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CSIRO Marine and Atmospheric Research
Past Seminars

Seminar Abstract

Design requirements for an Argo float array in the Indian Ocean inferred from observing system simulation experiments

Despite the relatively low cost of the Argo-based observing system component, the costs of construction and deployment still pose limitations on the total number of floats that will be deployed in the foreseeable future. To maximize the use of data provided by the limited number of floats available, it is necessary to design optimal sampling strategies. Experiments using output from an Ocean General Circulation Model have been performed to assess sampling strategies for the Argo array in the Indian Ocean. The results suggest that spatial sampling is critical for resolving intraseasonal oscillations in the upper ocean, i.e. about 500km in the zonal and about 100km in the equatorial meridional direction.

Frequent temporal sampling becomes particularly important in dynamically active areas such as the western boundary current regime and the equatorial waveguide. High frequency sampling is required in these areas to maintain an acceptable signal-to-noise ratio, suggesting a minimum sampling interval of 5 days for capturing intraseasonal oscillations in the upper Indian Ocean. Sampling of seasonal-and-longer-term variability down to 2000m depth is less critical within the range of sampling options of Argo floats, as signal-to-noise ratios for sampling intervals up to about 20 days are almost always larger than one. However, these results are based on a single OGCM and are subject to model characteristics and errors.

Based on a coordinated international effort, results from various models could provide more robust estimates by minimizing the impact of individual model errors on sampling strategies. Ongoing and planned international and national activities in the area of integrated observing system design will be described.

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CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
Peter Oke, (Oceanographic seminars) CSIRO Marine Research (03) 6232 5387
Keith Hayes, (Biological seminars) CSIRO Marine Research (03) 6232 5298
Katrina Nitschke, Antarctic Climate and Ecosystems CRC (03) 6226 2265 & IASOS, University of Tasmania (03) 6226 2509