ABSTRACTS
Using ROMS in the North Sea - a validation study
Bjørn Ådlandsvik
Institute of Marine Research, Bergen, Norway
The ROMS model is set up for a North Sea domain with 8 km
grid size. The meteorological forcing is taken from the NCEP
reanalysis. Laterally it is forced by climatology, tides, and
fresh water runoff. As this is a preliminary step in seting up a
nested system, the issue of open boundary conditions are examined.
The Flow Relaxation Scheme is implemented as an
open boundary condition for the 3D baroclinc mode in ROMS.
The performance of this scheme is compared with the alternative
boundary conditions.
The model results are compared to the extensive Skagex
dataset obtained in an international coordinated field experiment
in 1990. Emphasis is put on recreating the observed temperature
and salinity structure in the Skagerrak and the Norwegian
coastal areas.
Tuning of a Numerical Model (POM) for Study of Oceanic
Circulation along the Peruvian Coast.
Aguirre, E, E, L.; Campos, E. J. D.
Oceanographic Institute of São Paulo University
The model is tuning with the goal of studying the oceanic circulation
in the region of the Pacific Ocean along the Peruvian
coast. The turning process consist of three stages: Generation
of curvilinear grid with variable resolution, Interpolation of
bathymetry, climatological data of temperature and salinity
and wind stress of scatterometers ERS-1 and ERS-2 for points
of the curvilinear grid, and Realization of a preliminary experiment
of turning.
First, we get the grid of finite difference through the use of
GRIDPAK software. The resolution varies from near 100 Km
in the oceanic region to 10 Km in regions more near to the
coast. Then we get a bathymetric data used through ETOPO-2
(Earth Topography at 2 minutes resolution). The model ran for
more 50 days, the circulation pattern to the end of simulation
is still very indefinite, showing clearly that the model is still in
the process of baroclinic tuning.
In spite of that realistic simulation, we notice some interesting
characteristics such as the raising of isotherms in regions
nearest to the surface in the east of the grid (coastal upwelling)
and also a change in the inclination of isotherms with
depth. This fact suggests the change in a contrary direction of
a current near the slope (Cronwell Current).
A Terrain-Following Ocean Modeling System (TOMS)
Hernan G. Arango
Institute of Marine and Coastal Sciences, Rutgers University
An overview and status report of an ongoing effort to develop
the next generation terrain-following ocean model for scientific
and operational applications will be presented. The new
model was distributed to several beta testers last January and
to the full ROMS community at the end of June 2003. The
system includes accurate and efficient numerical algorithms, a
suite of vertical mixing schemes, interfaces for coupling
to atmospheric forecasting models, multiple levels of nesting
and composed grids, and tangent linear and adjoint models for
variational data assimilation (4DVAR, representers), ensemble
forecasting, and stability analysis. The parallel framework
includes both shared-memory (OpenMP) and distributedmemory
(MPI) paradigms.
Nowcast/Forcast System of Prince William Sound, Alaska
Inkweon Bang and Christopher N.K. Mooers
Ocean Prediction Experimental Laboratory (OPEL), RSMAS,
University of Miami
Nowcast/Forcast System of Prince William Sound, Alaska
(PWS-NFS) based on POM has been up and running since
November, 2000. Beginning March 2003, a high-resolution (4
km), regional atmospheric model (PWS-RAMS) has been
providing 36-hour forecast winds for PWS-NFS. A hydrological
model is also implemented which forecast freshwater flux
to PWS due to snowmelt in the surrounding mountains. These
two major additions along with tidal sub-component which is
already running makes PWS-NFS a failry comprehensive NF
system. A process study has been conducted for the interaction
of PWS with Northern Gulf of Alaska (Bang and Mooers,
2003. JPO, 33, 19-36) and a series of validation experiment
has also been performed (Bang and Mooers, 2003. CSR, under
revision).
A Coupled Ice-Ocean Model Based on ROMS/TOMS 2.0
W. Paul Budgell
Institute of Marine Research, Bergen, Norway
A dynamic-thermodynamic ice module has been developed for
coupling with ROMS 2.0. The ice dynamics are based upon
the Elastic-Viscous-Plastic rheology of Hunke and Dukowicz
(1997, 2002) and Hunke (2001). The thermodynamics are
based on those of Mellor and Kantha (1989) and Häkkinen
and Mellor (1992). The design and structure of the ice module
will be outlined. Preliminary results from the coupled model
will be presented from an application to a region consisting of
the Atlantic Ocean north of 30S, the GIN Seas and the Arctic
Ocean.
Sensitivity of the U.S. West Coast circulation to wind, heat
forcing and boundary conditions using a nested configuration
of ROMS.
X. Capet, P. Penven, J. McWilliams
IGPP/UCLA, IRD, IGPP/UCLA
Ocean dynamics along the U.S. West Coast (USWC) is largely
driven by a seasonally upwelling favorable wind stress which
generates a longshore coastal current, along with intense submeso-
and meso-scale features. Using ROMS, a realistic California
Current System (CCS) solution has been obtained and
has revealed nearshore sensitivity to the structure of the forcing
fields. This sensitivity is under investigation through the
use of increasingly high resolution and realistic products for
the wind, heat flux, and boundary conditions at the limits of
the regional domain. The cross-shore baroclinic structure of
the CCS long-term solutions is compared against corresponding
long term-data (essentially along CalCOFI line 67). More
generally, the effect and range of influence of localized forcing
changes on the CCS are assessed, using Eulerian and Lagrangian
diagnostics.
Uncertainty in Diagnostic Initialization
Chu, P.C., and A. Ong
Naval Postgraduate School
Ocean modeling is usually constrained by the lack of observed
velocity data for the initial condition. The diagnostic initialization
is widely used to generate velocity data as initial condition
for ocean modeling. It integrates the model from known
temperature (Tc), salinity (Sc) and zero velocity fields and
holds (Tc, Sc) unchanged. After a period of the diagnostic
run, the velocity field (Vc) is established, and (Tc, Sc, Vc)
fields are treated as the initial conditions for the numerical
modeling. During the diagnostic initialization period, the heat
and salt 'source/sink' terms are generated at each time step. In
this Thesis, the Princeton Ocean Model implemented to the
South China Sea demonstrated extremely strong thermohaline
sources and sinks generated by the diagnostic initialization.
Such extremely strong and spatially non-uniform initial heating/
cooling (salting/freshening) rates in the ocean model may
cause drastic change in thermohaline and velocity fields initially
(after the diagnostic run). There is a need to overcome
such problems or find alternative methods as diagnostic initialization
is extensively used.
