International Journal of Oceans and Oceanography

Open Access Open Access  Restricted Access Subscription Access
Open Access Open Access Open Access  Restricted Access Restricted Access Subscription Access

Observed Thermal Inversions and Associated Oceanographic Features in the Coastal Waters off North East Coast of India


Affiliations
1 Naval Physical and Oceanographic Laboratory (NPOL), Thrikkakara, Cochin-682 021, India
2 DHI-NTU Research Centre, DHI Water and Environment, 200, Pandan Loop, Pantech-21, Singapore 128388, Singapore
3 Cochin University of Science & Technology (CUSAT), Kochi-682 016, India
     

   Subscribe/Renew Journal


During one of the ongoing scientific missions in December 2000 off Paradeep, north-east coast of India various oceanographic and meteorological observations were made from a time-series location beside the selected spatial locations. The measurements off Paradeep revealed that the tidal effect was very prominent in the coastal region with significant changes in the flow pattern, variations in temperature, salinity and sound speed both in space and time. One of the most important features observed during the experiment was the temperature inversion of 1.5 to 4°C which was consistently present throughout the time-series as well as spatial observations. Generally, such inversions are not observed in other parts of the World Oceans. Measured currents clearly indicated the tidal reversals and spatial variations in the flow pattern. The salinity gradually increased from the coast to deep waters (i.e. about 22 PSU to 32 PSU) within a distance of 60 miles. Winds were low varying between 2 to 5 m/s and the predominant wind direction during the observation period was north-east. The sea-state generally remained calm with wave height varying between 0.2 and 0.6m (fair weather season). Tidal influence up to a depth of 50m appeared to be very prominent with its semidiurnal reversal both in magnitude as well as direction. Current speed varied between 0.1 m/s to 0.6 m/s and the predominant direction near to coast was south-west. The inversion layer moved from the surface towards deeper waters during the time-series observations. This might be due to the changes in tidal circulation pattern during the lunar cycle. The measurements during this scientific mission also suggested a salinity front in the upper layers which was extending from the coast up to 40 km offshore.

Keywords

Thermal Inversion, Tidal Reversal, Nearshore Hydrodynamics, Measurements off Paradeep, Observations North-east Coast of India.
Subscription Login to verify subscription
User
Notifications
Font Size


  • Thadathil, P., and Gosh, A. K., 1992, “Surface layer temperature inversion in the Arabian Sea during winter,” J. Oceanogr., 48, 293–304.

  • Thadathil, P., Gopalakrishna, V. V., Muraleedharan, P. M., Reddy, G. V., Araligidad, N. and Shenoy, S., 2002, “Surface layer temperature inversion in the Bay of Bengal,” Deep Sea Res. Part I, 49, 1801–1818.

  • Vinayachandran, P. N., Murty, V. S. N., and Ramesh, Babu, V., 2002, “Observations of barrier layer formation in the Bay of Bengal during summer monsoon,” J. Geophys. Res., 107.

  • Thompson, Bijoy., Gnannaseelan., and Salvekar, P. S., 2006, “Seasonal evolution of temperature inversions in the north Indian Ocean,” Current Science,” 90(5), 697-704.

  • Lozier, M. S., McCartney, M. S., and Owens, W. B., 1994, “Anomalous anomalies in averaged hydrographic data,” J. Phys. Oceanogr., 24, 2624–2638.

  • Masson, S., Delecluse, P., Boulager, J. P., and Menkes, C., 2002, “A model study of the seasonal variability and formation mechanisms of the barrier layer in the equatorial Indian Ocean,” J. Geophys. Res., 107(C12), 8017, doi:10.1029/2001JC000832.

  • Panakala, Rao, D., and Sastry, J. S., 1981, “Circulation and distribution of some hydrographical properties during the late winter in the Bay of Bengal, Mahasagar,” Bull. Nat. Inst. Oceanogr., 14, 1–15.

