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Observational evidence of upwelling off the southwest coast of India during June-July 2006

DRS at CSIR-National Institute of Oceanography

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Title Observational evidence of upwelling off the southwest coast of India during June-July 2006
 
Creator Lekshmi, S.
Smitha, B.R.
Revichandran, C.
 
Subject coastal upwelling
latitudinal variations
river discharge
runoff
temperature
salinity
 
Description Considerable latitudinal variability exists in the forcing mechanisms and intensity of coastal upwelling along the southwest coast of India. Present work is based on the insitu observations conducted onboard FORV Sagar Sampada for 12 days along two transects off Thiruvananthapuram (8.5 degrees N) and off Koilam (9 degrees N), during June 25th-6th July 2006. Observed upwelling parameters (local temperature anomalies, salinity, isothermal layer depth (ILD), Mixed Layer Depth (MLD), isotherm slope, nutrients) are examined with reference to the Jocal forcing along the two transects. In addition, the day-to-day variations in the vertical distribution of different oceanographic parameters are also documented. During the period of observation, wind was predominantly north northwesterly. The alongshore component of the wind stress (local forcing) is weaker off Koilam (0.1-0.5 dynes/cm sup(2)) compared to that off Thiruvananthapuram (0.3-1.0 dynes/cm sup(2)). However, the observed upwelling parameters are not in tune with the local forcings. ILD off Koilam (11-17 m) is shallower than that off Thiruvananthapuram (18-21 m). If the observed upwelling is forced by local wind, then the ILD off Koilam should shoal less compared to that off Thiruvananthapuram. Other upwelling parameters (isotherm slope towards the coast and local cooling) also reveal this contrast between local forcing and observed upwelling. The surface salinity off Koilam is comparatively lower (30.8-33.8 PSG) to that off Thiruvananthapuram (34-34.6 PSU) with significant difference in vertical stratification. The runoff data during the observation period support the surface salinity distribution. High precipitation off Koilam also has a significant role in determining the surface water characteristics (Temperature and Salinity).
 
Date 2008-01-31T11:21:58Z
2008-01-31T11:21:58Z
2007
 
Type Conference Article
 
Identifier METOC - 2007. Proceedings of the National Symposium on 'Emerging Tredns in Meteorology and Oceanography', 21-22 May 2007, eds. Vijayakumar, D.; Jothiraman, V.; Jyothi, A.K.; Satya Prakash; Krishna, M.S.H. 203-207p.
http://drs.nio.org/drs/handle/2264/796
 
Language en
 
Publisher School of Naval Oceanology and Meteorology