GSOP ReportGSOP Report

Detlef StammerDetlef Stammer

Universität HamburgUniversität Hamburg

CLIVAR/GODAE Synthesis Evaluation CLIVAR/GODAE Synthesis Evaluation EffortEffort

CLIVAR Reference Data Management CLIVAR Reference Data Management IssuesIssues

CLIVAR’s (WOAP’S) CLIVAR’s (WOAP’S) Synthesis NeedsSynthesis Needs

ChallengesChallenges

The spectrum of applications of ocean reanalyses for The spectrum of applications of ocean reanalyses for climate variability and prediction purposes spans over climate variability and prediction purposes spans over seasonal-to-interannual, decadal-to-centennial, and even seasonal-to-interannual, decadal-to-centennial, and even millennial time scales. millennial time scales.

These applications pose a range of accuracy and These applications pose a range of accuracy and robustness requirements on ocean reanalyses.robustness requirements on ocean reanalyses.

Consequently, they necessitate somewhat different data Consequently, they necessitate somewhat different data assimilation approaches and evaluation.assimilation approaches and evaluation.

Ocean SynthesisOcean Synthesis Several global ocean data assimilation products are Several global ocean data assimilation products are

available today that in principle can be used for climate available today that in principle can be used for climate applications. applications.

Underlying assimilation schemes range from simple and Underlying assimilation schemes range from simple and computationally efficient (e.g., optimal interpolation) to computationally efficient (e.g., optimal interpolation) to sophisticated and computationally intensive (e.g., adjoint sophisticated and computationally intensive (e.g., adjoint and Kalman filter-smoother). and Kalman filter-smoother).

Intrinsically those efforts can be summarized as having Intrinsically those efforts can be summarized as having three different goals, namely three different goals, namely – climate-quality hintcasts, climate-quality hintcasts, – high-resolution nowcasts, and high-resolution nowcasts, and – the best initialization of forecast models. the best initialization of forecast models.

Synthesis EvaluationSynthesis Evaluation Is needed to determine the quality of existing global ocean Is needed to determine the quality of existing global ocean

analysis/synthesis products and to assess their usefulness analysis/synthesis products and to assess their usefulness for climate research.for climate research.

Will focus on global results and their usefulness for climate Will focus on global results and their usefulness for climate research purposes, oriented along GSOP science research purposes, oriented along GSOP science questions. questions.

Needs to be done in a close collaboration with CLIVAR's Needs to be done in a close collaboration with CLIVAR's basin panels to serve their implementation, e.g., ongoing basin panels to serve their implementation, e.g., ongoing and planned regional process experiments.and planned regional process experiments.

QuantitiesQuantities

The intercomparison study is oriented along global The intercomparison study is oriented along global scientific questions: scientific questions:

1) THE OCEANS IN THE PLANETARY HEAT 1) THE OCEANS IN THE PLANETARY HEAT BALANCE: (1) heat storage, (2) heat transports BALANCE: (1) heat storage, (2) heat transports and (3) ocean/atmosphere feedbacks. and (3) ocean/atmosphere feedbacks.

2) THE GLOBAL HYDROLOGICAL CYCLE: 2) THE GLOBAL HYDROLOGICAL CYCLE: (1) water balance, (2) rainfall variability and (3) (1) water balance, (2) rainfall variability and (3) salinity and convection.salinity and convection.

3) SEA LEVEL: (1) sea level rise and (2) sea level 3) SEA LEVEL: (1) sea level rise and (2) sea level variabilityvariability..

GSOP/GODAE Synthesis Evaluation Workshop, GSOP/GODAE Synthesis Evaluation Workshop, Aug.31,Sept. 1, 2006 Aug.31,Sept. 1, 2006

at ECMWFat ECMWF..

The overall goals of the inter-comparison of global synthesis efforts The overall goals of the inter-comparison of global synthesis efforts are to:are to:

Evaluate the quality and skillEvaluate the quality and skill of available global synthesis of available global synthesis products and determine their usefulness for CLIVAR.products and determine their usefulness for CLIVAR.Identify the common strength and weaknessIdentify the common strength and weakness of these systems and of these systems and the differences among them, as well as to identify what application the differences among them, as well as to identify what application can be best served by what synthesis approach. can be best served by what synthesis approach. Define and test climate-relevant indicesDefine and test climate-relevant indices that in the future should that in the future should be provided routinely by ongoing or planned synthesis efforts in be provided routinely by ongoing or planned synthesis efforts in support CLIVAR and of the wider community. support CLIVAR and of the wider community.

