Wind-induced upwelling in the Kerguelen Plateau region
In contrast to most of the Southern Ocean, the Kerguelen Plateau supports an unusually strong spring chlorophyll (Chl ia) bloom, likely because the euphotic zone in the region is supplied with higher iron concentrations. This study uses satellite wind, sea surface temperature (SST), and ocean color...
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ftcdlib:oai:escholarship.org/ark:/13030/qt894704nk 2023-05-15T17:02:09+02:00 Wind-induced upwelling in the Kerguelen Plateau region Gille, ST Carranza, MM Cambra, R Morrow, R 6389 - 6400 2014-11-26 https://escholarship.org/uc/item/894704nk unknown eScholarship, University of California qt894704nk https://escholarship.org/uc/item/894704nk public Biogeosciences, vol 11, iss 22 Meteorology & Atmospheric Sciences Earth Sciences Environmental Sciences Biological Sciences article 2014 ftcdlib 2021-04-16T07:11:40Z In contrast to most of the Southern Ocean, the Kerguelen Plateau supports an unusually strong spring chlorophyll (Chl ia) bloom, likely because the euphotic zone in the region is supplied with higher iron concentrations. This study uses satellite wind, sea surface temperature (SST), and ocean color data to explore the impact of wind-driven processes on upwelling of cold (presumably iron-rich) water to the euphotic zone. Results show that, in the Kerguelen region, cold SSTs correlate with high wind speeds, implying that wind-mixing leads to enhanced vertical mixing. Cold SSTs also correlate with negative wind-stress curl, implying that Ekman pumping can further enhance upwelling. In the moderate to high eddy kinetic energy (EKE) regions surrounding Kerguelen, we find evidence of coupling between winds and SST gradients associated with mesoscale eddies, which can locally modulate the wind-stress curl. This coupling introduces persistent wind-stress curl patterns and Ekman pumping around these long-lived eddies, which may modulate the evolution of Chl ia in the downstream plume far offshore. Close to the plateau, this eddy coupling breaks down. Kerguelen has a significant wind shadow on its downwind side, which changes position depending on the prevailing wind and which generates a wind-stress curl dipole that shifts location depending on wind direction. This leads to locally enhanced Ekman pumping for a few hundred kilometers downstream from the Kerguelen Plateau; Chl ia values tend to be more elevated in places where wind-stress curl induces Ekman upwelling than in locations of downwelling, although the estimated upwelling rates are too small for this relationship to derive from direct effects on upward iron supply, and thus other processes, which remain to be determined, must also be involved in the establishment of these correlations. During the October and November (2011) KErguelen Ocean and Plateau compared Study (KEOPS-2) field program, wind conditions were fairly typical for the region, with enhanced Ekman upwelling expected to the north of the Kerguelen Islands. Article in Journal/Newspaper Kerguelen Islands Southern Ocean University of California: eScholarship Southern Ocean Kerguelen Kerguelen Islands Curl ENVELOPE(-63.071,-63.071,-70.797,-70.797) |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Meteorology & Atmospheric Sciences Earth Sciences Environmental Sciences Biological Sciences |
spellingShingle |
Meteorology & Atmospheric Sciences Earth Sciences Environmental Sciences Biological Sciences Gille, ST Carranza, MM Cambra, R Morrow, R Wind-induced upwelling in the Kerguelen Plateau region |
topic_facet |
Meteorology & Atmospheric Sciences Earth Sciences Environmental Sciences Biological Sciences |
description |
In contrast to most of the Southern Ocean, the Kerguelen Plateau supports an unusually strong spring chlorophyll (Chl ia) bloom, likely because the euphotic zone in the region is supplied with higher iron concentrations. This study uses satellite wind, sea surface temperature (SST), and ocean color data to explore the impact of wind-driven processes on upwelling of cold (presumably iron-rich) water to the euphotic zone. Results show that, in the Kerguelen region, cold SSTs correlate with high wind speeds, implying that wind-mixing leads to enhanced vertical mixing. Cold SSTs also correlate with negative wind-stress curl, implying that Ekman pumping can further enhance upwelling. In the moderate to high eddy kinetic energy (EKE) regions surrounding Kerguelen, we find evidence of coupling between winds and SST gradients associated with mesoscale eddies, which can locally modulate the wind-stress curl. This coupling introduces persistent wind-stress curl patterns and Ekman pumping around these long-lived eddies, which may modulate the evolution of Chl ia in the downstream plume far offshore. Close to the plateau, this eddy coupling breaks down. Kerguelen has a significant wind shadow on its downwind side, which changes position depending on the prevailing wind and which generates a wind-stress curl dipole that shifts location depending on wind direction. This leads to locally enhanced Ekman pumping for a few hundred kilometers downstream from the Kerguelen Plateau; Chl ia values tend to be more elevated in places where wind-stress curl induces Ekman upwelling than in locations of downwelling, although the estimated upwelling rates are too small for this relationship to derive from direct effects on upward iron supply, and thus other processes, which remain to be determined, must also be involved in the establishment of these correlations. During the October and November (2011) KErguelen Ocean and Plateau compared Study (KEOPS-2) field program, wind conditions were fairly typical for the region, with enhanced Ekman upwelling expected to the north of the Kerguelen Islands. |
format |
Article in Journal/Newspaper |
author |
Gille, ST Carranza, MM Cambra, R Morrow, R |
author_facet |
Gille, ST Carranza, MM Cambra, R Morrow, R |
author_sort |
Gille, ST |
title |
Wind-induced upwelling in the Kerguelen Plateau region |
title_short |
Wind-induced upwelling in the Kerguelen Plateau region |
title_full |
Wind-induced upwelling in the Kerguelen Plateau region |
title_fullStr |
Wind-induced upwelling in the Kerguelen Plateau region |
title_full_unstemmed |
Wind-induced upwelling in the Kerguelen Plateau region |
title_sort |
wind-induced upwelling in the kerguelen plateau region |
publisher |
eScholarship, University of California |
publishDate |
2014 |
url |
https://escholarship.org/uc/item/894704nk |
op_coverage |
6389 - 6400 |
long_lat |
ENVELOPE(-63.071,-63.071,-70.797,-70.797) |
geographic |
Southern Ocean Kerguelen Kerguelen Islands Curl |
geographic_facet |
Southern Ocean Kerguelen Kerguelen Islands Curl |
genre |
Kerguelen Islands Southern Ocean |
genre_facet |
Kerguelen Islands Southern Ocean |
op_source |
Biogeosciences, vol 11, iss 22 |
op_relation |
qt894704nk https://escholarship.org/uc/item/894704nk |
op_rights |
public |
_version_ |
1766055411098583040 |