1.4
A near-real-time, high-resolution, ocean-surface-current mapping system
Jack A. Harlan, NOAA/ETL, Boulder, CO; and T. M. Georges, R. R. Leben, R. D. Palmer, J. Fernandez, and D. Flury
Two-dimensional synoptic-scale ocean surface current fields would be a useful component of an Integrated Ocean Observing and Prediction System. A NOAA-Navy partnership funded by NOPP has shown that a pair of over-the-horizon (OTH or skywave) radars can produce vector surface current maps in the deep ocean with spatial resolution of 10-15 km over areas greater than 105 km2 in near-real time. As an example, we show the complexity and time variability of the surface flow into the Gulf of Mexico through the Yucatan Channel. Mesoscale eddies are a recurring feature in the channel, and strong southward flow is present on its east side about half the time. These features are qualitatively confirmed by the tracks of surface-drifter buoys deployed during the Year of the Ocean. Comparisons of these radar-derived currents with satellite altimetry-derived geostrophic currents give a correlation coefficient of 0.78. Limited radar access led us to examine model-based spectral estimators to see if more ocean area could be scanned in the time allotted. Using simulations, we found the most significant advantage of the model-based methods was a reduction in the variability (standard deviation) of the resulting current estimates. In a parallel effort, we examined the use of high-resolution, adaptive beamforming methods with the intent of reducing the size of the needed antenna. These preliminary results suggest that smaller, less costly (by a factor of 1/4), antenna arrays could be built for a dedicated ocean observing radar system. One proposed two-radar configuration could cover the entire Gulf of Mexico and the hurricane approaches to the US East Coast.
Session 1, New Ocean Observing and Data Management Systems (NOPP Special Session)
Monday, 15 January 2001, 8:30 AM-12:30 PM
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