Synthesis EvaluationSynthesis Evaluation

Individual synthesis efforts were ask to compute indices Individual synthesis efforts were ask to compute indices from their results prior to the workshop and make them from their results prior to the workshop and make them available to the project for further evaluation. available to the project for further evaluation.

Input has been solicited from individual basin panels Input has been solicited from individual basin panels regarding metrics and indices for global reanalyses and regarding metrics and indices for global reanalyses and the identification of CLIVAR reference data sets.the identification of CLIVAR reference data sets.

The evaluation effort will be based on results available The evaluation effort will be based on results available from the period 1950 to present, including those that cover from the period 1950 to present, including those that cover the TOPEX/JASON-1 era. the TOPEX/JASON-1 era.

MetricsMetrics

Systematic model-data comparison: Systematic model-data comparison: RMS RMS model data differences rel. to prior data errors.model data differences rel. to prior data errors.

Differences first guess/constrained model.Differences first guess/constrained model. Comparison to reference data sets, e.g., surface Comparison to reference data sets, e.g., surface

fluxes.fluxes. Comparison with time series stations.Comparison with time series stations. Computation of integral quantities.Computation of integral quantities. Budgets, e.g., heat content and its change.Budgets, e.g., heat content and its change. Model-Model differences (incl. first guess).Model-Model differences (incl. first guess).

Agenda (1)Agenda (1) THURSDAY, AUGUST, 31:THURSDAY, AUGUST, 31: 8:308:30 Goal of Synthesis Evaluation Effort and Charge to the meeting Goal of Synthesis Evaluation Effort and Charge to the meeting

(D. Stammer)(D. Stammer) 8:458:45 CLIVAR Data Sets (David Legler)CLIVAR Data Sets (David Legler) 9:159:15 CLIVAR Surface Flux Reference Data (Simon Josey)CLIVAR Surface Flux Reference Data (Simon Josey) 9:459:45 Discussion of Data and Error Requirements (Carl Wunsch)Discussion of Data and Error Requirements (Carl Wunsch) SUMMARY of individual Synthesis Projects (10 min. each + hand SUMMARY of individual Synthesis Projects (10 min. each + hand

outs)outs) 14:1014:10 Ocean Indices from Data (OOPC, Albert Fischer)Ocean Indices from Data (OOPC, Albert Fischer) 14:3014:30 CLIVAR/GODAE Metrics for Ocean Analysis (Detlef Stammer)CLIVAR/GODAE Metrics for Ocean Analysis (Detlef Stammer) 14:5014:50 Data archiving/DODS (Peter Hacker and Paco Doblas-Reyes) Data archiving/DODS (Peter Hacker and Paco Doblas-Reyes)

(10 min. each)(10 min. each) 15:3015:30 Group: RMS Model-Data misfits (P. Heimbach, D. Menemenlis)Group: RMS Model-Data misfits (P. Heimbach, D. Menemenlis) 16:3016:30 Group: Meridional Transports (A. Köhl)Group: Meridional Transports (A. Köhl) 17:3017:30 General DiscussionGeneral Discussion 18:0018:00 AdjournAdjourn

Agenda (2)Agenda (2)FRIDAY, SEPTEMBER, 1FRIDAY, SEPTEMBER, 1 8:308:30 Group: Surface Fluxes (L. Yu)Group: Surface Fluxes (L. Yu) 9:309:30 Group: Sea Level Changes (Magdalena Alonso-Group: Sea Level Changes (Magdalena Alonso-

Balmaseda)Balmaseda) 10:00 10:00 Group: Heat and Salt Content (Anthony Weaver)Group: Heat and Salt Content (Anthony Weaver) 11:0011:00 Group: Transports through key regions (T. Lee)Group: Transports through key regions (T. Lee) 13:0013:00 Group: Water Masses (K. Haines and T. Lee)Group: Water Masses (K. Haines and T. Lee) 14:0014:00 Group: Indices (A. Fischer)Group: Indices (A. Fischer) 15:3015:30 Carbon Program and Synthesis (D. Wallace)Carbon Program and Synthesis (D. Wallace) 15:50 15:50 General DiscussionGeneral Discussion 16:3016:30 Summary and Next StepsSummary and Next Steps 17:0017:00 END OF MEETINGEND OF MEETING

OutcomeOutcome

Quantitative statement of the skill of available global Quantitative statement of the skill of available global synthesis products and their usefulness for CLIVAR.synthesis products and their usefulness for CLIVAR.

