Optimum Estimation of Coastal Currents Using Moving Vehicles

Kuanyu Chen, Chen Fen Huang*, Zhe Wen Zheng, Sheng Fong Lin, Jin Yuan Liu, Jenhwa Guo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Ocean acoustic tomography (OAT) deploys most moored stations on the periphery of the tomographic region to sense the solenoidal current field. Moving vehicle tomography (MVT), an advancement of OAT, not only samples the region from various angles for improving the resolution of mapped currents but also acquires information about the ir-rotational flow due to the sampling points inside the region. To reconstruct a complete two-dimensional current field, the spatial modes derived from the open-boundary modal analysis (OMA) are preferable to the conventional truncated Fourier series since the OMA technique describes the solenoidal and irrotational flows efficiently in which all modes satisfy the coastline and open boundary conditions. Comparisons of the reconstructions are presented using three different representations of currents. The first two representations explain only the solenoidal flow: the truncated Fourier series and the OMA Dirichlet modes. The third representation, accounting for the solenoidal and irrotational flows, uses all the OMA modes. For reconstructing the solenoidal flow, the OMA representation with the Dirichlet modes performs better than the Fourier series. A large difference appears near the bay mouth, where the OMA-Dirichlet reconstruction shows a better fit to the uniform currents. However, considerable uncertainty exists outside the bay mouth where the irrotational currents dominate. This can be improved by the third representation with the inclusion of the Neumann and boundary modes. The reconstruction results using field data were validated against the acoustic Doppler current profiler (ADCP) measurements. Additionally, incorporating constraints from ADCP measurements enhances the accuracy of the reconstruction.

Original languageEnglish
Pages (from-to)1431-1441
Number of pages11
JournalJournal of Atmospheric and Oceanic Technology
Volume40
Issue number12
DOIs
Publication statusPublished - 2023 Dec

Keywords

  • Acoustic measurements/effects
  • In situ oceanic observations
  • Remote sensing

ASJC Scopus subject areas

  • Ocean Engineering
  • Atmospheric Science

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