Towards a High-Resolution Global-Ocean and Sea-Ice Data Synthesis

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Towards a High-Resolution Global-Ocean and
Sea-Ice Data Synthesis Seminar presented at UC,
Irvine on May 2, 2007 Dimitris Menemenlis Jet
Propulsion Laboratory Outline Background and
Motivation ECCO2 project description Some early
science results http//ecco2.org/
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Summary of 22-23 January 2007 ECCO2
meeting Overview and Motivation
ECCO, ECCO-GODAE, ECCO2 (Wunsch, MIT) The only
way to understand the complete, global,
time-evolving ocean circulation is to use all
available data and all available theory. ECCOn
seeks the best possible estimate of the
time-evolving ocean circulation, its influence on
climate, chemistry, biology, etc., understanding
of predictability, and determination of what we
do not understand. A two generation
problem! ECCO2 and NASA satellite missions (Fu,
JPL) Observations of mesoscale and sub-mesoscale
ocean variability are a key requirement for
understanding regional and global climate
processes. For this reason, wide swath altimetry
has been endorsed by the NRC Decadal Survey as a
possible new NASA mission. ECCO2 provides a
framework for utilizing high-resolution data from
existing and future NASA satellite missions.
Estimated sea level trend, spatial mean removed
(Wunsch, Ponte, and Heimbach, 2007).
Ground tracks of TOPEX/Jason tandem mission
superimposed on satellite imagery of sea surface
temperature.
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ECCO2 High-Resolution Global-Ocean and Sea-Ice
Data Synthesis
MIT Marshall, Heimbach, Hill Wunsch JPL Fu, Kwok,
Lee Menemenlis Zlotnicki GSFC Rienecker
Suarez ARC Henze, Taft HARVARD Tziperman GFDL Adcr
oft ARGONNE Hovland, Utke
Velocity (m/s) At 15 m depth
Objective synthesis of global-ocean and sea-ice
data that covers the full ocean depth and that
permits eddies. Motivation improved estimates
and models of ocean carbon cycle, understand
recent evolution of polar oceans, monitor
time-evolving term balances within and between
different components of Earth system, etc.
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Summary of 22-23 January 2007 ECCO2
meeting Assimilation and Modeling
Towards an ECCO2 release (Menemenlis/Zhang,
JPL) A first least squares minimization of the
global-ocean and sea-ice cube sphere (CS510)
model resulted in a 64 decrease of cost function
wrt temperature and salinity climatologies. These
state estimates are already being used in a host
of science applications Eddy permitting state
estimation (Mazloff/Heimbach, MIT) Adjoint method
state estimation in the presence of vigorous
mesoscale eddy variability has been shown to be
possible in a regional, high-resolution, Southern
Ocean model configuration. ECCO2 high
resolution modeling (Hill/Menemenlis/Henze) High-r
esolution global-ocean and sea-ice simulations
are being used to estimate error statistics, to
experiment with multiscale assimilation, to
improve parameterizations of unresolved
processes, and to drive the development of
petabit/petaflop infrastructure.
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Using model Greens functions to fit an
eddy-permitting global-ocean and sea-ice model to
satellite and in-situ data
Drake Passage Transport
Baseline
170Sv
140Sv
2002
2005
1992
Optimized
This first optimization improves Southern Ocean
circulation and stratification (M. Schodlok)
RGPS RGPS
Baseline Optimized November
1997 April 1998 April 1998
April 1998
A Greens function approach is being used to fit
a high-resolution configuration of the MITgcm to
satellite and in-situ ocean and sea ice data.
Top panel shows temperature difference in top 700
m between WGHC climatology and a 1992-2002
baseline integration driven by NCEP.  Bottom
panel shows temperature difference from WGHC for
an integration whose initial conditions, surface
boundary conditions, and internal model
parameters have been calibrated using 30 forward
sensitivity integrations (H. Zhang).
Optimized minus Baseline time-mean wind
difference
but it degrades Arctic Ocean sea ice
distribution and freshwater budget (R. Kwok and
A. Nguyen).
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http//ecco2.jpl.nasa.gov/products/output/cube/
Towards obtaining the first optimized solution,
some fifty forward sensitivity integrations have
been computed and are available for analysis.
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Southern Ocean State Estimate Mazloff and
Heimbach, MIT Currently optimizing year
2005. First guess initial conditions and open
boundary conditions derived from
coarse-resolution ECCO solution. First guess
atmospheric state from NCEP reanalysis. Data
constraints mean and time-variable sea surface
height, sea-ice concentration, in-situ
temperature and salinity profiles, sea surface
temperature, and hydrographic climatology.
25ºS to 78ºS 1/6º horizontal grid spacing 42
depth levels with partial cells i.e., 1/3 grid
points of global config. KPP and GM-Redi Bulk
formulae and sea-ice model
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Cost associated with misfit to sea surface
height anomaly Iteration 4 Mean 1.1
Cost change Iteration 4 - Iteration 0
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Investigating global ocean model solution
convergence
1/16
1/4
1/8
1/4
1/8
1/16
Hill, Menemenlis, Ciotti, and Henze.
