180 likes | 309 Views
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.
E N D
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. • ~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.
Inform WGOMD of plans for MOM4 over next 6 months • Speculate on 3-5 years research/development goals and • applications involving ocean models. Plans for GFDL ocean model development A briefing to WGOMD
MOM4 as of November 2005 • Four public releases MOM4p0a Jan2004 MOM4p0b Mar2004 MOM4p0c Oct2004 MOM4p0d 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.
MOM4 user statistics Vertical lines are intermediate code releases: mom4p0a mom4p0b mom4p0c mom4p0d
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
MOM4p1: vertical coordinate features 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 • 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) • Irregular computational domain • (i.e., land/sea masks needed) • Time independent computational • domain (-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.
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
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
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
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
~1000 km ~100 km ~10 km ~1 km ~100 m HYDROSTATIC ~20 m NON-HYDROSTATIC HIM + MIT + MOM = ???
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.