1 of 30 | © THOR (updated on ) THOR Core Themes Core Theme 1 MOC Variability Core Theme 3 Observations of the North Atlantic MOC 20-years Prediction Core Theme 2 Model Uncertainty Core Theme 5 Technological Advancements Core Theme 4 Predictability of MOC

2 of 30 | © THOR (updated on ) CT1: Understanding variability Analysis of Millennium-scale AOGCM experiments and paleo-records MOC and heat transport variations in the MPI-M model (Pohlmann et al., 2006) Dynamics of natural variability

3 of 30 | © THOR (updated on ) CT1 Sample Analysis: Completed and Ongoing Multicentennial scales MOC variability and its connection to the Southern ocean (Park, W., IfM-GEOMAR) Influence of the SAM (southern annual mode) on the AMOC variability (Marini, C., UPMC-LOCEAN) Design of sensitivity experiments to investigate influence of overflow and Labrador Sea Water variations onto the AMOC variability (Jungclaus J., MPG) The role of natural forcing for Atlantic multidecadal variability (Otterå, OH., UiB) Fresh water and heat content changes (Menary, M., MET O)

4 of 30 | © THOR (updated on ) CT1 | WP 1 Results: Response to External Solar Forcing Latif et al Met. Zeit. Jones and Mann (2004)

5 of 30 | © THOR (updated on ) Mean Sortable Silt at Gardar drift (Ninnemann et al. in prep) Reconstructed AMO based On three rings (Gray et al., 2004) CT1 | WP 2 Results: Mean Sortable Silt at Gardar Drift Gadar Drift data suggest that basin-wide warm phase is associated with vigorous ISOW flow - Explanation s. slide 6 -slide 6

6 of 30 | © THOR (updated on )  Multidecadal to centennial variability in ISOW vigor and chemical properties over the last ~600+ years  ISOW flow variability is coherent across a range of depths and space (not a local signal)  During the past ~350 years ISOW vigor is in phase with reconstructed AMO on both inter-decadal and centennial timescale—within the error of our age models.  This strong coherence suggests that low frequency variability in key components of AMOC is coupled to basin-wide temperature perturbations Summary of Observations CT1 | WP 2 Results: Mean Sortable Silt at Gardar Drift

7 of 30 | © THOR (updated on ) CT 1 Finding: Northern Hemisphere Temperatures & AMO Otterå et al., 2010, submitted to Nature Geoscience Generally compares well to reconstructed NH SAT and AMO  Model runs with natural forcing again reflects North Atlantic sea surface temperatures (AMV) from Palaeo observations  Volcanoes feature prominently in AMV

8 of 30 | © THOR (updated on ) The Early Warming Signal in the Arctic Courtesy of Lingling Suo, NERSC Early warming largely a forced signal in the model

9 of 30 | © THOR (updated on ) Ocean reanalyses and observations Sensitivity experiments CT2: Assessing uncertainties Assimilation of ocean data into models

10 of 30 | © THOR (updated on ) CT2 Achievements WP 2.1 Limitations of available observations and analysis systems in estimating the current state of the ocean  Exploiting a number of existing ocean analysis and hindcasts simulations: comparison of different independent state estimates  The ‘analysis’ are constrained by ocean observations but generally of coarse resolution  The ocean ‘simulations’ are run using surface fluxes only without assimilation of ocean observations  In addition, a set of focussed sensitivity experiments has been / will be performed with the DePreSys analysis system complementing the data impact studies  Time-series of state variables have been agreed upon. An initial evaluation against observations along the GSR mainly has been performed

11 of 30 | © THOR (updated on ) CT2 Achievements WP 2.2 The lack of modelling of the melt-water input from the Greenland ice sheet WP 2.3 Poor resolution of key small scale components of the THC and in particular their role in ocean freshwater redistribution modulating the THC  Coordinated experiments and analysis have been performed  Baseline experiments using HadCM3 and ECHAM5-MPIOM simulations with coupled atmosphere ocean ice-sheet climate projections  Running analysed for possible freshwater fluxes Furthermore, a number of simulations will be carried out in 2010 with 0.1 Sv freshwater perturbation along the coast of Greenland

