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Monsoonal and ENSO impacts on particle fluxes and the biological pump in the Indian Ocean

DRS at CSIR-National Institute of Oceanography

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Title Monsoonal and ENSO impacts on particle fluxes and the biological pump in the Indian Ocean
 
Creator Rixen, T.
Ramaswamy, V.
Gaye, B.
Herunadi, B.
Maier-Reimer, E.
Bange, H.W.
Ittekkot, V.
 
Subject particle fluxes
Indian Ocean
oxygen minimum zones
biogeochemical fluxes
 
Description Data obtained by sediment trap experiments in the Indian Ocean were evaluated in conjunction with additional information derived mainly from the Joint Global Ocean Flux Study (JGOFS) expeditions in 1994/1995. Our results indicate that wind-driven upwelling, thermohaline mixing, and freshwater inputs are the main physical processes through which the monsoon drives the biogeochemical fluxes in the Indian Ocean. The upwelling system in the Arabian Sea seems to be bottom-up controlled and very sensitive to iron supply affecting system immanent threshold concentrations and to nitrate reduction rates in the mid-water oxygen minimum zones (OMZs). On geologic timescales, nitrate reduction rates were strongly linked to Northern Hemispheric climate variations, whereby the thermohaline mixing and the associated mid-water formation in the northern Arabian Sea could have played a key role. The ratios between organic and inorganic carbon of particles exported from the surface ocean indicate that the biologically mediated CO sub(2) uptake, referred to as the biological pump, is low in the Arabian Sea during the high productive upwelling period. The biological pump seems to be strongest along the freshwater-influenced continental margins in the eastern Indian Ocean where the climate anomaly El Nino-Southern Oscillation (ENSO) influences the biological pump by its impact on the precipitation rates and the river discharges. Associated physical processes such as the capping effect amplify the ENSO impact on the CO sub(2) degassing, whereby ENSO increases/decreases the CO sub(2) degassing into the atmosphere in its negative (El Nino) and positive mode (La Nina)
 
Date 2010-01-12T07:16:26Z
2010-01-12T07:16:26Z
2009
 
Type Book Chapter
 
Identifier In "Indian Ocean biogeochemical processes and ecological variability. eds. by: Wiggert, J.D.; Hood, R.R.; Naqvi, S.W.A.; Brink, K.H.; Smith, S.L.", 365-383p.
http://drs.nio.org/drs/handle/2264/3529
 
Language en
 
Rights Copyright [2009] AGU. 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