We thank all members of the ECCO Consortium for their direct or indirect support and discussions that lead to the results that are presented in this paper. In particular, Elisabeth Remy, Christian Eckert, and Patrick Heimbach were instrumental for setting up the ECCO 1° assimilation infrastructure. Youyu Lu, Charmaine King, Diana Spiegel, and Kyozo Ueyoshi helped with the processing of the input data. We also thank Lee Fu and two anonymous reviewers who suggested many improvements to the manuscript. Don Chambers from the University of Texas provided the T/P-GRACE dynamic topography (based on the GRACE model GGM01S). Reanalysis surface forcing fields from NCEP–NCAR were obtained through a computational grant at NCAR. SSH drifts were estimated from the Ssalto/Duacs maps, produced as part of the Environment and Climate EU Enact project (EVK2-CT2001-00117) and distributed by Aviso, with support from CNES. Computational support from the National Partnership for Computational Infrastructure (NPACI) and NCAR is acknowledged. Support was provided in part through ONR (NOPP) ECCO Grants N00014-99-1-1049, NAG5-11765, NAG5-12870, and NNG04GF30G, and through a contract with the Jet Propulsion Laboratory (1205624). This is a contribution of the Consortium for Estimating the Circulation and Climate of the Ocean (ECCO) funded by the National Oceanographic Partnership Program.
This paper is a tribute to Carl Wunsch and his long-held vision of the way the ocean state and its changes should be diagnosed through a modern observing system and through a quantitative model–data combination. One of his outstanding contributions to physical oceanography is his pioneering development of inverse methods in oceanography that today enables the community to perform routine ocean-state estimation. This is equivalent to weather prediction for the atmosphere and is intended to support operational oceanography as well as climate research. Carl had not only this vision but also the energy to move the field forward from “business as usual” into a new way of thinking about the ocean and how it should be observed and modeled—a vision that finally led to the establishment of a consortium among MIT, the Jet Propulsion Laboratory, and the Scripps Institution of Oceanography: Estimating the Circulation and Climate of the Ocean. It has also led to the ongoing international Global Ocean Data Assimilation Experiment (GODAE).
Thinking about Carl’s work, many other pioneering contributions to physical oceanography and to our understanding of how the ocean works come to mind. His role in the conception of the World Ocean Circulation Experiment (WOCE) is well known. An important observational component of WOCE was the U.S.–French satellite altimeter mission, called TOPEX/Poseidon. Perhaps some do not know that this satellite mission goes back to the vision of a few, including Carl, who understood the importance of having continuous coverage of satellite altimeter observations of the ocean: a satellite is the only tool that can observe ocean variability on all relevant time and space scales. History now has proven the concept to be correct by making the TOPEX/Poseidon mission the longest and most successful NASA mission to date and establishing altimetry as an important component of ongoing and future climate observing systems.
Beyond his own important scientific contributions and his leadership, Carl’s impact can also be measured by the number of students and young scientists he has advised since 1966 or had influenced significantly during their careers. From our experience we can say that Carl has the unique ability to stimulate and entrain young scientists into cutting-edge research discussions, which in many ways is as important as his outstanding expertise in the field. For many peers, Carl’s stimulating enthusiasm about their work has helped to make significant progress and evolution in the field. It is this sparkle, as much as his scientific accomplishments, that demonstrates Carl’s truly remarkable leadership.
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