Dust‐induced episodic phytoplankton blooms in the Arabian Sea during winter monsoon. Issue 10 (27th October 2014)

• Record Type: Journal Article
• Authors: Banerjee, Priyanka; Prasanna Kumar, S.
• Is Part Of: Journal of geophysical research. Volume 119:Issue 10(2014:Oct.)
• Page Start: 7123
• Page End: 7138
• Publication Date: 2014-10-27
• Subjects: Oceanography -- Periodicals; 551.4605
• DOI: 10.1002/2014JC010304
• Languages: English
• ISSNs: 2169-9275

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>Phytoplankton blooms mediated by the oceanic supply of nutrients is a well‐understood phenomenon in the Arabian Sea (AS), while the role of dust deposition in enhancing phytoplankton is less explored. In this paper, we show that during winter monsoon the central Arabian Sea (CAS), away from the realm of active winter convection, supports episodic phytoplankton blooms. These blooms cannot be fully explained by the oceanic input of nutrients through processes such as advection and mixing in the upper ocean. Using satellite images, we tracked about 45 dust storms over the AS during the winter monsoons of 2002–2003 to 2010–2011 of which only eight were followed by chlorophyll enhancements. We used a regional climate model to get possible fluxes of dust and the amount of nutrients (nitrate, phosphate, and iron) that can be derived from the dust depositions. Additionally, we used published in situ nutrients data in conjunction with carbon: nitrogen: phosphorus and iron: carbon molar ratios to compute the potential requirements of different nutrients for the eight cases of chlorophyll enhancements. It is likely that the deepening of the mixed layer can incorporate nitrate and phosphate, but not enough iron from the subsurface waters leading to potential iron limitation. Although, all the phytoplankton blooms within CAS were observed following episodic dust events, only four blooms can be attributed to dust depositions. Our work shows that phytoplankton blooms fueled by episodic dust storms are important in driving the interannual variability in chlorophyll in a region away from active winter convection.</p> </abstract>