![Page 1: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/1.jpg)
After WOCE
what are the remaining challengesand how should we set about meeting them?
Jürgen Willebrand, IfM Kiel
Input appreciated from:G. Holloway, P. Killworth, W. Large
J. Marotzke, T. McDougall, J. SarmientoR. Schmitt, P. Rhines, C. Wunsch
Thanks to A.Biastoch
![Page 2: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/2.jpg)
WOCE and beyond, San Antonio 2002
WOCE Goals
Goal 1:
to develop models for predicting climate change,collect data necessary to test models
Goal 2:
to determine representativeness of WOCE data sets for long-term behavior of the ocean, and to find methods to determine long-term changes
![Page 3: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/3.jpg)
WOCE and beyond, San Antonio 2002
WOCE Achievements (short version)
to 1:
- models greatly improved (but far from perfect) - WOCE data give unprecedented view of global ocean but important gaps in understanding remain- test of models against data usually qualitative
to 2:
- large variability on interannual/decadal time scales found- much progress with technologies to determine long-term changes
![Page 4: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/4.jpg)
WOCE and beyond, San Antonio 2002
What else has changed since 1980 ?
Better understanding of
• role of ocean circulation for climate
• record of past changes
• role of circulation for biogeochemistry / ecology
• role of other parts of earth system for global change
• global change has arrived
![Page 5: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/5.jpg)
WOCE and beyond, San Antonio 2002
View of SurfaceTemperature Changes 1000 – 2100
Past and projected surface temperature anomalies - Mann et al reconstruction- Instrumental record- IPCC scenarios
J. Gould
![Page 6: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/6.jpg)
WOCE and beyond, San Antonio 2002
Goals for post - WOCE research
Goal 1:
to develop ocean models for simulating past and future changes in ocean circulation, climate and environment,collect data as necessary to test models
Goal 2:
to continuously and adequately observe the ocean on a global basis
![Page 7: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/7.jpg)
WOCE and beyond, San Antonio 2002
Goal 1 specific objectives
1. to understand ocean processes/mechanisms relevant for ocean circulation variability at all time scales (PO-community)
2. describe and understand large-scale ocean variability at all time scales, and its role for climate (PO with climate and paleo communities)
3. understand interaction of ocean circulation with environmental changes (PO with biogeochemical / ecological communities)
![Page 8: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/8.jpg)
WOCE and beyond, San Antonio 2002
1. Understanding processes / mechanisms
a) Mixingb) Effects of mesoscale eddiesc) Interaction with topography
d) improve air-sea fluxese) is ocean in equilibrium with 20th century forcing?f) relation convection - sinkingg) interaction w. sea-ice
. . .
z) Energy balance of circulation
To be addressed by process experiments, theory, modeling ...
Where applicable, ‚understanding‘ should eventually translate into physically-based parameterizations for models!
![Page 9: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/9.jpg)
WOCE and beyond, San Antonio 2002
processes / mechanisms cont’d
a) Mixing
- How is the mixing distributed in the ocean? How can we find out? Consequences of spatial variations?
- Dynamics and energetics (local/global) of mixing?
- Under which conditions diffusivities for T/S are different?
- On what time scales mixing becomes important for circulation changes?
- Which mixing processes support the THC? Where do they occur?
![Page 10: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/10.jpg)
WOCE and beyond, San Antonio 2002
processes / mechanisms cont’d
b) Effects of mesoscale eddies
- eddy tracer transports (bolus transport, pv vs. layer thickness diffusion ...) local vs. non-local effects
- momentum exchange with mean circulation
- connection of lateral stirring with diapycnal mixing?
- percentage of eddy energy used for diapycnal mixing
- parameterizations of sub-mesoscale processes
![Page 11: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/11.jpg)
WOCE and beyond, San Antonio 2002
processes / mechanisms cont’d
c) Interaction of circulation with topography - parameterizations of unresolved topography
- barotropic recirculations
- flow through straits
- slope convection
- ...
Denmark Strait pot.density (R. Käse)
![Page 12: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/12.jpg)
WOCE and beyond, San Antonio 2002
Overflow representation effects large-scale overturning
Kleine BildunterschriftText
J. Dengg
![Page 13: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/13.jpg)
WOCE and beyond, San Antonio 2002
2. Describe/understand large-scale variability and ocean’s role in climate
CLIVAR organization along time scales:Seasonal - Interannual:
El Nino, Monsoon systems ...emphasis on predictability / prediction
Decadal - centennial: - Subpolar/subtropical circ: response to atm. forcing patterns (e.g. NAO) - Cross-equatorial transports/cells, coupling w/ extratropics - thermohaline circulation...Data from combination of observations, analysis of historical data sets, reconstructions from proxy- data (e.g. corals, tree rings, ..)