12 of 30 | © THOR (updated on ) Model uncertainty Simple model inter-comparison document uncertainty on different scale and indicate a potential for identifying key processes of variability

13 of 30 | © THOR (updated on ) North Atlantic Subpolar salinity and its link to the fresh water exchange with the Arctic Ocean Some results on :  Hindcast simulation (ORCA05 model) forced by the ERA40 reanalysis  Sensitivity experiments to NAO-like atmospheric forcing WP 2.3: Result from UPMC-LOCEAN

14 of 30 | © THOR (updated on ) WP 2.3: Hindcast experiment | Salinity (200 – 500 m) EOF analysis GSA 2 distinct modes of upper salinity variability in the Subpolar North Atlantic  Labrador shelf mode  GSA mode

15 of 30 | © THOR (updated on ) Eastern gyre salinity WP 2.3: NAO-like experiments  salinity anomalies in the Eastern SPG Wind-only (NAO-like) Wind-only All fluxes m EOF 1 Wind-only All fluxes  Eastern gyre variability linked to NAO-like wind forcing  Little link to subpolar gyre index Gyre index Herbaut and Houssais, GRL, 2009

16 of 30 | © THOR (updated on ) Air-sea heat flux regressed on SSH in Smith Sound  SSH in Baffin Bay = lagged response to buoyancy forcing in the Labrador Sea WP 2.3: Hindcast experiment Mechanisms of SSH variability in Baffin Bay Upper salinity regressed on CAA fresh water outflow  Labrador Shelf mode linked to CAA outflow Sea Surface Height regressed on CAA fresh water outflow  Canadian Arctic Archipelago outflow partly controlled by SSH in Baffin Bay Houssais and Herbaut, subm. to JGR

17 of 30 | © THOR (updated on ) CT 3: Observing the circulation Labrador Sea shows overall warming since 1994 Overflow volume transport

18 of 30 | © THOR (updated on ) CT3: Observational Activities Nuno Nunes, updated on 02 April 2010

19 of 30 | © THOR (updated on ) CT3 Achievements WP 3.1 Sustained observations of ocean properties and fluxes through key sections  All THOR current meters moorings for the Atlantic inflow through the Denmark Strait (2 Aanderaa RCM instrumented moorings) and over the Iceland-Faroe Ridge (2 ADCPs in trawl-protected frames, and 2 deep traditional ADCP instrumented moorings) are in place  Most of the ADCP moorings for the Faroe-Shetland inflow are deployed  Two ADCP moorings to monitor the deep overflow were deployed in the Denmark Strait during the “Merian” cruises, and two ADCP moorings are deployed in the Faroe Bank Chanel

20 of 30 | © THOR (updated on ) CT3 Achievements WP 3.2 Monitoring watermass formation in convection regions south of the ridge  The Labrador Sea moorings at 53 N and 56 N were serviced in May/June 2009, during the RV Merian cruise MSM 12/1  Most instruments have complete data records for the respective deployment periods  The six moorings deployed will be serviced in July 2010 WP 3.3 Process studies  The entrainment study was carried out during the “Merian” cruise 2009

21 of 30 | © THOR (updated on ) The Faroe Bank Channel overflow Reproducing of a number of features of the observed transport time-series from seasonality to inter-annual variability: Identical seasonal amplitude and phasing High correlation (de-seasoned) Monthly r=0.7 (p<10 -7 ) Interannual r=0.9 (p<10 -4 ) Updated from Olsen et al. 2008

22 of 30 | © THOR (updated on ) PREDICATE: Sutton, 2004 CT 4: Predictability of the MOC Testing the quality of the forecasts. Forecasting until 2025