Prediction-Skill Variability in Regional Ocean Models
Chu, P.C., and L.M. Ivanov
Naval Postgraduate School
Short and intermediate range (few days to two months) forecast
error evolution for a semi-enclosed ocean model is identified
using the model irreversible prediction time (IT). Model
prediction skill is examined with various input uncertainties
such as initial condition (IC) errors (first kind predictability),
wind errors, and boundary condition (BC) errors (second kind
predictability). Using the empirical orthogonal functions decomposition,
the Lyapunov dimension of the system attractor
is about 5.5 that in general indicates the exponential growth of
initial errors. However, our results demonstrate the existence
of a set of predictability regimes which are differ from the
traditional exponential error growth even for the first kind of
predictability. Initial error evolutes at least along fourth successive
dynamical regimes: (i) first error decay, (ii) exponential
and super-exponential growth (iii) power growth for and
(iv) saturation due to nonlinear effects. For stochastic wind
forcing and uncertainty of open boundary condition we also
observed altering regimes of exponential and power growth of
model error and its saturation. For two sources of uncertainty,
such as weakness initial errors and stochastic wind or open
boundary condition error, the decay of model error was found
as the first prediction regime. Statistics of IT were asymmetric
non-Gaussian even for infinitesimal and small errors, probability
density functions of IT have long tail stretching into
long and short prediction times. Excluding when initial error is
white noise there are always individual predictions called "extreme
successful predictions" which were considerably longer
that the mean or the most probable ones. Multi-attractor dynamical
system conception explains specificities of prediction
error behavior observed in the present study.
Hydrostatic correction for terrain-following ocean models
Chu, P.C. and C.W. Fan
Naval Postgraduate School
How to reduce the horizontal pressure gradient error is a key
issue in terrain-following coastal models. The horizontal pressure
gradient splits into two parts and incomplete cancellation
of the truncation errors of those parts cause the error. Use of
the finite volume discretization leads to a conserved scheme
for pressure gradient computation that has better truncation
properties with high accuracy. The analytical coastal topography
and seamount test cases are used to evaluate the new
scheme. The accuracy of the new scheme is comparable to the
sixth-order combined compact scheme (with an error reduction
by a factor of 70 comparing to the second-order scheme)
with mild topography and much better than the sixth-order
combined compact scheme with steep topography. The computational
efficiency of the new scheme is comparable to the
second-order difference scheme. The two characteristics, high-
accuracy and computational efficiency, make this scheme useful
for the sigma coordinate ocean models.
Modelling the Generation of Haida Eddies
Emanuele Di Lorenzo
Scripps Institution of Oceanography, La Jolla, California
Mike Foreman, Bill Crawford
Institute of Ocean Sciences, Sidney BC, Canada
A numerical model forced with average annual cycles of climatological
winds, surface heat flux, and temperature and
salinity along the open boundaries is used to demonstrate that
Haida Eddies are typically generated each winter off Cape St.
James, at the southern tip of the Queen Charlotte Islands of
western Canada. Annual cycles of sea surface elevation measured
at coastal tide gauges and TOPEX/POSEIDON crossover
locations are reproduced with reasonable accuracy. Model
sensitivity studies show that Haida Eddies are baroclinic in
nature and are generated by the merging of several smaller
eddies that have been formed to the west of Cape St. James.
The generation mechanism does not require the existence of
instability processes and is associated with the mean advection
of warmer and fresher water from Hecate Strait around the
cape. Sustained winds to the north or northwest (typical in
winter) are a necessary condition for this advection and strong
winds, such as those seen during the 1997-98 El Niño, have
produced eddies with diameters larger than 200km and lifetimes
longer than two years after they detach from the coast
and drift into the Gulf of Alaska.
On mixing and advection in the BBL and how they are
affected by the model grid: Sensitivity studies with
a generalized coordinate ocean model
Tal Ezer and George L. Mellor
Princeton University
An extension of a sigma coordinate ocean model that includes
a generalized coordinate system allows a comparison between
the behavior of bottom boundary layers (BBLs) in terrainfollowing
and in z-level vertical grids, while other numerical
aspects remain unchanged. Sensitivity studies with a course
resolution (100 km) basin-scale configuration and with a
higher resolution (10 km and 2.5 km) regional domain are
used to investigate the influence of model parameters such as
horizontal diffusivity, vertical mixing, horizontal resolution,
and vertical resolution on the simulation of bottom layers for
the different coordinate systems. A major difference in the
behavior of the BBL in the two grids is caused by a too large
vertical mixing generated by the second order turbulence
scheme over the step-like topography in the z-level grid, compared
to a weaker mixing and a more stably stratified BBL in
the sigma grid. Therefore, a better resolved BBL and more
realistic deep-water masses are achieved with terrainfollowing
grids, while z-level grids require additional special
BBL formulations to achieve acceptable results. Increasing
horizontal and vertical resolution in the z-level grid converges
the results toward those obtained by a much coarser resolution
sigma coordinate grid, but some differences remain due to the
basic differences in the mixing process in the BBL.
Regional Ocean (POM)/Atmosphere (MMS) Coupled
Modeling System for Brazilian Coast
M. R. Fragoso, R. M. Silva, Audalio R. Torres Jr.
Marine and Atmospheric Processes Modeling Laboratory
Federal University of Rio de Janeiro, Brazil
The marine circulation of southeast Brazilian coast presents
some interesting characteristics such as meanders and eddies
that occur in Brazil Current largely influenced by a complex
seabed topography, as well as ocean/atmosphere interaction
processes like upwelling and sea breeze, which makes its circulation
very complex. In order to try to capture most part of
the complexity of the marine dynamics of this region, a regional
ocean/atmosphere coupled model system (MOREA)
was designed by the Marine and Atmospheric Processes Modeling
Laboratory (LAMMA) of the Federal University of Rio
de Janeiro - Brazil. The MOREA system consists in coupling
the Princeton Ocean Model (POM) (using boundary and initial
conditions provided by the Modular Ocean Model - MOM)
with the PSU/NCAR Mesoscale Modeling System (MMS)
(using boundary and initial conditions provided by reanalyses
NCEP project). The MOREA system intends to be a diagnostic
and prognostic system of ocean and atmosphere, in regional
scale, of the southeast Brazilian coast. Strategy of coupling
and preliminary results will be shown and discussed.
High-Resolution Coastal Ocean Model and Application to
Coral Reef Ecosystems in Western Boundary Current
Jerome Fiechter and Christopher N.K. Mooers
RSMAS, University of Miami
The East Florida Shelf - Princeton Ocean Model (EFS-POM)
is implemented as part of the Southeast Atlantic - Coastal
Ocean Observing System (SEA-COOS) program. With a highresolution
of ca. 2-6km horizontally and 25 terrain-following
levels, the model is used to study the variability of the Florida
Current under synoptic atmospheric forcing for periods of
several years. Sea surface temperatures and coastal sea levels
are compared with observations from moored buoys and tide
gauges. EFS-POM also serves as a source for open boundary
conditions to drive a nested model of the Dry Tortugas domain.
With horizontal resolutions of less than 1km, this local
model is aimed at predicting the influence of physical variables
such as temperature, salinity and turbulence on coral reef
communities. In addition to the Eulerian fields, a Lagrangian
approach is used to investigate transient circulation patterns
and provide some insight about possible pathways and rates
for larval dispersion and recruitment at both local and regional
scales.
Open boundary condition for a limited-area coastal model
off Oregon
Jianping Gan and J. S. Allen
Oregon State University
Open boundary conditions (OBCs) developed for a limitedarea
high-resolution coastal ocean model off Oregon are discussed
in this study. The OBCs separate not only the inward
and outward fluxes, but also the local and the coastallytrapped
wave-related global solutions at the open boundaries.
The external information, which is provided by a reducedphysics
two-dimensional (x-z) model in this study, is smoothly
imposed into the model domain during inward flux. The disturbances
from the interior of the model are radiated out of the
domain by applying radiation boundary condition on the
global solutions during outflow conditions. To ensure consistancy,
the same OBCs are applied to both barotropic and baroclinic
variables. A weak spatial smoother is used in the global
part of the solution at the open boundary where long coastal
trapped waves exit to effectively eliminate noisy fluctuations.
The transition between inward and outward fluxes is coped
with using a weak relaxation process. A number of experiments
are conducted to examine the effects of OBCs on shelf
flow fields from different wind and outer forcing regimes. The
model response during 1999 to spatially variable forcing by
heat flux and wind stress obtained from a mesoscale atmospheric
model is presented.
Implementing ROMS in Fortran 90: a good thing?
Mark Hadfield
National Institute of Water and Atmospheric Research
ROMS 2 is written in Fortran 90, whereas ROMS 1 was written
in Fortran 77. The new version makes use of some of the
new features in Fortran 90 (eg. composite data types, dynamic
memory allocation) but not of others (eg. operations on array
subsets). As a result, performance appears not to have suffered
and in some situations has improved. At NIWA, ROMS has
been run on single-processor workstations and on a distributed-
memory supercomputer (Cray T3E). I will discuss its
performance on these platforms, point out some pitfalls and
draw some general lessons for implementing ocean hydrodynamics
codes in Fortran 90.
NZ Region Ocean Modelling with Terrain-Following
and Z-Level Models
Mark Hadfield and Graham Rickard
National Institute of Water and Atmospheric Research
We have attempted to capture the mean circulation in the vicinity
of New Zealand on a domain covering some 50 degrees
latitude by 40 degrees longitude. Flow in this domain is controlled
by the interaction of global and basin-scale currents
(notably the Antarctic Circumpolar Current and the South Pacific
western boundary current) with the topography of the
New Zealand land mass. Simulations with a z-level model,
MOMA, have been reasonably successful in matching observations.
Simulations with a terrain-following model, ROMS,
have been less successful. We find that ROMS is affected by a
tendency observed in other terrain-following models: it supports
vertically coherent, bathymetrically locked currents. This
has unfortunate consequences for the flow around the eastern
edge of the land mass. The presentation will describe the problem
and discuss attempts to resolve it.
NASA POM Performance Optimization: Costs and Benefits
of using MPI, SMS and OpenMP
Sirpa Hakkinen, Jelena Marshak
Goddard Space Flight Center, NASA
NASA version of POM represents Coupled Ice-Ocean Model.
POM was developed in late 1970 by G. Mellor and A. Blumberg;
in 1990, Ice Model functionality was added to the POM
by S. Hakkinen, who continues to enhance and use the Coupled
Model for Arctic-North Atlantic climate modeling. As the
computing technology advances it offers ways to optimize the
performance of NASA POM, which was recently ported from
Cray SV1 and Cray T3E machines to Compaq CS45. In an
attempt to find the best way to decrease the execution time,
several optimization techniques were applied to the model
code, including MPI, SMS and OpenMP. Each of them has
their own benefits and disadvantages. The presented poster
will compare and analyze the techniques based on their application
to the Ice-Ocean Model.
Test Problems and FVCOM
Kate Hedstrom
University of Alaska Fairbanks, ARSC
The Finite Volume Coastal Ocean Model (FVCOM, Chen et
al.) is a new sigma coordinate model, using unstructured, triangular
grids. We are considering its use in the Gulf of Alaska
due to the nature of the coastline there. Before trying any
model in a realistic environment, the logical thing to do is to
try it on some test problems. This allows us to learn about its
numerical characteristics in a controlled environment and allows
us to learn the model in a relatively small domain. I will
present the results of FVCOM with several of the Haidvogel
and Beckmann test problems.
HPC and the ROMS benchmark Problem
Kate Hedstrom
University of Alaska Fairbanks, ARSC
The Arctic Region Supercomputing Center is in the process of
acquiring two new supercomputers. Other groups are also considering
new equipment so we felt that creating a BENCHMARK
application for comparing these systems would be a
good idea. Our experiences with this problem on the ARSC
computers will be described, as will the computers themselves.
The influence of tides on the sub-Amery Ice Shelf
thermohaline circulation.
Mark Hemer, John Hunter
Antarctic Co-operative Research Centre, University of
Tasmania
A modified version of the free-surface Princeton Ocean
Model is applied to the ocean cavity beneath the Amery Ice
Shelf, East Antarctica, with tides included in the dynamics.
The mean density driven circulation beneath the ice shelf
is characterised by a buoyancy driven overturning circulation
caused by melting and freezing at the base of the ice shelf parameterised
in the model with surface heat, salt and mass
fluxes.
The effects of increased mixing as a result of tidal forcing
at the open boundaries will be presented - both on the predicted
mass balance of the ice shelf, and on the mean sub-iceshelf
circulation.
The influence of global warming on the melting and freezing
rates in the sub-ice-shelf cavity, and its dependence on
tides, will also be discussed.
