The ECCO2

1
The ECCO2 High Resolution Global-Ocean and
Sea-Ice Data Synthesis D. Menemenlis (JPL) H.
Zhang (JPL) C. Hill (MIT) 2008 Ocean Sciences
Meeting Orlando, Florida Date 03-05-2008 Time
1515 Session 036 1. Motivation 2.
Methodology 3. Assessment 4. Applications
2
Objective global, full-depth, time-evolving, and
physically-consistent synthesis of ocean and sea
ice data at a resolution that permits
eddies. Motivation - fuller utilization of
satellite and in-situ data, - improved ocean and
sea ice models, - understand recent evolution of
polar oceans, - study the oceanic carbon cycle, -
monitor time-evolving term balances within and
between the different components of the Earth
system, - etc.
3
(No Transcript)
4
Greens Function Estimation Approach (Stammer and
Wunsch 1996 Menemenlis and Wunsch 1997
Menemenlis, Fukumori, and Lee 2005)
GCM
x(ti1) M(x(ti),?)
Data yo
H(x) ? G(?) ?
Cost function J
?TQ-1? ?TR-1?
Linearization G(?)
G(0) G? G is an np matrix, where n is the
number of observations in vector yo and p is the
number of parameters in vector ?. Each column of
matrix G can be determined by perturbing one
element of ?, that is, by carrying out one GCM
sensitivity experiment.
GCM-data residual yd yo
G(0) G? ? Solution
?a
PGTR-1yd Uncertainty covariance P
( Q-1 GTR-1G )1 The solution satisfies the
GCMs prognostic equations exactly and hence it
can be used for budget computations, tracer
problems, etc.
5

• Data constraints
• sea level anomaly from altimeter data
• time-mean sea level from Maximenko and Niiler
  (2005)
• - sea surface temperature from GHRSST-PP
• temperature and salinity profiles from WOCE,
  TAO, ARGO, XBT, etc.
• sea ice concentration from passive microwave
  data
• sea ice motion from radiometers, QuikSCAT, and
  RGPS
• - sea ice thickness from ULS
• Control parameters
• initial temperature and salinity conditions
• - atmospheric surface boundary conditions
• background vertical diffusivity
• - critical Richardson numbers for Large et al.
  (1994) KPP scheme
• - air-ocean, ice-ocean, air-ice drag coefficients
• ice/ocean/snow albedo coefficients
• - bottom drag and vertical viscosity

6
Assessment of ECCO2 vs CLIVAR/GODAE
metrics Session 036 poster
0-750-m Temperature
0-750-m Salinity
WOA05
Baseline WOA05
Optimized WOA05
7
Assessment of ECCO2 in the Arctic Ocean Session
036 poster
Baseline data
Optimized data
Sea ice velocity comparison with SSM/I data
Fram Strait sea ice area export
Baseline Optimized Data
8
Assessment of ECCO2 in the Southern
Ocean Session 036 poster
Drake passage transport
Baseline GRACE Optimized Sloyan Rintoul, 2001
9

• Summary and Concluding Remarks
• A high-resolution, time-evolving, estimate of
  global ocean circulation and sea ice has been
  obtained using a Greens function approach.
• Relative to baseline integration, this estimate
  is significantly closer to hydrographic and sea
  ice data and to independent transport estimates.
• Ongoing ECCO2 work is focusing on
• improved representation of high-latitude
  sub-grid scale processes
• (overflows, salt plumes, sea-ice dynamics,
  restratification,
• ice-shelf-ocean interactions, etc.)
• regional studies and application of the adjoint
  method (Southern Ocean,
• Arctic Ocean, Weddell Sea, Beaufort Sea, North
  Atlantic, etc.)
• science applications (eddy-mean flow
  interactions, Arctic freshwater
• and sea-ice budgets, water mass formation
  processes, carbon cycle
• modeling, etc.)

10
ECCO2 Presentations at OSM08
Arctic freshwater budget Session 034 poster
CLIVAR/GODAE metrics Session 036 poster
Sea state bias Session 006 poster
Arctic Ocean and sea ice Session 036 poster
Jessica Hausman
Southern Ocean and land/sea ice Session 036
poster
Arctic carbon cycle Session 014 presentation
Comparison with GRACE data Session 145 poster
Zapiola anticyclone Session 036 poster
Adjoint model applications Session 012
presentation
http//ecco2.org/