S 1 CT1/CT3 Meeting April 2013 Hamburg WP 3.1 Suitability of the ocean observing system components for initialization Wonsun Park GEOMAR

Core Theme 3: Initialization of prediction systems with ocean observations (Lead: Steffen Olsen, DMI) WP 3.1 Suitability of the ocean observing system components for initialization (Lead: Mojib Latif, GEOMAR) Wonsun Park, Fritz Krueger, Thomas Martin

WP 3.1 Suitability of the ocean observing system components for initialization Objectives – To investigate the benefit of the different ocean observing system components for the initialization of decadal climate prediction systems – To quantify the impact of the different observing system components in terms of decadal hindcast skill – To identify the necessary enhancements and potential reductions of the present observing systems

22 ensemble runs with 1%/yr CO2 increase Natural variability is important at least till 40 yrs Latif and Park 2012

Observed multidecadal variability (ERSSTv3b) Pacific Decadal Variability vs. Atlantic Multidecadal Variability Park and Latif 2012

Centennial/multicentennial variability in observation and KCM Latif et al SSO index: SST averaged 50°-70°S

Internal modes Multicentennial/Quasicentennial/Multidecadal SST SSS Park and Latif 2012

Salinity restored to model climatology in the subpolar North Atlantic Ba et al. 2013

WP 3.1 Scientific work plan Perfect model approach Initialization: sampling according to existing ocean observing system components Hindcasts with reduced set of initial conditions Quantification contribution of different components of ocean observing system Investigate potential observational needs to enhance decadal prediction Comparison with other models (e.g. KCM with MPI- ESM)

Description of work Model setup and control run – Set up the coupled model and perform long control integration. – Choose a suitable set of initial states from the control integrations with regard to the Atlantic Meridional Overturning Circulation. Hindcast experiments and skill assessment – Do re-start experiments with truncated initial conditions that correspond to the different ocean observing system components, and with the full system. – Assess results in terms of hindcast skill. – Provide recommendations for a “suitable” observing system. Benefit of different Ocean regions – Do re-start experiments with truncated initial conditions which correspond to the different ocean regions, and with the global initialization, and assess the hindcast skill. [MPI-M]

The research leading to these results has received funding from the European Union 7th Framework Programme (FP ), under grant agreement n NACLIM