Identification of common strength and weakness of Identification of common strength and weakness of systems and the differences among them.systems and the differences among them.

Definition of climate-indices and diagnostic quantities to be Definition of climate-indices and diagnostic quantities to be produced on a regular basis.produced on a regular basis.

Prototype synthesis support of global and regional CLIVAR Prototype synthesis support of global and regional CLIVAR research (will be extended as work progresses). research (will be extended as work progresses).

Basis for recommendations with regard to future synthesis Basis for recommendations with regard to future synthesis resource planning. resource planning.

GSOP Web site to present climate indices from ocean GSOP Web site to present climate indices from ocean syntheses over last 50 years.syntheses over last 50 years.

Counter part to OOPC indices from data alone.Counter part to OOPC indices from data alone. Stimulation for WGOMD and IPCC to join in. Stimulation for WGOMD and IPCC to join in.

Intercomparison Quantities:Intercomparison Quantities:

1. RMS Model-Data Misfits: (Discussion Leads: Patrick Heimbach and Dimitris 1. RMS Model-Data Misfits: (Discussion Leads: Patrick Heimbach and Dimitris Menemenlis)Menemenlis)

Difference from WOA01 climatological (monthly, Jan.-Dec.) potential T & SDifference from WOA01 climatological (monthly, Jan.-Dec.) potential T & S RMS misfit from Reynolds SSTRMS misfit from Reynolds SST RMS misfit from in-situ T & S profiles (including XBT, CTD, Argo, moorings)RMS misfit from in-situ T & S profiles (including XBT, CTD, Argo, moorings) RMS misfit from altimeter-derived SSHRMS misfit from altimeter-derived SSH RMS misfit from tide-gauge SSHRMS misfit from tide-gauge SSH2. Meridional Transports: (Discussion Lead: Armin Koehl)2. Meridional Transports: (Discussion Lead: Armin Koehl) Timeseries of the period 1950-present of meridional overturning transport Timeseries of the period 1950-present of meridional overturning transport

stream function of the global ocean, Atlantic (north of 34S), and Indo-Pacific stream function of the global ocean, Atlantic (north of 34S), and Indo-Pacific (north of 34S) as a function of latitude and depth and for the global ocean as a (north of 34S) as a function of latitude and depth and for the global ocean as a function of latitude and potential density. function of latitude and potential density.

Timeseries of the period 1950-present of meridional heat and freshwater Timeseries of the period 1950-present of meridional heat and freshwater transports of the global ocean, Atlantic (north of 34S), and Indo-Pacific (north of transports of the global ocean, Atlantic (north of 34S), and Indo-Pacific (north of 34S) as a function of latitude and Time series of maximum MOC strength and 34S) as a function of latitude and Time series of maximum MOC strength and heat transport at 25N, 48N in North Atlantic heat transport at 25N, 48N in North Atlantic

Intercomparison Quantities:Intercomparison Quantities:3. Heat and Salt Content (Discussion Leads: Magdalena Alonso 3. Heat and Salt Content (Discussion Leads: Magdalena Alonso

Balmaseda; Anthony Weaver)Balmaseda; Anthony Weaver) Monthly means of averaged temperature (proxy to heat content) and Monthly means of averaged temperature (proxy to heat content) and

salinty over the upper 300m/750m and 3000m.salinty over the upper 300m/750m and 3000m. Time series for spatial averages within a list of 30 pre-defined boxes in Time series for spatial averages within a list of 30 pre-defined boxes in

various parts of the ocean.various parts of the ocean.4. Sea Level Changes (Discussion Leads: Anthony Weaver and 4. Sea Level Changes (Discussion Leads: Anthony Weaver and

