1. Verfasser/in Webadresse, E-Mail oder sonstige Referenz GECCO ACTIVITIES (Armin Köhl, Nuno Sera, Nikolay Kuldenov) GECCO-2: Global (including Arctic), extension of GECCO, basically up-to- date GECCO configuration, with various mixing parameters as control; run over 10 - 20 years. GECCO-1 configuration, using new observations as constraints: GRACE, GOCE, SMOS. Atlantic/Arctic, 1/6 degree. Arctic reanalysis; nested in GECCO-2 New coupled adjoint (name of model still under construction): Hamburg Atmosphere (PLASIM) coupled to MIT Ocean; adjoint is being created form coupled model using TAF. Model is tested; to be released within next year.

2. Ute Webadresse, E-Mail oder sonstige Referenz model set-up: Tripolar grid, from 33°S to Bering Strait (i.e., including Mediter., Baltic, Nordic Seas and Arctic Ocean); 16 km and 50 levels; o.b.c. from global solution; NCEP atmospheric state+bulk formulae assimilation period: 2000-2010. assimilated observations: monthly temperature and salinity profiles from CTDs, XBTs and ARGO floats; daily along-track SSH anomalies from satellite altimetry; monthly SST from satellite microwave sensor. controls: initial temperature and salinity and surface boundary conditions: 2-m air temperature and humidity, precipitation, 10-m wind. model-observations misfit: reduced by about 40% (after 9 iterations). Largest individual cost reductions occurred for salinity (37%) and temperature (17%). Small improvement in SSH, since the forward integration SSH was already near accepted errors. It might also indicate that constraining eddy variability of an already eddying model is problematic. bias reduction for salinity and temperature (Fig. 1): - In the vertical, biases reduced mainly in the top 400m and in the layer 800-2000m. - The spatial distribution of the bias reduction shows a large impact at the exit of the Labrador Sea, also where the largest bias were found. mean corrections to NCEP atmospheric state (Fig. 2): - Air temperature corrections are dominated by cooling at localized places (e.g., Barents and Labrador Seas; north of the Gulf Stream). - Precipitation corrections show more precipitation over the Subpolar Gyre and less over the western boundary of the subtropical Atlantic (in particular over the Gulf Stream). - Wind corrections are important north of 40°N and show two strong cyclonic wind anomalies in the northern north Atlantic (south of the Grand Banks of Newfoundland and in the Icelandic Basin) and an anticyclonic wind anomaly over the Norwegian Sea. Atlantic-Arctic Oceans high-resolution ocean synthesis using the adjoint method (N. Serra, A. Köhl & D. Stammer) (a)(b) (c)(d) Fig. 1. Salinity (a) and potential temperature (b) biases from the unconstrained (black) and optimized (red) model integrations. (c,d) Salinity and potential temperature bias reduction (%) in the layer 1000-1500m. (a) (b)(c) (d) (e) Fig. 2. Mean corrections to the NCEP atmospheric state: (a) 2m air temperature (b) 2m air humidity, (c) precipitation rate and (d) 10m wind. Panel (e) shows a zoom of the wind (vectors) correction in the North Atlantic.