• Fulltext

       

        Click here to view fulltext PDF


      Permanent link:
      https://www.ias.ac.in/article/fulltext/jess/130/0077

    • Keywords

       

      Eastern boundary currents; ADCP; seasonal variability; intraseasonal variability; continental shelf; WICC; Arabian Sea; Indian Ocean.

    • Abstract

       

      We describe the variability of the West India Coastal Current (WICC) during 2009–2017 using data from acoustic Doppler current profilers (ADCPs) attached to moorings deployed on the outer shelf at a water-column depth of 100–200 m at three locations: off Kollam (9$^{\circ}$N), Bhatkal (13.9$^{\circ}$N), and Goa (15$^{\circ}$N). Our study shows that the characteristics of the WICC on the outer shelf are similar to those observed on the slope except for the occasional decorrelation observed between them. Both shelf and slope WICC have a weak mean flow and a strong annual cycle. As seen on the slope, the depth of the undercurrent on the shelf changes with season because of the strong upward phase propagation associated with the annual cycle. Though the currents at all three shelf locations exhibit a strong seasonal cycle, there are prominent differences between the currents off the southwest coast of India (Kollam) and the central west coast of India (Bhatkal and Goa). The seasonal cycle off Kollam is often punctuated by strong intraseasonal bursts, which cause the shelf WICC off Kollam to be highly unpredictable; this unpredictability implies that on a given day of the year, one cannot expect a poleward (equatorward) current during the winter (summer) monsoon. On the central west coast, the poleward (equatorward) direction during the winter monsoon (summer monsoon) is prominent. Comparison with the available datasets shows that the WICC is occasionally coherent along and across the shelf, and the coherence is stronger for the seasonal cycle.

      $\bf{Highlights}$

      $\bullet$ Characteristics of the WICC on the outer shelf are similar to those observed on the slope.

      $\bullet$ Shelf WICC has a weak mean flow and a strong annual cycle.

      $\bullet$ Differences observed between currents off central west coast and southwest coast of India.

      $\bullet$ Seasonal cycle off Kollam is often punctuated by strong intraseasonal bursts.

    • Author Affiliations

       

      ANYA CHAUDHURI1 AMOL P2 SHANKAR D1 MUKHOPADHYAY S1 3 APARNA S G1 FERNANDO V1 A KANKONKAR1

      1. CSIR-National Institute of Oceanography, Dona Paula, Goa, India.
      2. CSIR-National Institute of Oceanography Regional Centre, Visakhapatnam, India.
      3. Indian Institute of Tropical Meteorology, Pune, India.
    • Dates

       
    • Supplementary Material

       
  • Journal of Earth System Science | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2021-2022 Indian Academy of Sciences, Bengaluru.