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ROMS/TOMS European WorkshopROMS/TOMS European WorkshopMaison Jean Kuntzmann, Grenoble, FranceMaison Jean Kuntzmann, Grenoble, France
October 7, 2008October 7, 2008
ean M od
earch C o m
r a i n - F o l l o w
M o d e l i n g
ROMS Framework and AlgorithmsROMS Framework and Algorithms
Hernan G. ArangoHernan G. ArangoInstitute of Marine and Coastal SciencesInstitute of Marine and Coastal Sciences
Rutgers University, New Brunswick, NJ, USARutgers University, New Brunswick, NJ, USA
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Outline
• Algorithms and Documentation Status
• The Good, The Bad, and The Ugly …
• Advection Operator
• Detiding Algorithm
• Observation Sensitivity
• Balance Operator
• Grid Nesting
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The Good… The Bad… The Ugly…
Adjoint Nesting Adjoint Maintenance
Data Assimilation Open Boundaries ROMS Code Divergence
ESMF/MCT Coupling Advection Operator Compiler Bugs
Released Version 3.1 Monotonicity Treatment of Rivers
WikiROMS Documentation Documentation
Forum Activity Wetting and Drying
ROMS Blog Parallel IO
www.myroms.org Grid Generation
Frequent Releases Tutorials
Version Control Post-processing
Copyright/Open Source
Algorithms and Documentation Status
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Advection Operator: North Atlantic (DAMEE_4)
Resolution 0.75x0.75 degrees
Grid 128x128x20
DX 40.8 - 95.8 km
DY 43.5 - 102.1 km
DT (5400, 200) sec
Bathymetry ETOPO-5
S-coordinates 5.0 and 0.4
Initial Conditions Levitus (1994), Feb
OBC Levitus (1994)
Forcing COADS, monthly
SSH, Year 10, Winter
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Hadv Vadv Hmix
T,S C2 C4 0
u,v U3 C4 0
Hadv Vadv Hmix
T,S C2 C4 50, H-G
u,v U3 C4 0
Hadv Vadv Hmix
T,S U3 C4 0
u,v U3 C4 0
Advection Operator: GOM ¾° resolutionInitial (red) and 10-year (blue) T-S Diagram Curves
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Hadv Vadv Hmix
T,S C4 C4 50, H-G
u,v U3 C4 0
Hadv Vadv Hmix
T,S C4 C4 2x1012,B-G
u,v C4 C4 8x1012,B-S
Hadv Vadv Hmix
T,S A4 A4 50, H-G
u,v U3 C4 0
Advection Operator: GOM ¾° resolutionInitial (red) and 10-year (blue) T-S Diagram Curves
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Hadv Vadv Hmix
T,S MPDATA MPDATA 0
u,v U3 C4 0
Hadv Vadv Hmix
T,S U3-S U3-S Yes, B-G
u,v U3-S U3-S Yes, B-S
Hadv Vadv Hmix
T,S U3-S U3-S Yes, B-G
u,v U3 C4 0
Advection Operator: GOM ¾° resolutionInitial (red) and 10-year (blue) T-S Diagram Curves
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Remarks
• There is excessive numerical, diapycnal mixing in the default
third-order, upstream-bias (U3) scheme.
• The second- and fourth-order centered differences schemes are
dispersive and overshoot.
• The MPDATA (Multidimensional Positive Definite Advection
Transport Algorithm) is monotonic and maintains the extrema.
However, there is some deep-water modification.
• The split schema (QUICK operator is split into advective and
diffusive components) is the best, showing few spurious maxima
and minima. However, the diffusion operator (along
geopotentials) has some stability problems that we need to
address.
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ROMS Tides Least-Squares FitA ROMS state variable, , can be represented in terms of its time mean, , plus a set of -tidal harmonics of frequency, .
The unknowns , , and coefficients are evaluated by minimizing the least-squares error function defined by:
Minimization subject to the additional constraints , , result in a linear set of equations:
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Least-Squares: Linear Equations System
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Tidal Forcing NetCDF File
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K1 (23.93 h) P1 (24.07 h) O1 (25.82 h) Q1 (26.87 h)
K2 (11.97 h) S2 (12.00 h) M2 (12.42 h) N2 (12.66 h)
Philippine Archipelago Tides: SSH Amplitude and Phase
B. Zhang
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Remarks
• The detiding algorithm (AVERAGES_DETIDE) is working nicely.
• As the number of tidal constituents increases, the time needed
to resolve the beat frequencies increases. That is, the beat
period (sum of all frequencies) becomes longer.
• For example, if only M2 and S2 components are used, the beat
period is around 28-days (spring-neap cycle). Therefore we need
to run for a least 28 days to resolve the harmonic coefficients in
matrix A.
