The goal of Argo is to observe large-scale variability in the heat and hydrological cycles, including patterns in heat content, salinity anomaly, and transport by ocean circulation. Upper ocean temperature and salinity variability mirrors the effects of anomalous air-sea exchanges of heat and freshwater. Deeper in the water column, anomalous temperature and salinity are the result of subduction and advection of interannual and decadal climate signals. In addition to tracking variability, Southern Hemisphere Argo floats will explore remote regions of the globe where little is known of mean properties and ocean circulation. A number of examples of tropical and southern results from the early Argo dataset are described in this presentation, including surface layer variability, mode water formation, and thermocline and mid-depth T/S changes and circulations. Argo has many applications, including operational uses as well as research. Argo data are contributing substantially to the subsurface dataset used for data assimilation and model initialization.
The Southern Hemisphere oceans provide a strong challenge for Argo. In the completed Argo array, two-thirds of floats must be deployed south of the equator because of the hemispheric asymmetry in ocean area. Nearly all of the float-providing nations are in the north. Hence, both regional priorities and problems of access to remote ocean locations must be overcome for the program to succeed. There has never been a sustained ocean-scale array of subsurface measurements in the Southern Hemisphere, but the scientific payoff will be great. Southern Hemisphere deployments have begun and there are regional arrays of floats in each of the ocean basins. Large numbers of floats will be deployed in southern waters beginning in 2003.
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