Magdalena Alonso Balmaseda)Magdalena Alonso Balmaseda) Monthly means of sea level, and optionally steric height and/or bottom Monthly means of sea level, and optionally steric height and/or bottom

pressure.pressure. Time series for spatial averages within a list of 30 pre-defined boxes in Time series for spatial averages within a list of 30 pre-defined boxes in

various parts of the ocean.various parts of the ocean.5. Transports through Key Regions: (Dsicussion Lead: Tong Lee)5. Transports through Key Regions: (Dsicussion Lead: Tong Lee) Indonesian throughflow volume transport Indonesian throughflow volume transport ACC volume transport through the Drake passage.ACC volume transport through the Drake passage. Florida Strait volume transport, temperature flux, and salinity flux.Florida Strait volume transport, temperature flux, and salinity flux.

Intercomparison Quantities:Intercomparison Quantities: 6. Water Masses: (Discussion Lead: Keith Haines and Tong Lee)6. Water Masses: (Discussion Lead: Keith Haines and Tong Lee) 18-C water volume in the N Atlantic Ocean, volumne-weighted average salinity of 18-C water volume in the N Atlantic Ocean, volumne-weighted average salinity of

the 18C water as a function of month.the 18C water as a function of month. Annual Maximum mixed layer depth within the Labrador sea and the T,S Annual Maximum mixed layer depth within the Labrador sea and the T,S

properties of that mixed layer. properties of that mixed layer. Warm-water volume in the equatorial Pacific (5S-5N, 120E-80W) AND tropical Warm-water volume in the equatorial Pacific (5S-5N, 120E-80W) AND tropical

Pacific (20S-20N, 120E-80W), Pacific (20S-20N, 120E-80W), Depth of 20 degree isotherm in Pacific Ocean as a function of longitude, latitude, Depth of 20 degree isotherm in Pacific Ocean as a function of longitude, latitude,

and month.and month.7. Indices: (Discussion Lead: Albert Fischer) 7. Indices: (Discussion Lead: Albert Fischer) Sea surface temperature anomaly indices averaged over lat-lon boxes in the Sea surface temperature anomaly indices averaged over lat-lon boxes in the

ocean. Here are the indices:ocean. Here are the indices:– Pacific: Nino1+2; Nino3; Nino3.4; Nino4 Pacific: Nino1+2; Nino3; Nino3.4; Nino4 – Indian: SETIO; WTIOIndian: SETIO; WTIO– N. Atlantic: Curry and McCartney transport index.N. Atlantic: Curry and McCartney transport index.

8. Surface Fluxes: (Discussion Lead: Lisan Yu)8. Surface Fluxes: (Discussion Lead: Lisan Yu) Monthly means of net surface heat and freshwater flux as function of geographic Monthly means of net surface heat and freshwater flux as function of geographic

location.location. Time mean of net surface heat flux and freshwater flux over entire model domain.Time mean of net surface heat flux and freshwater flux over entire model domain. Zonal averages of annual mean net surface heat flux and freshwater flux over the Zonal averages of annual mean net surface heat flux and freshwater flux over the

model domain.model domain.

Participating GroupsParticipating Groups ECCO (Estimation of the Circulation and Climate of the Ocean) (US)ECCO (Estimation of the Circulation and Climate of the Ocean) (US)

GECCO GECCO

SODA (Simple Ocean Data Assimilation) POP (US)SODA (Simple Ocean Data Assimilation) POP (US)

GFDL/NOAA (US)GFDL/NOAA (US)

NCEP/NOAA (US)NCEP/NOAA (US)

HYCOM (US)GMAO/GSFC (US)HYCOM (US)GMAO/GSFC (US)

ECMWFECMWF

INGV/ENACTINGV/ENACT

CERFACS-LODYC/ENACTCERFACS-LODYC/ENACT

UK Met Office?UK Met Office?

MERCATOR/MERSEA?MERCATOR/MERSEA?

