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Consequences of inhibition of mixed-layer deepening by the West India coastal current for winter phytoplankton bloom in the northeastern Arabian Sea

DRS at CSIR-National Institute of Oceanography

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Title Consequences of inhibition of mixed-layer deepening by the West India coastal current for winter phytoplankton bloom in the northeastern Arabian Sea
 
Creator Vijith, V.
Vinayachandran, P.N.
Thushara, V.
Amol, P.
Shankar, D.
Anil, A.C.
 
Subject Aquatic communities
Oceanography and limnology
Oceanography and limnology
 
Description The intense winter phytoplankton bloom during November-February in the northeastern Arabian Sea (NEAS) was thought, until recently, to be controlled only by a convective deepening of the mixed layer (ML) owing to cool and dry northeasterlies. But a recent study has shown that the deepening of the ML in the southern NEAS is inhibited by the poleward advection of low-salinity water from the south by the West India Coastal Current (WICC). Using an Ocean General Circulation Model coupled with an ecosystem model, we investigate the consequences of the inhibition of mixed-layer deepening for winter phytoplankton bloom in the NEAS. We show that, during the winter monsoon, the shallow ML inhibits the entrainment of nutrients in the southern NEAS. Strong (weak) positive nitrate tendency in the northern (southern) NEAS seen in the model during the winter monsoon is maintained by strong (weak) entrainment. As a result, the chlorophyll integrated to 200 m depth from the surface is lower in the southern NEAS than in the northern NEAS. The inhibition of mixed-layer deepening in the south affects the size-based distribution of small and large phytoplankton, nutrient limitation terms and growth rate, and their elemental composition. The WICC, which inhibits the deepening of the ML and affects the winter bloom in the NEAS, is driven by coastal Kelvin waves generated by remote winds. This paper demonstrates a mechanism by which remotely forced coastal Kelvin waves impact the biology in the north Indian Ocean
 
Date 2016-12-02T11:41:59Z
2016-12-02T11:41:59Z
2016
 
Type Journal Article
 
Identifier Journal of Geophysical Research: Oceans, vol.121(9); 2016; 6583-6603
http://drs.nio.org/drs/handle/2264/5047
 
Language en
 
Rights Copyright [2016]. All efforts have been made to respect the copyright to the best of our knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.
 
Publisher American Geophysical Union