Adjoint Model Applications
The ability to efficiently linearize CFD (computational fluid
dynamics) codes is a crucial element in the analysis of the
predictability of fluid flow. Predictability is limited by three
fundamentally different factors; understanding of each being greatly enhanced by the use of linearized fluid codes:
| Initial Conditions:
Skillful
prediction of flow evolution is possible only when the
initial conditions are determined with sufficient accuracy.
An improved estimate of the state of the fluid can be
obtained by combining observations from a certain time
period with a model, which performs interpolation and
extrapolation in space and time. Very large-scale problems
can be solved through a minimization approach using the
adjoint to the CFD code. MITgcm is
being used by us to synthesize
observations in a dynamical framework to create
new ocean atlas products
read
more... |
| The physical model: The physical model must represent all important
processes influencing flow evolution, either by resolving
them explicitly or parametrically. Both testing a fluid code
against observations and determining parameters in
parameterizations of unresolved flow scales lead to
very large optimization problems. Such problems can be solved very
efficiently using the adjoint to the CFD code. |
| Hydrodynamic Instabilities:
Hydrodynamic instabilities lead to rapid growth of small
perturbations and, via the same mechanism, of error growth.
It is crucial to identify the fastest growing flow
perturbations and how they are triggered. The tangent-linear
model and its adjoint permit the computation of the singular
vectors of the the linearized operator describing flow
evolution, which often describe the most rapid growth of
perturbations and forecast error. The availability of the
linearized operator also facilitates the construction of
bifurcation diagrams by continuation methods - a powerful
tool in the analysis of the onset of hydrodynamic
instability or the establishment of flow regimes in the
vicinity of unstable critical points. |
As the adjoint capability of MITgcm has expanded, so
CMI researchers have been exploring adjoint applications in
various areas. Click on the icons below to explore a selection
of recent adjoint
applications...
Publications:
Heimbach, P., C. Wunsch, R.M. Ponte, G. Forget, C. Hill, and
J. Utke, 2010: Timescales and Regions of the Sensitivity of
Atlantic Meridional Volume and Heat Transport Magnitudes: Toward
Observing System Design. submitted to Deep Sea Res.
(special issue on the AMOC)
Zanna L., P. Heimbach, A.M. Moore and E. Tziperman, 2010.
Optimal excitation of interannual Atlantic meridional
overturning circulation variability. J. Climate,
Mazloff, M.R., P. Heimbach and C. Wunsch,
2010: An Eddy-Permitting Southern Ocean
State Estimate. J. Phys. Oceanogr.,
in press, doi:10.1175/2009JPO4236.1.
Zanna L., P. Heimbach, A.M. Moore and E. Tziperman,
2010. Optimal growth of Atlantic SST anomalies in an
idealized ocean GCM. J. Phys. Oceanogr., in
press, doi:10.1175/2009JPO4196.1.
2009
Baehr, J., S. Cunningham, H. Haak, P. Heimbach, T.
Kanzow and J. Marotzke, 2009: Observed and simulated
daily variability of the meridional overturning
circulation at 26.5°N in the Atlantic. Ocean Sci.,
5,
575-589.
Heimbach, P. and V. Bugnion,
2009: Greenland ice sheet volume sensitivity to
basal, surface, and initial conditions, derived from
an adjoint model. Annals of Glaciology,
50(52),
67-80.
Hoteit, I., B. Cornuelle, and P. Heimbach, 2009: An
Eddy-Permitting, Dynamically Consistent Adjoint-Based
Assimilation System for the Tropical Pacific:
Hindcast Experiments in 2000.
J. Geophys. Res., in press, doi:10.1029/2009JC005437
Sannino, G., M. Herrmann, A. Carillo, V.
Rupolo, V. Ruggiero, V. Artale and P.
Heimbach, 2009: An eddy-permitting model of
the Mediterranean Sea with a two-way grid
refinement at Gibraltar. Ocean Modelling,
30(1), 56-72, doi:
10.1016/j.ocemod.2009.06.002
Wunsch, C. and P. Heimbach, 2009: The
globally integrated ocean circulation (MOC),
1992-2006: seasonal and decadal
variability. J. Phys. Oceanogr.,39(2),
351-368, doi:
10.1175/2008JPO4012.1
2008
Wunsch, C., P. Heimbach, R. Ponte, I.
Fukumori and the ECCO-GODAE Consortium
members, 2008: The global general
circulation of the ocean estimated by the
ECCO Consortium. Oceanography,
22(2),
88-103.
