The ECCO High-Resolution Global-Ocean State Estimation Initiative ARC: Bob Ciotti, Chris Henze, and Jim Taft JPL: Benny Cheng, Ichiro Fukumori, Tong Lee, and Dimitris Menemenlis MIT: Alistair Adcroft, Patrick Heimbach, Chris Hill SIO: Armin Koehl and Detlef Stammer UW: Jinlun Zhang During the past four years, the consortium for Estimating the Circulation and Climate of the Ocean (ECCO) has demonstrated the feasibility and utility of providing global, sustained, dynamically reasonable estimates of the full three-dimensional, time-varying oceanic state. Remotely-sensed (altimeter, scatterometer, ocean temperature, and gravity) and in-situ (temperature and salinity profilers, mooring, drifter, and float) data and advanced estimation methods (adjoint model, Kalman filter, and Rauch-Tung-Striebel smoother) are used to constrain a state-of-the-art numerical ocean model and to produce best estimates of the large-scale oceanic circulation. These estimates are made available in near-real-time and are being used for a wide variety of scientific and operational applications. The ECCO experience has shown that it is possible to carry out these computations and that the resulting estimates possess significant value. Unfortunately, the computational demands for such a system are enormous, limiting the existing ECCO products to rather coarse resolutions (30 to 100-km horizontal grids). With this limited resolution it is not possible to adequately represent the many small-scale features of the oceanic circulation (western boundary currents, eddies, convection, etc.) that are important both for climate studies and for operational applications. To address this deficiency and to more fully utilize the available satellite and in-situ data, NASA is committing significant new computational resources to the ECCO project. This presentation will review existing ECCO products and applications and summarize the motivation, objectives, and status of the ECCO high-resolution ocean state estimation initiative. http://www.ecco-group.org