Focal Regions in Spectrograms of Long Range Propagation
Bill Kuperman
Director of Marine Physical Laboratory, Scripps Institution of Oceanography
A source near the deep sound channel axis excites mode groups (or paths) that involve both deep sound channel and boundary interacting propagation. Modal group speeds have a functional transition when crossing through purely refractive to boundary reflecting phase speed regions. The result is that arrivals in this transition region line up in time across frequency; this combined with a similar, though broader coincidence of the last deep sound channel arrivals provide two time markers on a single phone spectrogram (intensity as a function of arrival time and frequency). Indeed, the ATOC data show this effect. These time markers,depending on auxiliary information, provide inversion capability.
Progress in Modal Phase Tomography (MPT) and Modal-Horizontal-Refraction Tomography (MRHT) for Ocean Monitoring
EC Shang
NOAA, Wave Propagation Laboratory
The potential oppertunities of retrieval ocean dynamic structures by using Modal-Phase Tomography (MPT) and Modal-Horizontal-Refraction Tomography (MHRT) are discussed. Four issues are addressed: (1) retrieval of the 3D structure of a strong warm eddy; (2) retrieval of front parameters; (3) retrieval of internal solitary waves in coastal zone; and (4) monitoring of the transverse component of current in Fram Strait.