Numerical Simulation of Tides in the Northern South
China Sea and its Adjacent Seas
Jianyu Hu, Hiroshi Kawamura
Institute of Subtropical Oceanography, Xiamen University,China;
Center for Atmospheric and Oceanic Studies, Tohoku University, Japan
Princeton Ocean Model (POM) has been used to simulate the
tides in the northern South China Sea and its adjacent seas.
The model has a horizontal grid spacing of 1/12deg in longitude
× 1/12deg in latitude (about 9.26 km) and is applied to
the studied area between 105.5E-128.5E and 15.0N-30.0N. It
is simultaneously forced by seven principal tidal constituents
(M2, S2, K1, O1, P1, N2 and K2) at the east, south and north
open boundaries. The harmonic constant of each considered
tidal constituent at the open boundary is obtained using the
tidal harmonic constants derived from 6 years of
TOPEX/POSEIDON altimeter data from 1993 to 1999. The
simulated results in a barotropical state indicate that the cotidal
charts of all these principal tidal constituents are in good
agreement with those derived from satellite altimeter data and
in situ observations. Finally, several problems encountered
with the baroclinic tidal simulation are discussed.
Sensitivity of the Equatorial Undercurrent to the vertical
mixing parameterization
Takashi Kagimoto
Frontier Research System for Global Change, Japan.
How the Equatorial Undercurrent (EUC) is spun up in the numerical
model is examined with various kinds of vertical mixing
parameterizations. The Princeton Ocean Model with the
modified turbulent closure model (Mellor, 2001) could not
represent the EUC well. Maximum zonal velocity of the simulated
EUC is at most 20cm/sec and its spatial structure is very
far from the real one. This is due to the upper bound for the
non-dimensional shear function (GM). When the vertical shear
increases, the turbulent kinetic energy also increases because
of the upper bound. This leads to the large vertical eddy viscosity
and tends to destroy the vertical shear between the
South Equatorial Current and the EUC. This is not the case
with the original Mellor-Yamada 2.5 turbulent closure model.
In fact, it does not have such the upper bound for the GM
function.
Inter-annual variability of circulation and water mass
properties in the Yellow Sea using ROMS
Chang S. Kim and H.S. Lim
Korea Ocean R&D Institute
Digital Ocean and Virtual Environment Center
The Yellow Sea is characterized by relatively shallow water
depth, varying range of tidal action and very complex coastal
geometry such as islands, bays, peninsulas, tidal flats, shoals
etc. The dynamic system is controlled by tides, regional
winds, river discharge, and interaction with the Kuroshio. The
circulation, water mass properties and their variability in the
Yellow Sea are very complicated and still far from clear understanding.
Numerical simulation of using the ROMS model was conducted
for seasonal circulation and thermohaline structure in
the Yellow Sea. This study demonstrates the applicability of
the terrain-following ROMS model to major processes in the
Yellow Sea such as distinct features of different circulation
patterns, dilution of seawater due to fresh water discharge
from major rivers, exchange between coastal waters and shelf
waters across the tidal fronts etc.
The model adopts curvilinear grid with horizontal resolution
of 3 -5 km and 20 vertical grid spacing confirming to relatively
realistic bottom topography. The model was initialized
with the LEVITUS annual climatological data and forced by
the monthly mean air-sea fluxes of momentum, heat and fresh
water derived from COADS. On the open boundaries, climatological
temperature and salinity are nudged every 5 days for
data assimilation. During the simulation run after the initial
run, the model was integrated again for another several more
years with climatological monthly mean surface wind stress,
net heat flux, and fresh-water flux from the COADS data and
available regional environmental data.
This study demonstrates a Yellow Sea version of Atlantic
Basin experiment conducted by Haidvogel et al. (2000) experiment
that the ROMS simulates the dynamic variability of
temperature, salinity, and velocity fields in the ocean.
Modeling the Denmark Strait Overflow
Frank Koesters, Rolf Kaese
Institute for Geosciences, Institute for Marine Research
University of Kiel
The Denmark Strait plays an important role as a dense water
gateway from the Arctic to the North Atlantic. Previous studies
have shown that the volume transported over the sill is
limited by hydraulic constraints. A regional ocean circulation
model (ROMS) with a horizontal resolution of 1/20 degree
and 30 sigma levels in the vertical is applied to study presentday
throughflow characteristics. First, a process model is used
changing the upstream reservoir conditions systematically to
test hydraulic limitations. Generally, the throughflow is less
than the predicted maximal value from hydraulic theory by
almost 50%. Second, the process model is extended to realistic
climatology and surface forcing. Model results indicate only a
weak influence of the vertical stratification on the overflow
but changes in entrainment and overflow path. Moreover, direct
influence of wind seems to be minor. The results will be
compared to observations and an initial open-boundary version
of the model.
Computing Issues for Modelers: The Synergy between
Computer Science and CFD
Dov Kruger, Anne Pence and Alan Blumberg
Davidson Laboratory, Stevens Institute of Technology
CFD Modelers are dependent on computers, so it is little surprise
that computer science knowledge can have a beneficial
effect on modeling. We present an overview on: (1)hardware
characteristics (using the PC architecture as an example),(
2)price/performance ratio of various computing solutions,
(3)single-CPU optimization techniques and heuristics,
(4) shared memory parallelization (automatic and OpenMP),
and (5) MPI.
The second part focuses on optimization and accuracy and
how computer science and CFD modeling each hold promise
at improving the state of the art of the other discipline. We
first try to debunk scientists' generally optimistic view of what
compilers will and will not optimize. We show that a computer-
science focus enables us to manually speed the core algorithms
in ECOMSED /POM by a factor of 3 to 7, and eventually,
we hope roughly a factor of 5 overall. Getting an immediate
performance jump by a factor of two or three is relatively
easy; further optimizations are quite difficult and make
the code increasingly difficult to understand. We then propose
automated tools to solve this need. In the course of these experiments,
we have incorporated the the knowledge of CFD
modelers to define a new set of optimizations that will dramatically
enhance performance of next-generation models
without requiring the laborious hand optimizations that are
currently needed. Examples include a sample 20-fold improvement
in computational speed of bottom shear, a high
speed implementation for calculation of density.
Last, we discuss computational accuracy, and point out
inconsistencies in the current models; some routines are computed
very accurately even though the accuracy is discarded
immediately afterward. We point out solutions, and point out
that a more coherent strategy is needed to validate models and
prevent potential problems.