MOVE-GMOVE-G

K-7K-7

BlueLinkBlueLink

WGOMD and/or IPCCWGOMD and/or IPCC

ENSEBLESMOCMOC

-15

-10

-15

-8

-11

-16

Min. Ind-Pac

MOC(Sv)

MOM 1-1/3o Lev KPP,GM

OPA,Lev, TKE

MOM3, 1o Lev, KPP,GM

OPA 2-1/2o,Lev, TKE, eddy vel

MOM

HOPE 1o,Lev

MIT CS,Lev,

MIT 1o,Lev

MIT 1o,Lev KPP,GM

MIT 1o, Lev, KPP,GM

MIT 1-1/3oLev KPP,GM

LSG 3.5oLev

Model Details

No

Yes

6Sv

(No)

7Sv

Yes

13Sv

(No) 4Sv

No

(No) 2Sv

No

……….

10.4-6.5

l-NADW

92 – 02

3-5km

(Yes) 1Sv no ov. 20S

(Yes) only S Atl.

Yes

6Sv

(Yes) not ov.Eq.

(Yes) not ov.Eq.

(Yes) 1Sv not ov.Eq.

Yes

………

1.2-2.5

AABW

North-Atl.

14(<27.72) …………..

………..

-4.016(<27.72) 19.4-14.8

SFL23G & W (2000) Bryden et al(2005)

22

25

30

17

18

19

19

Max. Atl. MOC (Sv)

adjointK-7

SOFA-OI

MERCATOR

DEPRESYS

adjointAWI

Method Details

Mean MOC 48N

(Sv)

Drift MOC 25N, 92-02 (Sv/10yrs)

Seasonal MOC 25N

(Sv)

STD MOC 25N (Sv)

Mean MOC 25N (Sv) MOC

adjoint170.21.7314ECCO-50yr

OI130.61.2417SODA

MOVE

multivar. OI

18-3.31.2322INGV

15-1.51.2314GFDL(TonyRosati)

OI-3.10.28216ECMWF (30N)

ECCO2-CS510

adjoint17-0.31.9314ECCO-GODAE

adjoint19-0.71.8316ECCO-SIO

partition Kalman

19-7.04.017ECCO-JPL

Bryden et al. (2006)

Strength of the MOCStrength of the MOC: shown ins the change in : shown ins the change in MOC strengths at 25 degree N from 50 yr MOC strengths at 25 degree N from 50 yr

optimization, from 11 yr optimization and from optimization, from 11 yr optimization and from Bryden et al., 2005Bryden et al., 2005

ECCO-SIO

ECCO-SIO/50y + Ref.ECCO-SIO/50y + Ref.

Bryden et al. (2005)

K-7

Max. MOC 25Max. MOC 25ooNN

Bryden et al. (2005)

ECMWF

ENSEBLES

Heat/FW transportHeat/FW transport

Heat/FW transport

Global Mean 25N (PW)

Global Mean 20S (PW)

Ind.-Pac. Mean 25N (PW)

Atl. Mean 25N (PW)

Atl. STD 25N (PW)

Atl. Seasonal 25N (PW)

Atl. Drift 25N (PW/10yr)

Global Mean FW 30S (Sv)

Global Mean FW 25N (Sv)

Model Details

Method Details

Ganachaud& Wunsch (2000)

1.80 -0.80 0.50 1.30Macdonald

(1998)0.72 -0.3

AWILSG 3.5o,Lev

adjoint

DEPRESYS

ECCO-JPL 1.45 -1.30 0.44 1.01 0.30 -0.37 0.50 -0.35MIT 1-1/3o, Lev KPP, GM

partition Kalman

ECCO-SIO 1.40 -0.44 0.45 0.96 0.21 0.13 -0.08 0.35 -0.31 MIT 1o, Lev, KPP, GM

adjoint

ECCO-50yr 1.26 -0.63 0.38 0.88 0.21 0.14 0.034 0.33 -0.31 MIT 1o,Lev, KPP, GM

adjoint

ECCO-GODAE

1.15 -0.78 0.33 0.82 0.21 0.13 0.033 0.55 -0.31 MIT 1o,Lev adjoint

ECCO2-CS510

MIT CS,Lev

ECMWF HOPE 1o,Lev

OI

GFDL 1.01 0.22 0.20 0.77 0.31 0.11 -0.018 MOM

INGV 2.2 -1.1 0.7 1.45 0.25 0.11 -0.27 0.82 -0.45 OPA 2-1/2o,Lev, TKE, eddy vel

multivar. OI

K-7 MOM3, 1o Lev, KPP,GM

adjoint

MOVE

MERCATOR

OPA,Lev, TKE

SOFA-OI

SODA 0.99 0.16 -0.08 MOM 1-1/3o Lev KPP,GM

OI

K-7

Global HeattransportGlobal Heattransport

Ganachaud&Wunsch(1996)

