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Atmospheric deposition and surface stratification as controls of contrasting chlorophyll abundance in the North Indian Ocean

DRS at CSIR-National Institute of Oceanography

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Title Atmospheric deposition and surface stratification as controls of contrasting chlorophyll abundance in the North Indian Ocean
 
Creator Patra, P.K.
DileepKumar, M.
Mahowald, N.
Sarma, V.V.S.S.
 
Subject Arabian Sea
Bay of Bengal
Biological productivity
Atmospheric deposition
 
Description Intense upwelling during summer and convection in winter are believed to drive higher biological productivity in the Arabian Sea than in the Bay of Bengal. Although the Arabian Sea receives substantial atmospheric deposition of dust aerosols, its role in biological activity is unknown. We have analyzed chlorophyll-a (SeaWiFS), absorbing aerosol index (TOMS), surface winds (NCEP), and modeled dust deposition and SST (OI) data during two distinct seasons June– August (JJA, summer months) and October–December (OND, winter months) for the period 1997– 2004. Climatologies of physicochemical properties have been developed from World Ocean Atlas 2001 (WOA01). Our results suggest that despite the strong vertical supply of nutrients in the western and central Arabian Sea regions, maximal chlorophyll-a was limited to the former region in both JJA and OND periods, suggesting the importance of atmospherically transported substances in determining chlorophyll abundance in the North Indian Ocean. Time-averages (1997-2004) revealed chlorophyll abundances in northwestern regions are larger than in other regions of the respective basins. The NW regions of the Arabian Sea and the Bay of Bengal have exhibited contrasting chlorophyll distribution patterns during El Niño years (1997-98 and 2002-03; positive SST anomalies); decreased and increased chlorophyll contents in respective regions. Following the passage of tropical cyclones, SeaWiFS records depicted large areas in the Arabian Sea to experience intensified chlorophyll production with strong wind speeds of 55-65 knots whereas its enhanced production occurred only in small patches even under the influence of Orissa Super Cyclone of October 1999 (wind speed up to 140 knots) due to strong stratification.
 
Date 2007-05-22T09:47:54Z
2007-05-22T09:47:54Z
2007
 
Type Journal Article
 
Identifier Journal of Geophysical Research, (C: Oceans), vol.112(5), C05029
http://drs.nio.org/drs/handle/2264/614
 
Language en
 
Rights An edited version of this paper was published by AGU. Copyright [2007] AGU. To view the published open abstract, go to http://dx.doi.org and enter the DOI.
 
Format 1788484 bytes
application/pdf
 
Publisher American Geophysical Union