Assimilation of moored ADP currents into a model of
coastal wind-driven circulation off Oregon
Alexander L. Kurapov , J. S. Allen, G. D. Egbert, R. N. Miller
COAS/ Oregon State University
A system based on the Princeton Ocean Model and an optimal
interpolation (OI) sequential data assimilation (DA) algorithm
is utilized to assimilate low-pass filtered velocity measurements
from an array of moored Acoustic Doppler Profilers
(ADP) installed off Oregon during the COAST (Coastal Advances
in Shelf Transport) field experiment, May-August
2001. An inhomogeneous stationary estimate of the forecast
error covariance, required for OI, was obtained from averaging
over an ensemble of model solutions. Our objectives include
determination of the alongshore spatial scales of influence
of assimilated currents and examination of multivariate
capabilities of the data assimilation system. Different data sets
from the COAST field experiment are used for model validation.
We find that DA improves prediction of the currents at
an alongshore distance of 90 km from the site where data were
assimilated, both to the north and to the south. Improvement to
the south in part results from advection of corrections with the
southward upwelling jet. Improvement to the north may be an
effect of northward propagation of information with coastally
trapped waves. Assimilation of moored ADP velocities improves
modeled sea surface height near the coast and isopycnal
structure in the interior. Discussion of solutions constrained
by the data includes analysis of a cross-shelf transport
and of dynamical processes responsible for biological productivity
on the mid-Oregon shelf, for instance, spatial and temporal
variability in bottom boundary layer processes.
A three-dimensional variational data assimilation system
for ROMS
Zhijin Li and Yi Chao
Jet Propulsion Laboratory
James McWilliams
University of California, Los Angeles
A real-time three-dimensional variational data assimilation
system (3DVAR) has been developed for ROMS, and implemented
in a real-time forecasting system for the U. S. West
coastal region. This 3DVAR system assimilates sea surface
temperatures (SSTs)and along track sea surface heights
(SSHs) from multiple satellites, as well as a variety of in-situ
measurements. The real-time implementation of this 3DVAR
has shown satisfactory performance in terms of results, reliability
and efficency.
Some particular strategies are implemented in this
3DVAR. A new strategy for constructing three-dimensional
error self-covariances and cross-covariance is developed,
which allows us to construct inhomogeneous and anisotropic
error correlations. To guarantee assimilated currents to be well
in dynamic balances, the 3DVAR is further implemented with
constraints in geostrophic and hydrostatic balances that are
applied to the analysis increment. This 3DVAR system has
been programmed with both OpenMP and MPI parallelism.
The limited-memory quasi Newton minimization algorithm
that has been recognized to be the most efficient algorithm for
atmospheric and oceanic data assimilation is employed.
Development of a multi-level parallel adaptive ROMS
John Z. Lou, Yi Chao, Zhijin Li
JPL/Caltech
We describe a framework of performing multi-level parallel
computations in the ROMS model, and an implementation of
the framework with the help of a parallel adaptive mesh library
called PARAMESH in a Fortran 90 environment. Topics
to be discussed include assumptions on concurrent multi-level
ROMS, adaptive mesh generation in a block-tree (PARAMESH)
framework, tools needed and issues for multi-level
computing and coupling, and load-balancing. A test case of
ROMS US West model under this framework will also be discussed.
On a New Version of Breaking Wave Parameterization
and Its Use in Ocean Circulation-Wave Coupling
Le Ly
Dept. of Oceanography, NPS, Monterey, CA 93943
Alexander Benilov
Davidson Lab, Stevens Institute of Technology, NJ 07030
Mary Batteen
Dept. of Oceanography, NPS, Monterey, CA 93943
Breaking waves are considered an important source of turbulent
energy, in addition to traditional shear production in the
air-sea system at all scales. Breaking waves also play an important
role in the development of thermo-dynamical and turbulent
structures in the ocean. Based on a new concept of oceanic
turbulence and a wave-breaking model, a surface wave
parameterization is developed. This wave parameterization
with wave-dependent roughness is compared with available
data on wave-dependent turbulence dissipation, roughness
length, drag coefficient, and momentum fluxes using a coupled
air-wave-sea model.
Taking the wind-wave-turbulence-current relationship into
account, a turbulence closure with the wave parameterization
is used in the POM model to create the NAval postgraduate
school ocean Model (NAM). The wave parameterization in the
model is able to relate model variables to wave parameters
such as wave height, age, phase speed, period, and length. The
NAM box model is used in an ocean circulation-wave coupling
study with idealized wave height and wave age fields for
the idealized California Coast region. This study is focused on
the sensitivity of the current field to the surface waves. The
study also demonstrates the capability of the NAM model to
reproduce an observed upwelling feature for the California
Coast region.
A Physical-Biological Model Coupling Study of the
West Florida Shelf
Le Ly (1,2)
National Ocean Service, NOAA
Dept. of Oceanography, Naval Postgrad School
Richard Stumpf, Thomas Gross and Frank Aiman III
National Ocean Service, NOAA
Studies have shown that harmful algae blooms (HAB) of
Karenia Brevis routinely occur along the West Florida Shelf in
late summer and can persist for months. These blooms can
impact commercial and recreational fisheries and the tourist
industry through inducing neurotoxin shellfish poisoning. An
effort to monitor and forecast these blooms has been ongoing
by NOAA for the past several years. A physical-biological
coupled model is used for the West Florida Shelf (WFS) in
which the Regional Ocean Modeling System (U.C. Berkeley
version) is coupled with a biological model of four components,
NPZD (Nutrient, Phytoplankton, Zooplankton and Detritus).
The WFS model is set up with realistic bathymetry,
temperature, salinity and wind forcing and numerical experiments
are carried out to study the model physical-biological
interaction under wind and stratification conditions that existed
during the late summers and autumns of 2000 and 2001.
The model results are compared with available data and discussed.
An Asymptotic Theory for the Interaction of Waves and
Currents in Shallow Coastal Waters
James C. McWilliams, UCLA
The scientific study of oceanic surface gravity waves is a mature
topic, operational implementation of WAM-type assimilation
and forecast models (Komen, 1994). The topic of wave
effects on oceanic currents is much less mature. From the perspective
of the wave community, the waves provide an averaged
radiation stress tensor, T, whose divergence accelerates
currents, at the shoreline (Longuet-Higgins & Stewart, 1964;
Longuet-Higgins, 1970; Hasselmann,1971) in addition to the
extra local mixing due to wave breaking. This approach has
had conspicuous success in predicting nearshore currents that
result from wave dissipation in the surfzone. However, this
viewpoint, while formally correct, usually does not capture the
principal wave effects when the output of a WAM-type model
is used to evaluate T. The more generally useful perspective
comes from the type of asymptotic-expansion and waveaveraging
theory first made by Craik & Leibovich (1976).
