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Progress in Modal Phase Tomography (MPT) and Modal-Horizontal-

Refraction Tomography (MHRT) for Ocean Monitoring

 

E.C. Shang1, A.G. Voronovich2, and Y. Y. Wang1

 

1CIRES, University of Colorado/NOAA/Environmental Technology Laboratory, 325 Broadway, Boulder, Colorado, USA. e-mail : eshang@etl.noaa.gov

2Environmental Technology Laboratory, 325 Broadway, Boulder, Colorado, USA

 

ABSTRACT

 

The potential opportunities 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 warrn eddy (Meddy); (2) monitoring of the transverse component of current in Fram Strait; (3) retrieval of front parameters; and (4) retrieval of internal solitary waves in coastal zone.

 

1. INTRODUCTION

 

Recently, the Modal Phase Tomography (MPT) and Modal-Horizontal-Refraction Tomography (MHRT) have been proposed, theoretical and numerical simulation studies have been done [1-4]. One experimental testing of MPT has been conducted in the Norway Sea in 1991, the tomographic inversion of the sound speed in a vertical slice is shown in Fig. 1 [5].

Instead of travel time measurement, modal phase (phase difference) is measured in MPT and MHRT. The wide-band pulse source usedby the time-flight tomography is replaced by a CW source and this is good for low frequency application. Using lower frequency is a possible way to reduce the mode coupling problem and the nonlinear bias problem [6,7].

In this paper, retrieval of the 3D structure of a strong warm eddy by using MHRT is discussed in section 2, monitoring of transverse component of current in the Fram Strait using MHRT is demonstrated in section3. Tomographic inversion of the front and of the internal solitary waves using MPT are discussed in section 4 and 5 respectively. Finally, the concluding remarks are drawing .

 

 

 

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