A Community Terrain-following Ocean Modeling System

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A Community Terrain-following
Ocean Modeling System
Hernan G. Arango, Rutgers University
(arango_at_imcs.rutgers.edu)
Tal Ezer, Pricenton University
(ezer_at_splash.princeton.edu)
FTP
File TOMS.tar
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COLLABORATORS

• Bennett et al. (FNMOC OSU)
• Chassignet / Iskandarani et al. (RSMAS)
• Cornuelle / Miller (SIO)
• Geyer (WHOI)
• Hetland (TAMU)
• Lermusiaux (Harvard)
• Mellor (Pricenton)
• Moore (U. Colorado)
• Shchepetkin (UCLA)
• Signell (SACLANT USGS)

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OTHER COLLABORATORS

• Chao / Song (JPL)
• Preller / Martin (NRL)
• Naval Operational Community
• POM Ocean Modeling Community
• ROMS / SCRUM Ocean Modeling Community

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OBJECTIVES

• To design, develop and test an expert ocean
  modeling system for scientific and operational
  applications
• To support advanced data assimilation strategies
• To provide a platform for coupling with
  operational atmospheric models (like COAMPS)
• To support massive parallel computations
• To provide a common set of options for all
  coastal developers with a goal of defining an
  optimum coastal/relocatable model for the navy

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APPROACH

• Use state-of-the-art advances in numerical
  techniques, subgrid-scale parameterizations,
  data assimilation, nesting, computational
  performance and parallelization
• Modular design with ROMS as a prototype
• Test and evaluate the computational kernel and
  various algorithms and parameterizations
• Build a suite of test cases and application
  databases
• Provide a web-based support to the user community
  and a linkage to primary developers

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CHALLENGE
The complexity of physics, numerics, data
assimilation, and hardware technology should be
transparent to the expert and non-expert USER
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TOMS KERNEL ATTRIBUTES

• Free-surface, hydrostatic, primitive equation
  model
• Generalized, terrain-following vertical
  coordinates
• Boundary-fitted, orthogonal curvilinear,
  horizontal coordinates on an Arakawa C-grid
• Non-homogeneous time-stepping algorithm
• Accurate discretization of the baroclinic
  pressure gradient term
• High-order advection schemes
• Continuous, monotonic reconstruction of vertical
  gradients to maintain high-order accuracy

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Dispersive Properties of Advection
5/2
Parabolic Splines
2
10
Vs Finite Centered Differences
6
3/2
8
K(k) ?x
4
1
2
1/2
?/4
3?/4
?/2
k?x
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TOMS SUBGRID-SCALE PARAMETERIZATION

• Horizontal mixing of tracers along level,
  geopotential, isopycnic surfaces
• Transverse, isotropic stress tensor for momentum
• Local, Mellor-Yamada, level 2.5, closure scheme
• Non-local, K-profile, surface and bottom closure
  scheme

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TOMS BOUNDARY LAYERS

• Air-Sea interaction boundary layer from COARE
  (Fairall et al., 1996)
• Oceanic surface boundary layer (KPP Large et
  al., 1994)
• Oceanic bottom boundary layer (inverted KPP
  Durski et al., 2001)

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TOMS BOUNDARY LAYERS

• Air-Sea interaction boundary layer from COARE
  (Fairall et al., 1996)
• Oceanic surface boundary layer (KPP Large et
  al., 1994)
• Oceanic bottom boundary layer (inverted KPP
  Durski et al., 2001)

• Wave / Current / Sediment bed boundary layer
  (Styles and Glenn, 2000)
• Sediment transport

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TOMS MODULES

• Lagrangian Drifters (Klinck, Hadfield)
• Tidal Forcing (Hetland, Signell)

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Gulf of Maine M2 Tides

Surface Elevation (m)
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TOMS MODULES

• Lagrangian Drifters (Klinck, Hadfield)
• Tidal Forcing (Hetland, Signell)

• River Runoff (Hetland, Signell, Geyer)