This implicates a wave-averaged vortex force, Us x (
x v)
- where Us is the waves' Stokes drift and v is the current velocity
- that has had great success as the basis for understanding
and simulating Langmuir Circulations and their material
transport in the surface boundary layer (McWilliams, 1997).
This type of theory was extended to include corrections to the
mean Ekman currents, Stokes-drift Lagrangian transport of
material concentrations, and wave modification of the inference
of surface geostrophic pressure from sea level measurements
(e.g., altimetry), all of which have been empirically
estimated as significant (McWilliams & Restrepo, 1999) but
which still lack direct observational testing.
Recently a further generalization to average over the approximately
100 m horizontal scale of the wave spectrum
peak, adds even greater structure to the predicted waveaveraged
dynamical effects on strong (e.g., coastal) currents
and associated material distributions(McWilliams, 2003). In it
a multi-scale asymptotic theory is derived for the evolution
and interaction of surface gravity waves and currents in water
of finite depth, under conditions typical of coastal shelf waters.
The practical utility of the theory is that it provides a
model with which shelf dynamics may be explored without the
necessity of resolving features of the flow on space and time
scales of the primary gravity-wave oscillations. The essential
nature of the dynamical interaction is currents modulating the
slowly evolving phase of the wave field and waves providing
both phase-averaged forcing of long surface waves and vortex
forces for the current evolution equations. Analogous relations
are derived for material tracers and density stratification which
include phase-averaged Stokes-drift advection. Illustrative
solutions are analyzed for the special case of depthindependent
currents. Prospects are discussed for its implementation
in ROMS and application to realistic coastal phenomena.
Recent and proposed modifications to turbulent mixing
in ocean models
George L. Mellor
Atmospheric and Oceanic Sciences, Princeton University
The talk will review three areas of recent research aimed at
improving turbulent mixing in ocean models:
1. The paper by Mellor (2002) parameterized the effects of
wave induced oscillations on bottom friction by the addition of
production to the TKE equation and by modifying the law-ofthe-
wall appropriately. It was then found (Newberger, personal
communication) that the parameterization became ineffectual
for poor bottom vertical resolution relative to the scale
of the bottom boundary layer. Very recently, this problem has
been significantly alleviated.
2. The wave breaking scheme of Craig and Banner (1994)
has been inserted into the Mellor-Yamada turbulence closure
model along with consideration of wave induced enhancement
of the surface drag coefficient (Mellor and Blumberg, 2003).
Mixing is enhanced during the summer months when the surface
boundary layer is shallow.
3. A new formulation to provide coupling between ocean
circulation models and wave models has been derived, exposing
fundamental unknowns and suggesting the need for new
research (Mellor, 2003).
Craig, P. D. and M. L. Banner, 1994: Modeling waveenhanced
turbulence in the ocean surface layer. J. Phys.
Oceanogr., 24, 2546-2559.
Mellor, G. L., 2002: The oscillatory bottom boundary
layer. J. Phys. Oceanogr., 32, 3075-3088.
Mellor, G. L. and A. Blumberg, 2003: Wave breaking and
surface layer thermal response. Submitted to J. Phys.
Oceanogr.
Mellor, G. L., 2003: The three dimensional, current and
surface wave equations. J. Phys. Oceanogr., In Press.
Advection-Confusion Revisited
Julie Pietrzak, David Ham and Guus Stelling
Delft University of Technology, The Netherlands
A novel unstructured grid semi-implicit finite volume ocean
model is presented. The model solves the three-dimensional
hydrostatic primitive equations. Typically coastal and oceanic
models employ horizontal orthogonal curvilinear co-ordinates
in order to resolve lateral boundaries and bathymetric features.
Unfortunately this approach lacks flexibility in modelling irregular
coastlines and bathymetry. However, complex
bathymetry needs to be resolved in order to compute details of
transport pathways in oceanic and coastal basins. In addition
coastal and boundary flows are dominated by alongshore
flows in approximate geostrophic balance. For such flows it is
important to ensure that the cross-shore region within a
Rossby radius of the coast is well resolved. At the same time it
is important to resolve the details of the coastline variability
and bathymetry, since these too have an important influence
on the alongshore propagation of waves and on coastal transport
processes in general. Therefore an unstructured model
approach was adopted here. Mass conservation was considered
an important property consequently a finite volume technique
was employed. The North Sea has a complex topography
including a deep trench in the north and shallow and variable
topography in the south. In addition it has complex lateral
boundaries that need to be resolved. Here examples of Kelvin
wave propagation in the North Sea are considered in order to
demonstrate the advantages of horizontal grid flexibility offered
by the unstructured approach.
Simulation of Southern Indian Ocean Using
Sigma Coordinate Ocean Model
Shailendra Rai, A. C. Pandey and A.P. Mishra
Banerjee Centre of Atmospheric & Ocean Studies, Allahabd
University
A sigma coordinate, free surface numerical model with turbulance
has been implemented for Southern Indian Ocean from
60S to 10N and 50E to 120E. It is driven at surface by
monthly SST and wind stress climatologies and run for one
year. Horizontal Circulation, Model climate drift for temperature
and salinity initial condition are described.
Data Assimilation Experiment in the East (Japan) Sea
Based on POM-ES
Young Jae Ro
Dept. of Oceanography, Chungnam National University
Yusung-ku, Kung-dong 220, Taejon, Korea, 305-764
The pattern of the East (Japan) Sea water circulation is still
poorly understood, owing to its highly complicated boundary
current system and their significant seasonal and interannual
variability. One of the most prominent features in the East
(Japan) Sea is the Polar Front separating the water masses
from the warm and saline water in the south supplied by the
Kuroshio and the cold and fresher water in the north. The formation
of the polar front in the East (Japan) Sea and its variability
is one of crucial processes in understanding the general
circulation in this region. This study will focus on this key
question with numerical modeling based on POM-ES. POMES
(Ro, 1999; 2000; 2001) was developed based on Princeton
Ocean Model with realistic bottom topography. Model configuration
is designed with grid resolution (1/10 deg), bottom
topography, boundary conditions (three open boundaries at
Korea, Tsushima, and Soya Strait with 3 (Sv) seasonally varying
transport), monthly surface forcings with wind stress and
radiation. POM-ES was initially spinned up with monthly
GDEM dataset in diagnostic mode for three years and ran for
next 30 years in prognostic mode with 3-D T-S nudging
scheme. Model is restarted with the final output with data assimilation
of satellite SST and T/P SSA Two schemes of data
assimilation (nudging and adjoint) are used.