Menemenlis, D., J.M. Campin, P. Heimbach,
C. Hill, T. Lee, A. Nguyen, M. Schodlock and
H. Zhang, 2008: ECCO2: High resolution
global ocean and sea ice data synthesis. Mercator
Ocean Quarterly Newsletter, 31, October
2008.
Vinogradov, S.V., R.M. Ponte, P.
Heimbach and C. Wunsch, 2008: The mean
seasonal cycle in sea level estimated from a
data-constrained general circulation model. J.
Geophys. Res., 113,
C03032, doi:10.1029/2007JC004496
Wunsch, C. and P. Heimbach, 2008: How
Long to Oceanic Tracer and Proxy
Equilibrium? Quaternary Science Reviews,
27, 637-651, doi:10.1016/j.quascirev.2008.01.006.
Wunsch, C. and P. Heimbach, 2008: Reply
to Saunders et al.’s Comments on “Decadal
changes in the North Atlantic meridional
overturning circulation and heat flux”.
J. Phys. Oceanogr., 38(9), pp.
2108-2110, doi:10.1175/2008JPO3936.1
2007
Heimbach, P. and C. Wunsch, 2007:
Estimating the Circulation and Climate of
the Ocean – The ECCO Consortia. U.S.
CLIVAR Variations, 5(3), December
2007, pp. 1-5.
Ponte, R.M., K.J. Quinn, C. Wunsch, and
P. Heimbach, 2007: A comparison of model and
GRACE estimates of the large-scale seasonal
cycle in ocean bottom pressure. Geophys.
Res. Lett., 34,
L09603, doi:10.1029/2007GL029599
Wunsch, C. and P. Heimbach, 2007:
Practical global ocean state estimation. Physica
D, 230(1-2), pp.
197-208, doi:10.1016/j.physd.2006.09.040
Wunsch, C., R. M. Ponte, and P. Heimbach,
2007: Decadal trends in sea level patterns:
1993-2004. J. Clim., 20(24),
5889-5911, doi:10.1175/2007JCLI1840.1
2006
Dutkiewicz, S., M.J.
Follows, P. Heimbach and
J. Marshall, 2006:
Controls on ocean
productivity and air-sea
carbon flux: An adjoint
model sensitivity
study. Geophys. Res.
Lett., 33,
L02603, doi:10.1029/2005GL024987
Heimbach, P., R.M.
Ponte, C. Evangelinos,
G. Forget, M. Mazloff,
D. Menemenlis, S.
Vinogradov and C. Wunsch,
2006: Combining
Altimetric and All Other
Data with a General
Circulation Model.in:
Proceedings of the 15
Years of Progress in
Radar Altimetry
Symposium, Venice,
13-18 March 2006, ESA
Special Publication
SP-614, ISBN
92-9092-925-1. ESA
Publications Division,
ESTEC, 2200 AG Noordwijk,
The Netherlands.
Wunsch, C. and P. Heimbach, 2006:
Estimated Decadal
Changes in the North
Atlantic Meridional Overturning
and Heat Flux 1993-2004.
J. Phys. Oceanogr.,
36(11),
2012–2024, doi:10.1175/JPO2957.1.
2005
Ferreira, D., J.
Marshall and P. Heimbach,
2005: Estimating eddy
stresses by fitting
dynamics to observations
using a residual-mean
ocean circulation model
and its adjoint. J.
Phys. Oceanogr.,
35(10),
pp. 1891-1910, doi:10.1175/JPO2785.1.
2004
Hill, C., V.
Bugnion, M. Follows and J. Marshall (2004) Evaluating carbon
sequestration efficiency in an ocean circulation model by
adjoint sensitivity analysis. JGR Oceans, vol 109, C11005,
doi:10.1029/2002JC001598
2003
Stammer, D.,
C. Wunsch, R. Giering,
C. Eckert, P. Heimbach,
J. Marotzke, A. Adcroft,
C. Hill, J. and J.
Marshall, 2003:
Volume, heat and
freshwater transports of
the global ocean
circulation 1992-1997,
estimated from a general
circulation model
constrained by WOCE
data.J. Geophys. Res., 108
(C1), 3007, doi:10.1029/2001JC001115.
2002
Stammer, D.,
C. Wunsch, R. Giering,
C. Eckert, P. Heimbach,
J. Marotzke, A. Adcroft,
C. Hill, J. and J.
Marshall, 2002:
The global ocean
circulation during
1992-1997, estimated
from ocean observations
and a general
circulation model. J.
Geophys. Res., 107
(C9), 3118,doi:10.1029/2001JC000888.
Stammer et al (2002) Global Ocean Circulation during 1992-1997,
estimated from ocean observations and a general circulation
model. JGR, Vol 107, No C9, 3118
