ECCO Achievements, Capabilities, Applications, and Future Plan

http://www.ecco-group.orgECCO funded in the past decade under NOPP with funding from NASA, NOAA, NSF, and ONR

Main focus: to provide physically consistent estimate of the state of the ocean to support climate research

Partners of various ECCO projects: JPL, MIT, AER, SIO, GFDL, NCEP, Harvard, NASA GSFC & ARC, U. of Hamburg, Argonne

Tony Lee, NASA JPL/Caltech

Final IGST Meeting, NOAA/CPO, Washington DC, June 2-4, 2008

ECCO Capabilities and Achievements

• Inverse estimation of the time-varying state of the global ocean (along with the estimation of initial & boundary conditions & parameters).

• Product serving: a suite of products (from multi-decadal to eddy-permitting) served through LAS, DODS, OPeNDAP.

• The physical consistency of ECCO products (e.g., consistent estimate of state and forcing and state, budget closure) is crucial to climate diagnostics.

• Budget components of T & S part of ECCO products.

• Adjoint tool for sensitivity analysis (process study & Obs. Sys. evaluation).

• Online tracer tools to study water-mass pathways (origin and destination) using forward & adjoint of passive-tracer equations based on ECCO-JPL product.

• Development of an open-source automatic differentiation tool.

• Assimilate a large suite of existing in-situ & satellite data using the adjoint method by adjusting prior surface forcing & initial conditions.

• MITOGCM, 1°x1°, 23 levels

• Delayed mode (1+ year lag)

• Current product period: 1992-2006

ECCO-GODAE MIT adjoint-based estimation

DATA CONSTRAINTS

Sea level: Altimetry (TOPEX/Poseidon, JASON-1, GFO, ERS-1/2, ENVISAT)

Sea level: tide gauges

Wind stress: scatterometry (NSCAT, ERS-1/2, QuikSCAT)

SST: AVHRR, TMI on TRMM; AMSR-E on Aqua

T & S climatology (time -mean & seasonal cycle)

T & S: CTD synoptic sections

T profiles: XBTs

T & S profiles: ARGO Floats

Sea surface salinity: in-situ survey

Temperature and velocity: TOGA-TAO mooring array

Sea ice concentration: SSM/I

Temperature & salinity: Elephant seal profiles (experimental)

Geoid: GRACE

G-ECCO: similar system, also a large ste. of data constraints, product 1950-2000

ECCO-GODAE JPL Kalman filter/smoother assimilation

• Assimilate altimeter-derived SSH & in-situ T profiles using Kalman filter/smoother method.

• MITOGCM & MOM4, 1°x0.3° in tropics, 1°x1° extra-tropics, 46 levels.

• Near real time (10-30 days lag).

• Product period: 1993 onward.

http://ecco.jpl.nasa.gov/

ECCO-2 High-res. Global-Ocean & Sea-Ice Data Synthesis

Velocity (m/s)At 15 m depth

• MITOGCM (Cubed-sphere)

• 18x18 km, 50 levels

• Product: 1992-2006

• Green’s function method

• Data constraint:

- SSH mean & anomaly

- T & S profiles (XBT, CTD, ARGO, TAO)

- SST (GHRSST)

- Sea ice concentration (SSMI)- Sea ice motion (radiometers,

QuikSCAT, RGPS)- Sea ice thickness (ULS)

http://ecco2.org

Control parameters:Initial T & S; atmospheric surface boundary conditions; background vertical diffusivity; critical Richardson numbers for KPP; air-ocean, ice-ocean, air-ice drag coefficients; ice/ocean/snow albedo coefficients; bottom drag and vertical viscosity

Comparison of mixed-layer temperature near cold tongue between ECCO-JPL product (curve) and TAO data (dots) (Kim et al. 2007)

Product Validation ExamplesDescribed in various publications for different subject of investigations

Comparison of mixed-layer temperature & velocity in tropical Indian Ocean between ECCO-JPL product & RAMA mooring data (Halkides & Lee 2008)

Evaluation of newly released ECCO-2 high-resolution Product using TAO mooring data at a “tough location”

ECCO-2 baseline

TAO

ECCO-2 release 1

0N, 165E 0N, 110W

Evaluation of newly released ECCO-2 high-resolution Product using TAO mooring data

Applications of ECCO products & tools for research

A wide-range of topics including (not limited to):

• Data assimilation & model improvement

• Ocean circulation

• Mixed-layer heat budget

• Sea level variability and changes

• Initialization of S-I prediction

• Biogeochemistry

• Geodesy

• Providing open-boundary conditions for regional systems.

Over 150 peer-reviewed publications in the past decade (not including many external-user publications)

The eastern box defined by Saji et al. (1999) spans areas with different forcing & ocean dynamics.

Differences in processes controlling MLT within the box need to be understood.

Variance of horizontal advective tendency suggest potential effects of equatorial currents in Box 1, coastal currents in Box 2, and South Equatorial Current in Box 3.

Mixed-layer temperature (MLT) balance in southeastern tropical Indian Ocean (SETIO) (Halkides & Lee 2008)

Application example

Box 1: equatorial

Box 2: coastal

Box 3: SEC

MLT budget in SETIO for 1994, 1997, & 2006 IODZM events: spatially inhomogenous & event dependent (Halkides & Lee 2008)

Horizontal advection warms in Box 1 but cools in Boxes 2 & 3 during IOZDM cooling

Subsurface processes cools in Boxes 1 & 2 but warms in Box 3 during IOZDM cooling

Horiz. Advection in Box 1 help terminate cooling in 94 & 06 but not 97

Application example

Made possible by budget closure

CO2

CO2 flux in tropical Pacific during ENSO inferred from a Kalman filter estimation (physically inconsistent) is unrealistically large (left), but that based on Kalman filter-smoother (physically consistent) is reasonable (right).

Kalman Filtered estimate Kalman-filter/smoother estimate

Importance of physical consistency to interdisciplinary applications (McKinley 2002)

Application example

• No significant slowdown of Atlantic MOC found.

• Serious issue of potential aliasing for analysis based on infrequent hydrographic sections because of large month-to-month & synoptic fluctuations.

Vertical distribution of volume transport (upper) & mid-depth transport time series (lower)

Variability of N. Atl. Meridional Overturning Circulation (Wunsch and Heimbach 2007)

Application example

Vertical partition in density trends due to–trends in temperature T–trends in salinity S–trends in T, S

TS S

T

Understanding decadal sea-level patterns (Wunsch et al. 2007)

Application example

Improvement of seasonal climate forecast by using

ECCO-JPL product as initial state in a coupled model (UCLA atmos. Coupled to

MITOGCM)

DJF hindcast for March initial conditions

Anomaly correlation increases with ECCO

Standard error reduces with ECCO

ECCO

baseline

persistence

ECCO

baseline

persistence

Cazes-Boezio, Menemenlis, and Mechoso, 2008: J. Climate, 21, 1929-1947 .

Application example

Future Plan of ECCO

Sustain production and accelerate improvement in support of climate research (e.g., CLIVAR sciences).

• Sustaining production of delayed-mode adjoint-based estimation system.

• Near real-time extension using Kalman filter/smoother.

• Enhancement of resolution.

• Improvement of error covariance.

• Expansion of control space (e.g., including mixing coeff.)

• Longer term: coupling with atmosphere & biogeochemistry.