Anthropogenic climate change: prediction + detection
![Page 14: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/14.jpg)
WOCE and beyond, San Antonio 2002
North Atlantic overturning in climate change simulations (IPCC 2001)
THC evolution in greenhouse scenario: large model dependence
Good argument for
- modelers to improve their models
- observers to start measuring THC change
![Page 15: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/15.jpg)
WOCE and beyond, San Antonio 2002
THC evolution in greenhouse scenario: large model dependence
Latif et al. (2000)
Latif (2002, pers. comm.)
Ocean modelresponsible for difference?
![Page 16: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/16.jpg)
WOCE and beyond, San Antonio 2002
Labrador Sea convection may stop even in stable THC scenario
U.Schweckendiek (2002, pers. comm.)
![Page 17: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/17.jpg)
WOCE and beyond, San Antonio 2002
Role of ocean for climate variability
Tropical oceans:- dominant influence on seasonal/interannual var. (e.g. El Nino)- strong influence also on decadal extratropical var. (e.g. NAO)?
Mid-latitude oceans:- very little influence on interannual-decadal var. (except through heat storage)- some influence on interdecadal var. ?
Recently:- role of ocean heat transport challenged by atmospheric modelers
but:- thermohaline circ. dominant for centennial/millenial var. ?
![Page 18: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/18.jpg)
WOCE and beyond, San Antonio 2002
Centennial-millenial climate variability during last glacial
Temperature from sediments and ice cores (Rahmstorf, 2002)
Millenial time scales (not part of CLIVAR)allow view of different dynamical regimesopens possibility to obtain long-term perspective
so far most explanations involve thermohaline circulation changes„Physics of most paleo-models is unimpressing“
![Page 19: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/19.jpg)
WOCE and beyond, San Antonio 2002
3. Interaction ocean circulation – environment
Understand role of ocean circulation for
- transport of radiatively active gases (CO2, methane) - natural carbon cycle and anthrop. perturbation- ocean ecosystem/biological pump
- natural variability and response to greenhouse warming
joint observations where possibleforward/inverse modeling of joint system
Help interpreting paleo-record by modelingpaleo-proxies (e.g. 13C, 18O), sedimentation rates..
![Page 20: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/20.jpg)
WOCE and beyond, San Antonio 2002
OCMIP-2: Anthropogenic CO2 Flux, Storage and Transport
Large model dependence
![Page 21: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/21.jpg)
WOCE and beyond, San Antonio 2002
Resolution Dependence of Anthropogenic CO2 Flux
(poster Biastoch et al.)
4/3° resolution 1/3° resolution
December 1989, in mol/m∆/yr
![Page 22: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/22.jpg)
WOCE and beyond, San Antonio 2002
Simulated Surface Chlorophyll in an Eddy-resolving model
A.Oschlies
![Page 23: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/23.jpg)
WOCE and beyond, San Antonio 2002
Can we learn from biol. distributions about ocean physics?
A.Oschlies
SeaWiFS surface chlorphyll 10S-12S during 1998 Rossby wave propagation(Kawamiya and Oschlies, 2002)
![Page 24: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/24.jpg)
WOCE and beyond, San Antonio 2002
Ocean model development
- parameterization of subgrid-scale processes- models should be sufficiently adiabatic
- what resolution is sufficient for a) convergence of coupled climate integrations? b) convergence of eddy energy / WBC structure? c) convergence of biological production? d) convergence of eddy stirring effects? e) numerical convergence?
- model errors should be quantified- model hierarchies helpful- same circulation models for physical oceanography, biogeochemical and paleo applications
- software engineering
![Page 25: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/25.jpg)
WOCE and beyond, San Antonio 2002
Observing System(s)
- design: follows from objectives and techn./econ. possibilities climate prediction climate change detection ocean prediction (e.g. ecosystem) understanding ocean variability applications ..
- should evolve with technological advances
- should stay close to assimilation activities
![Page 26: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/26.jpg)
WOCE and beyond, San Antonio 2002
Combining observations and models (assimilation)
- obtain global state estimation on ongoing basis
- develop robust methods that work a) with non-Gaussian statistics b) with chaotic models
- include biogeochemical state variables
Proof of the (assimilation) pudding is in the eating!
![Page 27: After WOCE what are the remaining challenges and how should we set about meeting them?](https://reader030.vdocuments.mx/reader030/viewer/2022032709/5681306f550346895d965095/html5/thumbnails/27.jpg)
The End