Investigating solution convergence in a global
ocean model using a 2048-processor cluster of
distributed shared memory machines. J.
Scientific Programming, 2007.
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Depth of ocean surface turbulent mixing layer
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Summary of 22-23 January 2007 ECCO2 meeting Early
User Applications
Subtropical mode water (Maze, MIT) Eddy
propagation velocity (Fu, JPL) GRACE data
constraints (Zlotnicki, JPL) Errors estimates
(Forget, MIT) Eddy parameterizations (Ferreira,
MIT) Arctic freshwater budget (Condron,
WHOI) Arctic sea ice budget (Kwok, JPL) Sea ice
data/model comparison (Nguyen, JPL) Carbon cycle
modeling (Manizza, MIT) Eddy variability in
Indian Ocean (Lee, JPL) Darwin project (Hill,
MIT) Southern Ocean (Schodlok, JPL) MITgcm
assimilation efforts (Cornuelle, SIO) Adjoint
assimilation efforts (Edwards, UCSC )
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Mode water formation
(Marshall, Maze, and Hill, MIT) Objective is to
study the dynamics of eighteen-degree mode water
formation in the North Atlantic through
analytical, numerical and observational
approaches.
Marshall (2005). CLIMODE a mode water dynamics
experiment in support of CLIVAR. Clivar
Variations, vol.3, pp. 8-14.
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Observing and Modeling Ocean Eddies Containing
90 of the kinetic energy in the ocean, ocean
eddies (storm of currents) with scales from
10-100 km, are difficult to observe and simulate.
Using data from TOPEX/Poseidon, Jason, and ERS
radar altimeters, the energy level and
propagation velocity of eddies were estimated and
compared to a high-resolution simulation from the
MIT-JPL ECCO Model. Shown below is an example in
the Argentine Basin.
Eddy sea surface variability and propagation
velocity from altimetry
ECCO2 simulation
Coastal tides not included in the model
cm
cm
10 km/day
L-L. Fu D. Menemenlis
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Estimating global hydrographic variability
(Forget and Wunsch, MIT) Objective is to estimate
the three-dimensional global oceanic temperature
and salinity variability, omitting the seasonal
cycle, both as a major descriptive element of the
ocean circulation and for use in the error
estimates of state estimation.
Variance of T at 200m (left) and 400m (right) in
(oC)2 as estimated from the data (upper) and as
simulated by an ECCO2 simulation (lower).
Forget and Wunsch. Estimated global hydrographic
variability. J. Phys. Oceanogr., 2007.
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David Ferreira
Total meridional heat transport
GW
Most of the meridional eddy heat flux is achieved
in the top 200m of the ocean!
Total eddy heat transport
by diabatic eddies!
Eddy heat transport in top 200m
Not yet adequately parameterized in large-scale
coarse-resolution models
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3400 km3/yr (0.1 Sv) freshwater added from 54
arctic rivers for 11 years into cube 47. Approx.
60 of discharge is from May-July
Lena
Mackenzie
Ob and Yenisey
2002
1992
Surface salinity anomalies (cube 47-cube 43)
(negative fresher)
River discharge penetrating into interior.
A. Condron and P. Winsor, WHOI
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Interpretation of ICESat altimetric and
reflectivity profiles Kwok (JPL), et
al. Objective is to provide an assessment of the
ICESat altimeter for studying the Arctic Ocean
and to examine the magnitude of the large- and
small-scale expressions of geophysical processes
embedded in the elevation profiles.
Kwok, Cunningham, Zwally, Yi (2006). ICESat over
Arctic sea ice Interpretation of altimetric and
reflectivity profiles. J. Geophys. Res., vol.
111, doi10,1029/2005JC003175.
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Synthesis of the Arctic System Carbon Cycle
McGuire (Fairbanks), Follows, Manizza (MIT), et
al.
Objective is to study Arctic region carbon cycle,
including (a) exchanges between marine and
terrestrial carbon pools and (b) possible
exchanges between these large carbon reservoirs
and the atmosphere. ECCO2 solutions will be used
to drive offline carbon/biogeochemistry models
leading to improved estimates and models of
air-sea-land-ice exchanges of CO2 in the presence
of realistic eddying flows and with active
biological and chemical processes.
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Darwin project (Follows and Hill, MIT)
Prochlorococcus analogs
Synechococcus small eukaryotes
Diatoms
Other large eukaryotes
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Summary ECCO2 project aims to produce
increasingly accurate syntheses of all available
global-scale ocean and sea-ice data at
resolutions that start to resolve ocean eddies
and other narrow current systems.A first public
ECCO2 ocean state estimate, obtained using model
Greens functions, is scheduled for this
summer. Adjoint state estimation in the presence
of vigorous eddying circulation has been
successfully demonstrated. A number of early
user projects have started using pre-release
ECCO2 solutions.
http//ecco2.jpl.nasa.gov/products/