Abstract. A unique set of coutemporaneous satellite-tracked drifters and five-day composite Advanced Very High Resolution Radionmeter (AVHRR) satellite imagery of the North Atlantic has been analyzed to examine the surface flow structure of the Gulf Stream. The study region was divided into two sections, greater than 37° N and less than 37° N, in order to answer the question of geographic variability. Fractal and spectral analyses methods were applied to the data. Fractal analysis of the Lagrangian trajectories showed a fractal dimension of 1.21 + 0.02 with a scaling range of 83 - 343 km. The fractal dimension of the temperature fronts of the composite imagery is similar for the two regions with D = 1.11 + 0.01 over a scaling range of 4 - 44 km. Spectral analysis also reports a fairly consistent value for the spectral slope and its scaling range. Therefore, we conclude there is no geographic variability in the data set. A suitable scaling range for this contemporaneous data set is 80 - 200 km which is consistent with the expected physical conditions in the region. Finally, we address the idea of using five-day composite imagery to infer the surface flow of the Gulf Stream. Close analyses of the composite thermal fronts and the Lagrangian drifter trajectories show that the former is not a good indicator of the latter.

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Undergraduate senior level physics majors taking Acoustics and oceanography majors taking Underwater Acoustics and Sonar learn about transmitting and receiving arrays (in one unit of their course) and do laboratory experiments to support and enhance the theoretical developments. However, there is a need to expose the students to a detailed unit on synthetic aperture sonar (SAS) while research at USNA is in progress and a teaching laboratory workstation is being developed. This paper communicates the teaching strategy on the topics describing: (a) how a strip-mapped SAS system works, (b) how matched-filtering relates to pulsed compression for a linearly modulated (LFM) pulsed chirp, (c) how synthetic aperture resolution is vastly improved over a conventional acoustic array, (d) how Fourier analysis is used in SAS, and (e) how a data set of N echoes can be used within a back-projection algorithm to obtain a two dimensional reflectivity image of an area (sea floor). Key points are (1) theory with visualizations to convey the teaching material to seniors in a two week period of time, (2) computer simulations, (3) classroom demonstrations in a water tank or in air, and (4) student involvement in a mini-research project using the computers and demonstration apparatus.

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