  • Shetye, S. R., Gouveia, A. D., Shenoi, S. S. C.,Michael, G. S., Sunder, D., Almeida, A. M., and Santanam, K., 1991, “The coastal current of western India during the northeast monsoon,” Deep-Sea Res., 38, 1517– 1529.

  • Shetye, S. R., Gouveia, A. D., Shenoi, S. S. C., Vinayachandran, P. N., Sundar, D., Michael, G. S. and Namboothiri, G., 1996, “Hydrography and circulation in the western Bay of Bengal during the north east monsoon,” J. Geophys. Res., 101, 14011–14025.

  • Sprintall, J. and Tomczak, M., 1992, “Evidence of the barrier layer in the surface layer of the tropics.” J. Geophys. Res., 97, 7305– 7316.

  • Wyrtky, K., 1971, Oceanographic Atlas of the International Indian Ocean Expedition. US Government Printing Office, Washington DC.

  • Levitus, S., and Boyer, T., 1994, Temperature, vol. 4, World Ocean Atlas, 117 pp., NOAA, Washington D. C.

  • Surveyor General of India, 2000, Indian Tide Table Part-I, Printing Group of Survey of India, Dehra Dun.

  • Hastenrath, S., and Lamb, P. J., 1979, Climatic atlas of the Indian Ocean, Part-I, Surface Climate and Atmospheric Circulation, The University of Wisconsin Press, USA.

  • Young, I. R., and Holland, G. J., 1996, Atlas of the Oceans: Wind and Wave Climate, Pergamon, Elsevier Science, USA.

  • Kjerfve, B., 1988, Hydrodynamics of Estuaries, Volume II, Estuarine Case Studies, CRC Press, Inc., Boca Raton, Florida.


Abstract Views: 509

PDF Views: 0




  • Observed Thermal Inversions and Associated Oceanographic Features in the Coastal Waters off North East Coast of India

Abstract Views: 509  |  PDF Views: 0

Authors

J. Swain
Naval Physical and Oceanographic Laboratory (NPOL), Thrikkakara, Cochin-682 021, India
P. A. Umesh
Naval Physical and Oceanographic Laboratory (NPOL), Thrikkakara, Cochin-682 021, India
J. K. Panigrahi
DHI-NTU Research Centre, DHI Water and Environment, 200, Pandan Loop, Pantech-21, Singapore 128388, Singapore
A. N. Balchand
Cochin University of Science & Technology (CUSAT), Kochi-682 016, India

Abstract


During one of the ongoing scientific missions in December 2000 off Paradeep, north-east coast of India various oceanographic and meteorological observations were made from a time-series location beside the selected spatial locations. The measurements off Paradeep revealed that the tidal effect was very prominent in the coastal region with significant changes in the flow pattern, variations in temperature, salinity and sound speed both in space and time. One of the most important features observed during the experiment was the temperature inversion of 1.5 to 4°C which was consistently present throughout the time-series as well as spatial observations. Generally, such inversions are not observed in other parts of the World Oceans. Measured currents clearly indicated the tidal reversals and spatial variations in the flow pattern. The salinity gradually increased from the coast to deep waters (i.e. about 22 PSU to 32 PSU) within a distance of 60 miles. Winds were low varying between 2 to 5 m/s and the predominant wind direction during the observation period was north-east. The sea-state generally remained calm with wave height varying between 0.2 and 0.6m (fair weather season). Tidal influence up to a depth of 50m appeared to be very prominent with its semidiurnal reversal both in magnitude as well as direction. Current speed varied between 0.1 m/s to 0.6 m/s and the predominant direction near to coast was south-west. The inversion layer moved from the surface towards deeper waters during the time-series observations. This might be due to the changes in tidal circulation pattern during the lunar cycle. The measurements during this scientific mission also suggested a salinity front in the upper layers which was extending from the coast up to 40 km offshore.

Keywords


Thermal Inversion, Tidal Reversal, Nearshore Hydrodynamics, Measurements off Paradeep, Observations North-east Coast of India.

References