   NOAA-USACE lead effort to move toward next generation of
             wind wave models with seamless model suite from the deep
             ocean to the surf zone.

[Implications for NOAA]{.underline}

As mentioned in the introduction, the workshop had a focus on both ocean
and ecosystems modeling in general, and implications for NOAA ocean
modeling in particular. The summary of results of the workshop will now
shift to its narrower focus. Implications for NOAA can be centered on
two main issues; the development of a concept of operations, and
addressing funding issues.

1)  Concept of Operations (CONOPS):

> NOAA is uniquely positioned to provide a backbone ocean modeling and
> data distribution framework due to the operational orientation of, in
> particular, the NWS. This operational focus includes:

-   High-reliability computing (99% or higher data availability
    guarantee).

-   7/24 support of computing and data dissemination.

-   Liability coverage for official government issued guidance and
    forecast products.

-   Dissemination of data to the public through Weather Forecast Offices
    (WFOs). This existing capability could be expanded to provide
    ocean-oriented product to the public.

> Note that the Navy shares many operational aspects of modeling with
> NOAA, except for the mission to provide these data to the general
> public. As part of an active partnership, NOAA could act as a portal
> to provide public access to (unclassified) model data from the Navy.
> Note that due to the difference in missions, both NOAA and the Navy
> are required to maintain their own model suites.
>
> For physical ocean modeling, several major partners can be identified
> within NOAA, all with a distinct responsibility in a general Concept
> of Operations:

-   NWS: Provide daily high-resolution global ocean modeling products to
    the public, possibly with increased resolution at the US coast.

    -   Provide boundary data for regional models.

    -   Provide global data for (downstream) ecosystems models.

    -   Provide a modeling backbone for ocean modeling as part of
        coupled weather modeling within the NWS.

    -   Provide a starting point for ocean reanalyses, OSSEs etc.

-   NOS: Provide high-resolution regional ocean modeling for the USA
    (including the Great Lakes), integrated in the global ocean model
    from NCEP as downstream models on NCEP computing platforms.

    -   Provide boundary data for coastal products for NOS and for
        downstream users.

    -   Provide regional data for (downstream) ecosystems models.

    -   Provide an integrating environment for IOOS-RA activities.

    -   Provide a starting point for regional reanalyses, OSSEs etc.

-   IOOS, NOAA-IOOS (OAR?): Promote and provide input to the above
    modeling backbone activities of NWS and NOS. Provide a vehicle to
    integrate these activities with the modeling community at large.

    -   Promote community participation with, and integration in, a NOAA
        / national modeling backbone capability.

    -   Direct available funding to promote unified backbone
        capabilities and to avoid the development of 'stovepipe"
        approaches. Note that this does not imply that model diversity
        should be suppressed, but that a modeling framework should be
        promoted.

-   NCEP, NODC, NCDC, NCDDC: Provide a data portal of real-time and
    historical model data to the general public, and a clearinghouse for
    modeling data within NOAA and for downstream model users.

> Note that ecosystems modeling is not explicitly mentioned in the above
> view. A distinction should be made between two types of ecosystems
> model:

-   Models and processes that directly influence physical modeling and
    processes in the ocean, such as sediment transport and chlorophyll
    (particle) models. Such models need to be integrated with the
    physical ocean models and will require a close cooperation between
    NWS, NOS and developers of such ecosystems models.

-   Models that can be considered as downstream users of physical ocean
    models such as fish stock assessments. Such models rely heavily on
    efficient data clearing houses, and therefore would require a close
    cooperation between NMFS and NODC, with appropriate physical model
    parameters being provided by NWS and NOS.

2)  Funding:

> There is presently a discrepancy between the direction given to and
> accepted by NOAA from the SAB report, and the funding allocated by
> NOAA to follow these directions. Three separate targets for\] funding
> are relevant in this context:

a)  Human resources:

> Stable funding is required to develop and maintain in-house expertise.
> Stability of funding is critical for funding transition form research
> and development to operations.

b)  Computational resources:

> Moving forward to an integrated Earth Modeling System requires
> modeling on a central platform, tentatively NCEP's operational
> computing. NCEP computing should be expanded according to the new
> modeling requirements with a corresponding increase in funding for
> computer resources.

c)  Data storage and dissemination:

> For a modeling effort to become a true (element of) a national
> backbone, data access and dissemination of data to a broad range of
> users will be critical and should be designed and funded
> appropriately.
>
> The success of this mission depends upon a well balanced allocation of
> resources for each of these targets.
>
> Note 1: There are acute funding issues with ocean modeling
> particularly at NCEP. The operational HYCOM implementation at NCEP has
> been implemented thanks to NOPP funding. This funding runs out during
> FY 2008. No NOAA funding has been allocated to support HYCOM in
> operations. Without continued funding there is a danger that the
> developed in-house expertise will evaporate, and that NCEP's effort
> will have to start its ocean modeling effort anew once consistent
> funding becomes available.
>
> NOS has a minimal amount of base funding to support Operational
> Forecast Systems at CO-OPS but this is woefully short and creates a
> bottleneck for increased coverage. Some base funding is also available
> for development and transition at CSDL but it is critically
> underfunded to address development of regional and ecological models.
>
> Note 2: The development of physical and ecosystem modeling backbone at
> NOAA is an integral part of an integrated ocean observing system. IOOS
> in general and the NOAA IOOS Program Office in particular need to
> acknowledge this and consider funding accordingly. As a major
> downstream user of such a modeling effort the NMFS could also be
> approached and be justified to support this effort with R&D funding.
> The NMFS already supports extramural fish modeling R&D and these
> efforts need to be coordinated in the context of the NOAA ocean
> modeling backbone endeavor.

[^1]: Note that responsibility for climate scale modeling within NOAA
    resides with GFDL.