HR: 1340h
AN: OS13A-1017    [Abstracts]
TI: Long-Range Propagation of Semidiurnal Internal Tides in the North Pacific Ocean
AU: * Zhao, Z
EM: zzhao@apl.washington.edu
AF: Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105, United States
AU: Alford, M H
EM: malford@apl.washington.edu
AF: Applied Physics Laboratory and School of Oceanography, University of Washington, 1013 NE 40th Street, Seattle, WA 98105, United States
AB: Internal tides provide a major energy source to drive the oceanic meridional overturning circulation, whose variation has profound implications for global climate change. In the North Pacific Ocean, the long-range propagation of semidiurnal internal tides is studied using field moorings and TOPEX/Poseidon (T/P) altimeter data. Moorings, at the cost of greatly reduced spatial coverage, can detect both the coherent and incoherent internal tides. T/P altimeter data have continuous global coverage, but can only detect the coherent internal tides. In this study, we develop a phase adjustment method (different from the conventional harmonic analysis) to extract internal tides from the altimeter data. This new method and the use of both the original and tandem T/P along-track data allow us to 1) separate the southward and northward internal tides, and 2) identify narrow internal-tide beams as a result of the improved spatial resolution. These results reveal a new view of the internal-tide field in the North Pacific Ocean. Internal-tide beams can propagate a longer distance than previously thought. Two northward beams radiating from the Hawaiian Ridge propagate across the North Pacific Ocean (more than 3000 km) and reach the Alaskan shelf. The originally overlapped southward Aleutian beams and northward Hawaiian beams are separately resolved. The discrepancies between previous altimetric and moored fluxes are also reduced, indicating that the low spatial resolution and temporal incoherence were the causes.
DE: 4262 Ocean observing systems
DE: 4275 Remote sensing and electromagnetic processes (0689, 2487, 3285, 4455, 6934)
DE: 4544 Internal and inertial waves
DE: 4568 Turbulence, diffusion, and mixing processes (4490)
DE: 4594 Instruments and techniques
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting