My main interest is understanding the general circulation of the ocean and its role in the global climate system. As part of the Estimating the Circulation and Climate of the Ocean (ECCO) consortium that originated under the National Oceanographic Partnership Program (NOPP), we are bringing together a state-of-the-art general circulation model (MITgcm) with most of the available satellite and in-situ observations to produce a best possible estimate of the time-evolving three-dimensional state of the global ocean and sea ice cover. To do so, we use formal estimation/inverse methods. It is now in its third phase, ECCO-IcES.