Vertical Mixing Parameterizations and their effects on the
skill of Baroclinic Tidal Modeling
Robin Robertson
Lamont-Doherty Earth Observatory
The skill of different vertical mixing parameterizations was
evaluated with respect to baroclinic tidal modeling over Fieberling
Guyot using observational velocity and dissipation
data. The different parameterizations evaluated were generic
length scale, Pacanowski-Philandar (PP), a modification of PP
developed at Lamont-Doherty Earth Observatory (LDEO),
Large-McWilliams-Doney (LMD) Kp profile, a modification
of LMD developed by a group at Oregon State Univ., Mellor-
Yamada 2.5 level turbulence closure, and a Brunt-Väisälä frequency
based scheme. The generic length scale parameterization
was found to perform the best, followed by a modification
of the Pacanowski-Philandar parameterization made by a
group at LDEO Good agreement was found between the vertical
viscosity estimated by the model and observations in the
region.
Experimenting with Lagrangian Drifters in a
Washington Lake Using POM
Rubash, Lambert L.
Raincoast GeoResearch
Kilanowski, Elizabeth M.
Raincoast GeoResearch
To simulate drifter tracking experiments, POM was configured
for Lake Whatcom in northern Washington State and a
routine was written to advance an array of drifter positions
once for every cycle of the internal mode loop. A 300 x 100 x
21 cell grid was used and a masking technique was incorporated
to remove dry cells from computational loops.
Much of the lake's watershed is periodically logged, and a
significant and growing portion is residential; the lake itself
serves both recreational users, and as an industrial, and drinking
water source for the nearby city of Bellingham. Concern
about degrading water quality has created a need for publicly
available circulation data in an easily understood form.
Public discussion is generally based on an implied assumption
that the lake is a long, deep, narrow body of nearly still
water that slowly moves from southeast to northwest. Much of
the water that enters in the southeast is glacial meltwater that
is popularly thought to refresh and cleanse the lake, although a
settling pond is used to remove suspended solids before the
water enters the lake. Flushing time has been estimated to be
about 14 years, and this flushing time is often confused with
average water movement.
This study demonstrated that simulated drifter tracking can
provide circulation study data that contradicts public perceptions,
and yet is sufficiently accessible and intuitive to be able
to overcome public mistrust of scientific authority. The drifters
in this study also traced unsuspected local circulation patterns
that surprised researchers, but were as would be expected,
once revealed.
Modeling study of the coastal upwelling system of the
Monterey Bay area during 1999 and 2000.
Igor Shulman
Naval Research Laboratory, Stennis Space Center
Jeff Paduan, Leslie Rosenfeld, Steve Ramp
Naval Postgraduate School
John Kindle
Naval Research Laboratory, Stennis Space Center
The focus of this paper is to demonstrate the capability of a
Monterey Bay area high-resolution model (1-4 km and 30
vertical levels) to track the major features in an upwelling system
when constrained by the proposed measurement suite and
nested within a regional model. The model was originally configured
as part of the Innovative Coastal-Ocean Observing
Network (ICON) program. In order to include dominant flow
regimes from the California Current system and the important
effects of processes crossing from the deep water to the continental
shelf, the ICON model is nested within the regionalscale
NRL Pacific West Coast (PWC) model. The ICON
model has been forced with atmospheric products from both
coarser-resolution NOGAPS and finer-resolution COAMPS
Navy atmospheric models; the ICON model assimilates HF
radar-derived surface currents and MCSST data.
The ICON model simulations reproduce upwelling filaments
originating at Pt. Ano Nuevo and Pt. Sur north and
south of Monterey Bay, respectively. These upwelling filaments
form and decay with realistic space and time scales and
produce a realistic meandering front between the cooler, upwelled
water and the warmer water of the California Current.
A narrow, poleward-flowing California Undercurrent along
the continental slope is another realistic feature of the simulations.
Analyses of ICON model runs show that high-resolution
atmospheric forcing (e.g., COAMPS wind and heat fluxes) as
well as accurate open boundary conditions (e.g., PWC model
runs also forced with COAMPS) are equally critical for the
model accuracy within this relatively small (~100 km) domain.
Data assimilation of HF radar-derived surface current
maps is shown to improve model tracking of mesoscale features
between the surface and depths around 100 m.
Developing the Generalized Coordinate Ocean Model for
Multi-Scale Compressible or Incompressible Flow Applications
Tony Song
NASA/JPL
Two physical parameters are introduced into the basic ocean
equations to generalize an ocean model for using the optimal
or hybrid features of the commonly used z-level, terrainfollowing,
isopycnal, and pressure coordinates in a single numerical
configuration. The two parameters are formulated by
combining three techniques: the arbitrary vertical coordinate
system of Kasahara (1974), the Jacobian pressure gradient
formulation of Song (1998), and a newly developed parametric
function that permits both compressible (conserving mass)
and incompressible (conserving volume) flow conditions.
Based on the new formulation, a generalized modeling approach
is proposed and a staggered finite volume method is
designed to ensure conservation of important physical properties
and numerical accuracy.
Several representing oceanographic problems with different
scales and characteristics- coastal canyon, seamount topography,
and non-Boussinesq Pacific Ocean with nested
high-resolution cold-tongue region are used to test the proposed
new model. The results show that the model is capable
of resolving multi-scale processes with both compressible and
incompressible conditions in the same numerical configuration.
The inclusion of the compressible physics in the topography-
following ocean model does not incur computational expense,
but more faithfully represents satellite sensing data,
such as TOPEX sea-surface elevation and GRACE bottompressure
anomaly, which directly measure the changes of the
water mass, instead of the changes of the water volume. Such
a generalized coordinate model is expected to benefit diverse
ocean modelers for solving a variety of ocean-related problems
and for sharing modeling resources with less restrictions.
Application of a Three-Dimensional Numerical Model to
the Idealized Conditions of the Bosphorus strait
Adil Sozer and Emin Ozsoy
Metu Institute of Marine Sciences, Turkey
The Bosphorus strait is a narrow and shallow channel between
the Sea of Marmara and the Black Sea which plays an important
role in the Turkish Straits System connecting the Black
Sea and the Mediterranean Sea. Having the narrowest and
shallowest channel geometry within the System, it is the most
important element constraining the exchange between the
Black Sea the Mediterranean Seas.
