Acoustic tomography in the Straits of Florida

Chester, David B.

doi:10.1575/1912/5394

Cited by 3 publications

(1 citation statement)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Over the last decade the instrumentation has advanced to a state which is more adequate to address the original intent. Several experiments have demonstrated the success of acoustic tomography in monitoring the oceanic temperature field, current velocities, and vorticity field (e.g., Howe et al, 1987;;Ko et al, 1989;Chester et al, 1991;Howe et al, 1991;Spiesberger and Metzger, 1991;Worcester et al, 1991;). Recent tomographic programs illustrate the evolution and versatility of the tomographic measurement.…”

Section: Introductionmentioning

confidence: 99%

A tomographic view of the Gulf Stream southern recirculation gyre at 38 degrees N, 55 degrees W

Chester¹

1993

Self Cite

View full text Add to dashboard Cite

Reciprocal acoustic transmissions made in a region just south of the Gulf Stream are analyzed to determine the structure and variability of temperature, current velocity, and vorticity fields at the northern extent of the southern recirculation gyre. For ten months (November, 1988 through August, 1989), a pentagonal array of tomographic transceivers was situated in a region centered at 38°N, 55°W as part of the eastern array of the SYNOP (SYNoptic Ocean Prediction) Experiment. The region of focus is one rich in mesoscale energy, with the influence of local Gulf Stream meandering and cold-core ring activity strikingly evident. Daily-averaged acoustic transmissions yielded travel times which were inverted to obtain estimates of range-averaged temperature and current velocity fields, and area-averaged relative vorticity fields. The acoustically determined estimates are consistent with nearby current meter measurements and satellite infrared imagery. The signature of cold-core rings is clearly evident in the sections. Spectral estimates of the fields are dominated by motions with periodicities ranging from 32-128 days. Secondorder statistics, such as eddy kinetic energies, and heat and momentum fluxes, are also estimated. The integrating nature of the tomographic measurement has been exploited to shed some light on the radiation of eddy energy from the Gulf Stream. The Eliassen-Palm flux diagnostic has been applied to an investigation of wave radiation from the Gulf Stream. Results of the diagnosis suggest that the Gulf Stream itself is the source of wave energy radiating into the far field and found in the interior of the North Atlantic subtropical gyre.

show abstract

Section: Introductionmentioning

confidence: 99%

A tomographic view of the Gulf Stream southern recirculation gyre at 38 degrees N, 55 degrees W

Chester¹

1993

Self Cite

View full text Add to dashboard Cite

show abstract

A Review of Ocean Acoustic Tomography: 1987–1990

Worcester

Cornuelle

Spindel

1991

Reviews of Geophysics

View full text Add to dashboard Cite

Research in ocean acoustic tomography during the last quadrennium has resulted in substantial progress in understanding the capabilities and limitations of the technique. Theoretical studies and numerical simulations have led to greater understanding of the oceanographic information available in a vertical slice from acoustic transmissions between a single pair of instruments, of the horizontal geometries required to map the ocean mesoscale field with specified precision, and of the properties of tomographic reconstructions of the two‐dimensional vector field of current. Simultaneously, the instrumentation used in tomographic experiments has been significantly improved, increasing the precision of the measurements and making gyre and basin scale experiments feasible between moored instruments. Experimental efforts to test the accuracy with which the ocean temperature and current fields can be measured acoustically have now demonstrated that tomographic techniques provide measurements with oceanographically useful precision up to ranges of about 1000 km. Such demonstrations are difficult due to the incompatibility between point measurements and the spatial averages provided by tomographic techniques. The experiments have also yielded significant information on the character of acoustic propagation at long range in the ocean. Experimental precision is now adequate to distinguish between competing algorithms for sound speed as a function of temperature, salinity, and depth. Finally, and most importantly, emphasis has shifted to use of the technique for studying the ocean, rather than on understanding the capabilities and limitations of the technique. Two major experiments, the Greenland Sea Tomography Experiment and the Gulf Stream Extension Tomography Experiment, both conducted during 1988–89, were devoted to improving our understanding of ocean dynamics, although results are not yet available. There is increased emphasis on exploiting the integrating nature of acoustic transmissions to study gyre and global scale temperature variability, phenomena difficult to study in any other way.

show abstract

Acoustic tomography in the Straits of Florida

Chester¹,

Malanotte‐Rizzoli²,

DeFerrari³

1991

J. Geophys. Res.

View full text Add to dashboard Cite

Variability of the Florida Current has been monitored via acoustic tomography. A reciprocal tomography experiment was conducted in the eastern half of the Florida Straits during mid‐October and November, 1983. A triangular array of transceivers, with leg separations of approximately 45 km, was deployed at 27°N. The presence of a surface mixed layer in the region allowed for the ducted propagation of acoustic energy in the surface layer. A deeper layer was sampled by an unresolved group of refracted, bottom‐reflected ray arrivals. Incorporating the complete set of arrivals, we are able to obtain depth‐dependent estimates of the temperature field, current velocity, and relative vorticity. The oceanography of the region has been shown to be dominated by the lateral shifting of the surface and subsurface core of the Florida Current. The influx of westward flowing water through the Northwest Providence Channel at 26°N also appears as a large‐scale signal in the eastern Florida Straits. Low‐frequency fluctuations of temperature, current velocity, and vorticity occur at periods ranging from several days to nearly 2 weeks, and are intimately related to meandering of the Florida Current system.

show abstract

Acoustic tomography in the Straits of Florida

Cited by 3 publications

References 14 publications

A tomographic view of the Gulf Stream southern recirculation gyre at 38 degrees N, 55 degrees W

A tomographic view of the Gulf Stream southern recirculation gyre at 38 degrees N, 55 degrees W

A Review of Ocean Acoustic Tomography: 1987–1990

Acoustic tomography in the Straits of Florida

Contact Info

Product

Resources

About