report to wgomd on gfdl ocean modelling activities 2004-2005
DESCRIPTION
Report to WGOMD on GFDL Ocean Modelling Activities 2004-2005. Stephen Griffies NOAA/GFDL (and CSIRO). IPCC AR4 activities Model developments. IPCC activities. Completed development of AR4 coupled climate model in 2004, and submitted simulations to PCMDI 2004/2005. - PowerPoint PPT PresentationTRANSCRIPT
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Report to WGOMD on GFDL Ocean Modelling Activities 2004-2005
Stephen Griffies
NOAA/GFDL (and CSIRO)
•IPCC AR4 activities•Model developments
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IPCC activities• Completed development of AR4 coupled
climate model in 2004, and submitted simulations to PCMDI 2004/2005.
• ~1 degree ocean (mom4) with 50 levels and 1/3 degree at equator. Described at previous meetings.
• Numerous studies now being conducted to document the model’s design and simulation characteristics. Will take years to fully evaluate.
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GFDL Coupled Model results
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References
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Ocean Model
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Plans for GFDL ocean model developmentA briefing to WGOMD
• Inform WGOMD of plans for MOM4 over next 6 months•Speculate on 3-5 years research/development goals and applications involving ocean models.
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MOM4 as of November 2005
• Four public releasesMOM4p0a Jan2004MOM4p0b Mar2004MOM4p0c Oct2004MOM4p0d May2005
• Roughly 300 registered users from 30 countries using ~35 computational platforms. They represent about 1200 scientists, engineers, and programmers using the code and simulation results for research and development.
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MOM4 user statistics
Vertical linesare intermediate code releases:mom4p0amom4p0bmom4p0cmom4p0d
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GFDL Applications of MOM4• IPCC Global climate change modelling:
– Ocean component to the GFDL AR4 climate change models. – Developed largely for global climate modeling applications.– ~50 GFDL scientists directly involved with this research and
development.• Earth system modelling:
– interactive land, atmosphere, ocean biogeochemistry and ecosystems
– ~30 scientists at GFDL and Princeton University• Global and regional process studies:
– paleo-oceanography– idealized climate change simulations– thermohaline shutdown– physical process studies – ~20 scientists, visiting researchers, post-docs, graduate
students
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Gravity current-entrainment CPT
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Eddy mixed layer interactions CPT
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MOM4p1: vertical coordinate features)/()( Hz )/()(* HzHz
•Partial step topography•Trivial pressure gradient errors•Decades of experience•Well known limitations•Irregular and variable computational domain(i.e., land/sea masks and vanishing surface layer)
free surface z-model: mom4p0
•Terrain following σ-model•Smooth topography•Regular computational domain (no land/sea masks)•Time independent computational domain (-1 < sigma < 0)•Pressure gradient errors: requires topography filters•Difficult neutral physics implementation: not commonly done in sigma-models
•Irregular computational domain(i.e., land/sea masks needed)•Time independent computationaldomain (-H < z* < 0): no vanishing layers. •Negligible pressure gradient errors since isosurfaces are quasi-horizontal. Correspondingly, can use the same neutral physics technology as in z-models.
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Evolution of GFDL ocean codes Evolution is in response to many inputs
– New applications: • Refined resolution climate models• Biogeochemistry and ecosystem applications• Earth system modeling• Coastal impacts of climate change• Non-hydrostatic processes at very refined resolutions
– Enhanced features:• physical parameterizations (e.g., mixed layers, mesoscale eddies)• algorithm fundamentals (e.g., time stepping, vertical coordinates) • better understanding of the ocean (e.g., equation formulations)
– Computational efficiency and platform portability– Input from the international user communities (HIM, MITgcm, MOM4)
Main developers: Alistair Adcroft, Bob Hallberg, Steve Griffies
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Evolution Path
• MOM4p1: ~March 2006 with rudimentary generalized vertical coordinate features to expand mom4 applications.
• HIM-Fortran: Hallberg Isopycnal Model, publicly supported within GFDL Flexible Modeling System (FMS); GFDL development now aimed at coupled simulations to compare w/ mom4-based coupled model.
• Research: Merge three fundamental perspectives – non-hydrostatic z-modeling from MIT (Adcroft)– hydrostatic isopycnal modeling from HIM (Hallberg)– Global ocean climate modeling from MOM4 (Griffies)
• Key NOAA application: climate impacts on coasts– Global “BackBone Model” ~10 km with nest to ~1 km– Tides, wave breaking, storm surge, sediment transport, etc.
• ~2008-2010 for first public code release
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Horizontal grids: nesting and cubed sphere• Multiple 2-way nested regions• Mass and tracer conservation: Most nesting implementations in ocean and
atmospheric models are non-conservative• Time sub-cycling: coarse region not constrained by time step used in fine
region. Essential for economical global models with nests. • Envision applications in areas such as
– global climate models: boundaries, choke points, etc. – Regional modeling with nests to estuary scale– Coastal biogeochemistry and ecosystems
• Present development– general grid description– tools for parallel computing and coupled modeling– analysis/visualization tools – shallow water test cases
• Cubed Sphere – technology from MITgcm– Also envisioned for finite volume atmosphere model
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Main Applications
• Coastal impacts of climate change• Earth System Modelling w/ eddying
simulations (~1/3 to 1/4 degree mercator with twoway nesting in selected critical regions)
• NOAA “BackBone” model, with ~1/10 global to be nested with finer grids in certain coastal areas. For use by many projects within NOAA.
• nonHydrostatic process studies and very refined coastal and estuary simulations
• University PI and student research and education
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HYDROSTATIC
NON-HYDROSTATIC
~100 km~10 km~1 km
~20 m ~100 m
~1000 km
HIM + MIT + MOM = ???
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Unified GFDL Ocean Code• Bring together our understanding of the ocean and how
to simulate a wide range of scales. • Various algorithms with stepwise evolution involving
suites of applications to test methods and flesh out favourable approaches.
• This effort is a major research and development project, presently in its early stages at GFDL. Much research remains to determine particulars of algorithms.
• Various efforts (e.g., HOME) to develop a US community model have failed to garner funds. GFDL is committed to this project using in-house resources, and will involve outside collaborators as best as possible.