In this study, the response of the strait is investigated with
respect to open boundary conditions corresponding to idealized
geometrical hydrographical conditions. The free-surface,
primitive equation ocean model, SCRUM, was used for numerical
simulations. Many simulations were performed including
the testing of boundary conditions, experiments with
different type of horizontal and vertical mixing and diffusion
parametrizations, advection schemes and tests of geometrical
effects as well as grid resolution and type.
These simulations showed the three-dimensional model to
be applicable to the special case of strait exchange flows. The
selection of the open boundary conditions is a non-trivial first
step for successful application of the model. The results obtained
from the tests with the idealized conditions corresponding
to Bosphorus Strait indicate the need for judicious choices
of boundary conditions, which depend on the flow direction.
However the results obtained with these choices and even the
case with purely radiation boundary conditions started from
the 'lock-exchange' initial condition support the existence of
maximal exchange controlled flows exemplified by observations
in the Bosphorus.
Surface currents and the Craig-Banner
boundary conditions
Charles Tang
Bedford Institute of Oceanography
The Princeton Ocean Model has been applied to the eastern
Canadian seas for studies of high-latitude processes and forecasting
of ocean conditions. Model results of circulation and
deep convection in Labrador Sea, seasonal variation of sea-ice
coverage, wind-driven surface currents will be shown. The
model gives satisfactory results except surface currents as can
be seen in a comparison of model simulated surface drifts and
trajectories of surface drifters deployed on the Grand Banks in
the fall of 2002. We propose that the lack of wave effects in
POM is mainly responsible for the discrepancy between model
and observation. The Craig-Banner boundary condition, the
Stokes drift and coupling of surface waves and Ekman layer
will be discussed.
Simulated Sea Surface Salinity Variability in the
Tropical Pacific
Xiaochun Wang, Yi Chao
JPL/Caltech
The Sea Surface Salinity (SSS) variability simulated by an
oceanic general circulation model forced by daily NCEPNCAR
reanalysis from 1990 to 2001 is analyzed in the letter.
With daily forcing, the model can reproduce SSS change of
the tropical Pacific on different timescales. The modelsimulated
SSS compares well with the Tropical Atmosphere
Ocean (TAO) mooring observation. The correlation coefficients
between the model output and observation are around
0.6 and significant at a level of 99% for selected sites that
have relatively long observations. The western tropical Pacific
is a large variability center on different timescales. On the
interannual timescale, the standard deviation of SSS in the
region could reach 0.4 practical salinity unit (psu). The 1997-
1998 ENSO event is associated with a freshening of the
whole equatorial Pacific with an amplitude as large as 0.6 psu.
However, the eastern equatorial Pacific shows relatively
weak SSS variability (0.1 psu), implying that the western
tropical Pacific and the eastern tropical Pacific have quite different
mechanisms of SSS changes. On the seasonal timescale,
the western tropical Pacific has variability around 0.3 psu. On
the intraseasonal timescale (timescale shorter than 50 days),
SSS variability in the equatorial Pacific has an amplitude of
0.1 psu. Relevance to the upcoming Aquarius satellite mission
to measure SSS from space is discussed.
Modeling the Summertime Heat Budget of Southeast New
England Shelf Waters
John Wilkin, Lyon Lanerolle
Institute of Marine and Coastal Sciences, Rutgers University
The Regional Ocean Modeling System (ROMSv2.0) has been
configured for a region of the southeastern New England shelf
encompassing the Coastal Boundary Layers and Air-Sea
Transfer (CBLAST) observation area. CBLAST observations
include precise measurements of air-sea fluxes of heat, momentum
and mass, and vertical profiles of turbulent mixing
throughout both the atmospheric and oceanic boundary layers.
Accordingly, these observations are ideally suited to critically
evaluating key components of a coupled ocean-atmosphere
modeling system.
An objective of the modeling study is to evaluate vertical
turbulence closure parameterizations in ROMS (KPP, Mellor-
Yamada, and the Generalized Length Scale scheme of Umlauf
and Burchard 2003) in a region of strong tidal forcing, strong
diurnal heating, yet low to moderate wind-speed conditions
(the CBLAST-LOW regime). Evaluating the respective merits
of the turbulence parameterizations is achieved by comparing
a geographically realistic model to observations in a setting
relevant to the development of a practical forecast system.
A further objective is to complement observational data
analysis. Horizontal stirring and advection are largely unobserved
by the CBLAST field instrumentation, yet these processes
affect the local heat budget at the Martha's Vineyard
Coastal Observatory (MVCO) meteorological tower site and
adjacent moorings. In particular, results to date show the local
heat balance at MVCO is significantly affected by the advection
of vertically mixed waters originating on the Nantucket
Shoals, tidally generated eddies transporting Vineyard Sound
water through Muskegat Channel, and cooling due to winddriven
upwelling to the southwest of Martha's Vineyard.
Port of New York and New Jersey Operational
Forecast System (NYOFS)
Eugene Wei
Coast Survey Development Laboratory, NOAA/NOS
Ted Caplow, Peter Schlosser
Department of Earth & Environmental Engineering
Columbia University
The real-time Port of New York and New Jersey Operational
Forecast System (NYOFS) became operational on February
10, 2003 at NOAA\'s National Ocean Service (NOS). NYOFS
includes a hydrodynamic model component and a suite of
software for processing input and output data, including
graphic applications.
The hydrodynamic model is based on the threedimensional
Princeton Ocean Model with a nested-grid configuration.
A high-resolution grid is embedded within and
dynamically connected to a coarse grid to provide detailed
current shears and eddies in the navigation channels of the Kill
Van Kull leading into the Port of Elizabeth and Newark Bay.
There is one-way coupling from the coarse to the fine grid and
the model is run in a three-dimensional barotropic mode.
NYOFS generates hourly nowcasts and hourly forecast guidance
out to 30 hours of currents and water levels. The system
has been incorporated into NOS\'s Physical Oceanographic
Real-Time System (PORTS(r)), which provides an operational
monitoring system (24 hours a day, 7 days a week) for quality
assurance and control of the NYOFS inputs, operational procedures,
and product dissemination.
In July, 2002, researchers from Columbia University's Department
of Earth & Environmental Engineering conducted a
deliberate SF6 experiment in Newark Bay to study the circulation
and dispersion in this estuary. By adding a routine for a
passive substance to NYOFS, the model appears capable of
reproducing the dominant mixing processes with appropriate
calibration. With calibrated configurations, the model is further
used to simulate tracer dispersion in assisting the planning
of a June, 2003 field experiment in the East River.