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Proceedings Paper

Summer chlorophyll-a distribution in eastern Arabian Sea off Karnataka-Goa coast from satellite and in-situ observations
Author(s): B. R. Raghavan; Mini Raman; P. Chauhan; B. Sunil Kumar; S. K. Shylini; R. S. Mahendra; S. R. Nayak
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Paper Abstract

Chlorophyll-a maps derived from IRS-P4 Ocean Color Monitor (OCM) was used to study the distribution pattern of phytoplankton biomass in the eastern Arabian sea off Karnataka-Goa coast, southwest coast of India. The data was compared with in-situ measurements of chlorophyll-a concentration estimated for 100 stations covering an area of more than 4000 km^2 in the above region. The presence of dense algal blooms spread over an area of almost 100 km^2 representing Trichodesmium sp. 18km off Kumta-Gokarna in the eastern Arabian Sea depicts high value (30 to 40 mg/m^3) of chlorophyll concentration. Similarly, around the Nethrani Island, off Bhatkal, the surface concentration ranged from 5 to 10 mg/m^3. The secchi depth varied from 4 to 8 m near the island. The sea surface area enveloping this high bloom (around the island) depicts a normal distribution of chlorophyll-a ranging from of 0.1 to 5 mg/m^3. It is suggested here, that the low salinity value (35 to 35.2 %) around the Nethrani Island enhances the algal bloom due to enrichment of nutrients in the shallow marine environment through probable inputs of nutrient charged fresh water from the island aquifers. Near river mouths, the values are marginally high in the range of 3 to 5 mg/m^3, probably enforced by riverine nutrient inputs well depicted by the Tadri River. The satellite (IRS-P4 OCM) derived images of chlorophyll during summer also shows high values as a band parallel to the coast. During the occurrence of algal blooms this band, parallel to the coast, widens offshore and this phenomenon of widening is typically absent during non-bloom summer scenarios, as identified for summer 2005.

Paper Details

Date Published: 28 November 2006
PDF: 7 pages
Proc. SPIE 6406, Remote Sensing of the Marine Environment, 64060W (28 November 2006); doi: 10.1117/12.694232
Show Author Affiliations
B. R. Raghavan, Mangalore Univ. (India)
Mini Raman, Space Applications Ctr. (India)
P. Chauhan, Space Applications Ctr. (India)
B. Sunil Kumar, Mangalore Univ. (India)
S. K. Shylini, Mangalore Univ. (India)
R. S. Mahendra, INCOIS (India)
S. R. Nayak, INCOIS (India)

Published in SPIE Proceedings Vol. 6406:
Remote Sensing of the Marine Environment
Robert J. Frouin; Vijay K. Agarwal; Hiroshi Kawamura; Shailesh Nayak; Delu Pan, Editor(s)

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