• I recommend you have a single NetCDF for tidal forcing and
save a copy before using the detiding option since this algorithm
add new variables to it.
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PhilEx Real-Time Predictions
• ONR-DRI in the
Philippine Archipelago• Real-time forecasts to
support the PhilEx
Exploratory Cruise.• Coarse (~5 km) and
fine (~2 km) grid
resolution.• Initial and lateral
boundary conditions
from 1/12 HyCOM with
NCODA.• Forcing from NOGAPS
½, 3-hours forecast• Tides from global
OTPS model• Sequential 9-day
forecast cycles without
data assimilation
http://www.myroms.org/philex
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Philippine Archipelago
Forecast Salinity at 10m
J. Levin
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PhilEx 4DVar Assimilation: Salinity
J. Levin
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PhilEx 4DVar Assimilation: Temperature
J. Levin
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Intra-America Sea (IAS)• Real-time forecasts
onboard the RCCL vessel Explorer of the Seas.
• Running continuously since January 17, 2007 to present. Fully automatic since end of February 2007.
• IS4DVAR, 14-day sequential data assimilation cycles.
• 50 ensembles members per week running on a4-CPUs Linux box.
• Observations:
• Satellite SST
• Satellite SSH
• Shipborne ADCP
http://www.myroms.org/ias
Arango, Di Lorenzo, Milliff, Moore, Powell, Sheinbaum
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IAS 4DVar Observation Sensitivity: SSH
SSH observations SSH sensitivity
13-20 Apr 2007 13-20 Apr 2007
Arango, Moore, Powell
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IAS 4DVar Observation Sensitivity: SST
13-20 Apr 2007 13-20 Apr 2007
SSH observations SSH sensitivity
Arango, Moore, Powell
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Remarks
• We are still developing and fine tuning this algorithm
(OBS_SENSITIVITY).
• The mathematical formulation is similar to that of Zhu and
Gelaro (2008).
• It is a powerful tool to quantify the sensitivity of the IS4DVAR
system to the observations.
• It can help us to determine the type of measurements that need
to be made, where to observe, and when: Adapting Sampling.
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IS4DVAR Balanced Operator Covariances: EAC
The cross-covariances are computed from a single sea surface height observation using multivariate physical balance relationships.
Free-surface(m)2
Temperature(Celsius)2
Salinity(nondimensional)2
U-velocity(m/s)2
V-velocity(m/s)2
Z = -300m Z = -300m Z = -300m Z = -300m
Arango, Moore, Zavala
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IS4DVAR Balanced Operator Covariances: EAC
Free-surface(m)2
Temperature(Celsius)2
Salinity(nondimensional)2
U-velocity(m/s)2
V-velocity(m/s)2
The cross-covariances are computed from a single temperature observation at the surface using multivariate physical balance relationships.
Z = 0m Z = -300m Z = -300m Z = -300m
Arango, Moore, Zavala
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IS4DVAR Balanced Operator Covariances: EAC
Free-surface(m)2
Temperature(Celsius)2
Salinity(nondimensional)2
U-velocity(m/s)2
V-velocity(m/s)2
The cross-covariances are computed from a single U-velocity observation at the surface using multivariate physical balance relationships.
Z = -300m Z = -300m Z = 0m Z = -300m
Arango, Moore, Zavala
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Remarks
• We are still developing and fine tuning this algorithm
(BALANCE_OPERATOR).
• The approach is similar to that proposed by Weaver et al.
(2006).
• This is a multivariate approach to constraint the background and
model error covariances in the 4DVar system using linear
balance relationships (T-S empirical relationships, linear
equation of state, hydrostatic and geotrophic balances).
• It allows the unobserved variables information to be extracted
from directly observed quantities.
• State vector is split between balanced and unbalanced
components.
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Nested Grids Types
Refinement
Mosaics
Composite
Arango, Warner
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Grid
(ng)
Free-surface 2D Momentum 3D Momentum Tracers
West
East
No
rth S
ou
th W
est
East
No
rth S
ou
th W
est
East
No
rth S
ou
th W
est
East
No
rth S
ou
th
1
2
3
N: Nested C: Closed
F: Flather M: Clamped
G: Gradient P: Periodic
R: Radiation D: Reduced
H: Chapman
Nested Grids: Lateral Boundary Conditions
Arango, Warner
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Grid
(ng)P* West East North South
1 0 2 0 0 0
2 1 0 1 0 0
3 1 1 1 1 1
* Who is your parent? To whom are you connected to on ______ boundary edge?
1
32
Nested Grid Connectivity
Arango, Warner