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Hudson River Estuary
30
-5
25
-10
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Salinity (PSS)
Depth (m)
-15
15
-20
10
-25
5
25
5
15
20
10
Distance (km)
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TOMS MODULES

• Lagrangian Drifters (Klinck, Hadfield)
• Tidal Forcing (Hetland, Signell)
• River Runoff (Hetland, Signell, Geyer)

• Biology Fasham-type Model (Moisan, Shchepetkin)
• EcoSim Bio-Optical Model (Bissett)

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TOMS TESTING

• Systematic evaluation of numerical algorithms via
  robust test problems
• Data/Model comparisons
• Study optimal combination of algorithmic options
  for various coastal applications
• Documentation of testing procedures

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TOMS CODE DESIGN

• Modular, efficient, and portable Fortran code
  (F77, F90)
• C-preprocessing managing
• Multiple levels of nesting
• Lateral boundary conditions options for closed,
  periodic, and radiation
• Arbitrary number of tracers (active and passive)
• Input and output NetCDF data structure
• Support for parallel execution on both shared-
  and distributed -memory architectures

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TOMS PARALLEL DESIGN

• Coarse-grained parallelization

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TOMS PARALLEL DESIGN

• Coarse-grained parallelization

• Shared-memory, compiler depend directives MAIN
  (OpenMP standard)
• Distributed-memory (MPI SMS)
• Optimized for cache-bound computers
• ZIG-ZAG cycling sequence of tile partitions
• Few synchronization points (around 6)
• Serial and Parallel I/O (via NetCDF)
• Efficiency 4-64 threads

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TOMS DATA ASSIMILATION

• Nudging
• Optimal Interpolation (OI)
• Tangent linear and Adjoint algorithms
• 4D VARiational data assimilation (4DVAR) and
  Physical Statistical Analysis System (PSAS)
  algorithms
• Inverse Ocean Modeling System (IOMS)
• Ensemble prediction platform based on singular
  value decomposition
• Error Subspace Statistical Estimation (ESSE)

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ESSE Flow Diagram
DE0/N

DP0/N
-
-

Most Probable Forecast

Synoptic Obs
A Posteriori Residules dr ()
Historical, Synoptic, Future in Situ/Remote
Field/Error Observations d0R0

-
-
Data Residuals
Measurement Error Covariance

d-CY(-)
Ensemble Mean



eqYj(-)
Gridded Residules

Y(-)

-


j1
Y()
Y()
Y1 Yj Yq

-
Y1 Yj Yq

0

-
E(-) P(-)

-
0



-
/-

E0 P0
0
jq
uj(o,Ip) with physical constraints
Continuous Time Model Errors Q(t)
Ea() Pa()

E() P()
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PRESSURE GRADIENT FORCE

• Density Jacobian Class (Blumberg and Mellor,
  1987 Song 1998 Song and Wright 1998)
• More Accurate
• Error vanishes with linear density profiles
• Pressure Jacobian Class (Lin 1998 Shchepetkin
  and McWilliams, 2001)
• JEBAR consistent
• Conserve Energy

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RESULTS (YEAR 1)

• Build TOMS from ROMS prototype
• Mellor-Yamada, level 2.5
• Passive and active open boundary conditions
• Tidal forcing
• River runoff
• Lagrangian drifters
• Data assimilation
• Inter-comparison between POM and ROMS
• Evaluation of time-stepping, advection, and
  pressure gradient algorithms
• Initial development of TOMS web site

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TRANSITION PATHS

• To Be Determined !!!
• Potential Users
• NAVO
• FNMOC
• NOAA
• USCG

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PUBLICATIONS

• Chassignet et al., 2000 Damee modeling review
• Ezer, 2000 Mixed-layer evaluation
• Ezer and Mellor, 2000 POM Damee application
• Haidvogel et al., 2000 ROMS Damee application
• Malanotte-Rizzoli et al., 2000 ROMS Damee
• Mellor, 2001 Improved turbulence scheme
• Mellor et al., 2001 Generalized vertical
  coordinate