23 of 30 | © THOR (updated on ) CT4 Achievements WP 4.1 Coordinated Multi-model Ensemble Experiments to Assess the Predictability of the THC WP 4.2 Impact of Ocean Observations on THC predictions  Experimental multi-model set up for WP 4.1 clear (CMIP5/IPCC)  Perform runs and deliver results expected in July 2010, first multi-model THOR-AMOC review paper fall 2010  First test of protocol for observing system experiments done, experiments planned in 2011  Protocol for experiments separating initial state and radiative forcing, experiments planned in 2011

24 of 30 | © THOR (updated on ) WP 4.1: Skill of SST/T2m decadal predictions from coupled models 4 models: from ENSEMBLES project 3 ensemble members each Start dates november 1960, 1965,..., 2000 Reforecasts – no volcanic eruptions after analysis time Skill score: correlation coefficient Trend≡regression on CO2 concentration Van Oldenborgh et al, GRL, submitted

25 of 30 | © THOR (updated on ) WP 4.1: Skill in decadal predictions Atlantic Multidecadal Oscillation Clear skill in AMO yr 2-5 (r=0.7), some skill yr 6-9 (r=0.4)

26 of 30 | © THOR (updated on ) WP 4.2: Idealized experiments - AMOC Dunstone and Smith, 2010 InitialisationForecasts

27 of 30 | © THOR (updated on ) CT 5: Improving Methods The Bergen System ready to be deployed in Faroe-Bank-Channel ( ) Real data transmission from moorings

28 of 30 | © THOR (updated on ) Activities have been undertaken by the subcontractor FastOpt in Hamburg aiming at building of coupled assimilation capabilities, i.e. construct and demonstrate in pilot studies the use of a variational data assimilation system around a coupled model based on the Planet Simulator (Fraedrich et al., 2005), this containing  atmospheric component: PUMA (successfully applied in a feasibility study on parameter estimation, Kaminski et al., 2007)‏  Terrestrial vegetation component: SIMBA  Thermodynamic sea-ice component  Slab ocean to be replaced by MIT's oceanic general circulation model (MITgcm, Marshall et al., 1997) CT 5: Improving Methods Assimilation into coupled models

29 of 30 | © THOR (updated on ) 16-Months THOR: – Overall Activities and Achievements Kick-off meeting held in Hamburg Distribution of Grant to 20 partner institutes THOR website Cruise Maria S. Merian (Uni Hamburg) CT3 workshop First ADCPs purchased and deployed CT4 workshop Cruise Pelagia (NIOZ, NL) CT1 workshop Cruise Scotia (SAMS & Marine Scotland) CT2 workshop 1st Annual Meeting at UPMC Paris 1st Deliverables (D5-D9) delivered and issued to EC Data Management CT1 & CT3 run First reference data set (CT3) available* Modeling data (CT1) available for analysis * Reference data collection incl. hydrographical, float and mooring data for the Labrador and Irminger Seas + from the RAPID array

30 of 30 | © THOR (updated on ) Overview of Deliverables* No.Deliverable nameWP no. Deliverable due Status D1Working data and WEB server available for partners, consortium agreement signed.6.1Dec.2008  D2Data standards and policy defined **6.1Mar.2009 D3Design and implementation of public THOR WEB site6.1May 2009  D4Up to date estimates of ocean state2.1ongoing  D5Initial evaluation of ocean reanalyses and simulations of THC-related variables, from approximately 1960-present, against independent observations. 2.1Nov.2009  D6Reference data set for pre-existing data on properties and fluxes through key sections: Greenland-Scotland Ridge, Deep Western Boundary Current and across 26.5° N 3.1Nov  D7Reference data set for pre-existing data on properties, water mass renewal in the Labrador and Irminger Seas 3.2Nov  D8Summary data set for historical overflow entrainment studies (also s. Milestone 4)3.3Nov  D9Report on test data set experiments from coupled model.5.2Nov  * Deliverables 5-9 are available to download on the THOR website (publications) ** Observation (CT3) and model (CT1) data are available online (through THOR website, CT3 data login THORdc)