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The unusual surface chlorophyll signatures of Southern Ocean eddies

Citation

Dawson, HRS and Strutton, PG and Gaube, P, The unusual surface chlorophyll signatures of Southern Ocean eddies, Journal of Geophysical Research: Oceans, 123, (9) pp. 6053-6069. ISSN 2169-9275 (2018) [Refereed Article]


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Copyright Statement

Copyright 2018 American Geophysical Union

DOI: doi:10.1029/2017JC013628

Abstract

Southern Ocean mesoscale eddies play an important role in ocean circulation and biogeochemical cycling, but their biological characteristics have not been well quantified at the basin scale. To address this, we combined a 15‐year tracked eddy data set with satellite observations of ocean color, sea surface temperature, and autonomous profiling floats to quantify the surface and subsurface properties of eddies. Anomalies of surface temperature and chlorophyll were examined in eddy‐centric composite averages constructed from thousands of eddies. Normalized surface chlorophyll anomalies (chlnorm) vary seasonally and geographically. Cyclones typically show positive chlnorm, while anticyclones have negative chlnorm. The sign of chlnorm reverses during late summer and autumn for eddies between the Subtropical and Polar Fronts. The reversal is most obvious in the Indian sector, and we attribute this to a combination of eddy stirring (deformation of surface gradients by the rotational velocity of an eddy) and deeper winter mixing in anticyclones. Both chlnorm and sea surface temperature anomalies transition from dipole structures north of the Subtropical Front to monopole structures south of the Subantarctic Front. Sea surface temperature and chlnorm composites provide evidence for eddy trapping (transporting of anomalies) and eddy stirring. This research provides a basin‐scale study of surface chlorophyll in Southern Ocean eddies and reveals counterintuitive biogeochemical signals.

Item Details

Item Type:Refereed Article
Keywords:Southern Ocean, mesoscale, eddies, ocean circulation, biogeochemical cycling, surface chlorophyll, mixed layer depth
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical Oceanography
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Climate Variability (excl. Social Impacts)
UTAS Author:Dawson, HRS (Miss Hannah Dawson)
UTAS Author:Strutton, PG (Associate Professor Peter Strutton)
ID Code:130949
Year Published:2018
Deposited By:Oceans and Cryosphere
Deposited On:2019-02-21
Last Modified:2019-03-12
Downloads:33 View Download Statistics

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