Summary of Abstract Submission

Abstract Submission No. IO50-04-0050PresentationPoster

VERTICAL STRUCTURE OF TIDAL AND RESIDUAL CURRENTS IN THE LACCADIVE SEA THROUGH FIELD OBSERVATION

Dr K Rajith*1

1 Naval Physical and Oceanographic Laboratory, Cochin, India

ABSTRACT :

Understanding of Coastal circulation plays an important role in determining the beach stability by controlling the sediment re-suspension and transport. Also it influences the littoral antisubmarine warfare operations and mine hunting operations. Tide plays an important role in determining the coastal circulation pattern. A study was conducted off Quilon to understand the importance of tide in determining the coastal circulation. Data on current, tide and wave were collected at a depth of 70m by mooring an upward looking Acoustic Doppler Current Profiler (ADCP). The characteristics of vertical structure of tidal and residual currents are discussed in this work. Current was recorded in every 2 mins with a bin size of 2m. Tide and wave data were collected at 1hr interval and with burst duration of 20minutes. The maximum tidal range was 80cm with mixed semi diurnal characteristics. Wave height was less than a meter with period more than 10s which is typical for fair weather season. Tidal and residual currents were separated using high pass/low pass filters. It was observed that the tidal currents were very weak in this region. Harmonic analysis of tidal current reveals that the semidiurnal component is dominating. The residual current direction was north ward which is in tune with the general circulation pattern prevailing in this area during the month of March. The maximum speed of this current was up to 1m/s in the surface layers. Vertical variability of residual current was less. The tidal response on current varies with depth. Our result indicates that, tide plays less role in controlling the prevailing circulation pattern in the study area.