K-7

Heat transport 25Heat transport 25ooNN

Reference Data SetsReference Data Sets

In the context of CLIVAR's synthesis, CLIVAR reference In the context of CLIVAR's synthesis, CLIVAR reference data sets data sets and there error fieldsand there error fields are required for (1) the are required for (1) the analysis of climate processes; (2) for the evaluation of analysis of climate processes; (2) for the evaluation of assimilation and WGOMD simulations and (3) as data assimilation and WGOMD simulations and (3) as data constraints input to global synthesis. constraints input to global synthesis. CLIVAR reference data sets include in situ and satellite CLIVAR reference data sets include in situ and satellite data sets, as well as surface flux reference data sets, among data sets, as well as surface flux reference data sets, among others. others.

Köhl and Stammer (in preparation, 2006)

Input Data Sets and Controls

Reference Data SetsReference Data SetsExamples include:Examples include:SST Fields: Reynolds or Pathfinder SST, GHRSST-PP SST ReanalysisSST Fields: Reynolds or Pathfinder SST, GHRSST-PP SST ReanalysisSSH Fields: TOPEX/Poseidon and JASON-1 sea level anomaly from SSH Fields: TOPEX/Poseidon and JASON-1 sea level anomaly from AVISO or PO-DAACAVISO or PO-DAACTime-mean sea surface topography synthesized from drifter data and Time-mean sea surface topography synthesized from drifter data and T/P data (Niiler) and GRACE data. T/P data (Niiler) and GRACE data. De-tided tide-gauge data at selected stations with IB correction applied.De-tided tide-gauge data at selected stations with IB correction applied.Selected WOCE lines and corresponding times P01 (50º N), P03 (25º Selected WOCE lines and corresponding times P01 (50º N), P03 (25º N), P04 (10º N), P06 (30º S), P14 (dateline). A05 (25º N), A16N (20º W). N), P04 (10º N), P06 (30º S), P14 (dateline). A05 (25º N), A16N (20º W). I03 (20º S), I08N (80º E). TOGA-TAO, BATS, HOT, and Station P time I03 (20º S), I08N (80º E). TOGA-TAO, BATS, HOT, and Station P time series. series. Levitus climatological of temperature and salinity.Levitus climatological of temperature and salinity.Velocity Fields: Surface drifter (Niiler), 900-m float (Davis) velocities; Velocity Fields: Surface drifter (Niiler), 900-m float (Davis) velocities; ADCP data. ADCP data. Surface Flux fields: as defined by white paper of Josey and Smith Surface Flux fields: as defined by white paper of Josey and Smith (2006).(2006).

CLIVAR Reference Data SetsCLIVAR Reference Data Sets

Beyond CLIVAR's own needs, climate reference datasets Beyond CLIVAR's own needs, climate reference datasets are also required to meet wider needs for climate are also required to meet wider needs for climate information (GCOS Implementation Plan (IP), Key Action information (GCOS Implementation Plan (IP), Key Action 23). 23).

In particular the GCOS IP identifies the need for analysed In particular the GCOS IP identifies the need for analysed products for all Essential Climate Variables (ECVs) (will be products for all Essential Climate Variables (ECVs) (will be picked up at next GSOP-II meeting). picked up at next GSOP-II meeting).

Given CLIVAR’s responsibilities for the role of the oceans Given CLIVAR’s responsibilities for the role of the oceans in climate within WCRP, one of CLIVAR’s primary (but in climate within WCRP, one of CLIVAR’s primary (but indeed not sole) concerns lies in the area of reference indeed not sole) concerns lies in the area of reference datasets for the ocean ECVs and those related to air-sea datasets for the ocean ECVs and those related to air-sea exchange. exchange.

Thank You!Thank You!