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<p>The circulation in the western Bay of Bengal (BoB), with its seasonal reversing component known as the East Indian Coastal Current (EICC), has complex spatial and temporal dynamics. This study estimates the contribution of various diagnostic processes to the power spectrum of observed currents in the western BOB, using data from three ground-based High-Frequency Radars (HFR), as well as satellite-derived currents (SDC) and data from the Global Ocean Forecast System (GOFS). The current spectra associated with three datasets show good agreement between them across all measurement stations, exhibiting distinct peaks at a number of intra-seasonal, seasonal and sub-seasonal harmonics with the annual and semi-annual components dominating. HFR spectra are 10-15% less energetic than SDC spectra, and 20-25% more energetic than GOFS spectra. Analysis of the Ekman (wind-driven) and geostrophic currents reveals that the local winds contribute 20-35% of the energy in the short-period intraseasonal harmonics with periodicity ranging between 20-60 days, and 10-25% in the long-period intraseasonal and seasonal harmonics. A large portion of the observed currents, ranging from 65% to 82%, results from geostrophic balance, suggesting a strong connection between the nearshore current system and basin-scale atmospheric forcing and associated ocean transport processes. The seasonal reconstruction of the SDC in the western BoB effectively captures the known characteristics of the EICC, which explains up to 35% of the variance of the total currents near Sri Lanka, Tamil Nadu, and the northwestern BoB, while accounting for only up to 15% in other areas of the western BoB. The monsoon and post-monsoon stratification of the oceans in the coastal domain has a negligible impact on enhancing the energetics of the currents throughout the spectrum.</p>

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A diagnostics of observed surface currents in the Western Bay of Bengal using ground based high frequency radar, satellite and model data

  • 期刊论文

  • 发表日期：

    2026年3月3日

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  • Shashank Kumar Mishra,
  • Rabindra Kumar Nayak,
  • Prakash Chandra Mohanty,
  • Rajesh Sikhakolli,
  • G. Srinivasa Rao,
  • Prakash Chauhan

摘要

The circulation in the western Bay of Bengal (BoB), with its seasonal reversing component known as the East Indian Coastal Current (EICC), has complex spatial and temporal dynamics. This study estimates the contribution of various diagnostic processes to the power spectrum of observed currents in the western BOB, using data from three ground-based High-Frequency Radars (HFR), as well as satellite-derived currents (SDC) and data from the Global Ocean Forecast System (GOFS). The current spectra associated with three datasets show good agreement between them across all measurement stations, exhibiting distinct peaks at a number of intra-seasonal, seasonal and sub-seasonal harmonics with the annual and semi-annual components dominating. HFR spectra are 10-15% less energetic than SDC spectra, and 20-25% more energetic than GOFS spectra. Analysis of the Ekman (wind-driven) and geostrophic currents reveals that the local winds contribute 20-35% of the energy in the short-period intraseasonal harmonics with periodicity ranging between 20-60 days, and 10-25% in the long-period intraseasonal and seasonal harmonics. A large portion of the observed currents, ranging from 65% to 82%, results from geostrophic balance, suggesting a strong connection between the nearshore current system and basin-scale atmospheric forcing and associated ocean transport processes. The seasonal reconstruction of the SDC in the western BoB effectively captures the known characteristics of the EICC, which explains up to 35% of the variance of the total currents near Sri Lanka, Tamil Nadu, and the northwestern BoB, while accounting for only up to 15% in other areas of the western BoB. The monsoon and post-monsoon stratification of the oceans in the coastal domain has a negligible impact on enhancing the energetics of the currents throughout the spectrum.