On the role of atmospheric forcing on upper ocean physics in the Southern Ocean and biological impacts
The Southern Ocean (SO) plays a key role in regulating climate by absorbing nearly half of anthropogenic carbon dioxide (CO$_2$). Both physical and biogeochemical processes contribute to the net CO$_2$ sink. As a result of global warming and ozone depletion, westerly winds have increased, with conse...
Main Author: | |
---|---|
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
eScholarship, University of California
2016
|
Subjects: | |
Online Access: | http://www.escholarship.org/uc/item/5qs1x85p |
id |
ftcdlib:qt5qs1x85p |
---|---|
record_format |
openpolar |
spelling |
ftcdlib:qt5qs1x85p 2023-05-15T18:25:06+02:00 On the role of atmospheric forcing on upper ocean physics in the Southern Ocean and biological impacts Carranza, Magdalena 161 2016-01-01 application/pdf http://www.escholarship.org/uc/item/5qs1x85p en eng eScholarship, University of California http://www.escholarship.org/uc/item/5qs1x85p qt5qs1x85p public Carranza, Magdalena. (2016). On the role of atmospheric forcing on upper ocean physics in the Southern Ocean and biological impacts. UC San Diego: Oceanography. Retrieved from: http://www.escholarship.org/uc/item/5qs1x85p Physical oceanography Biological oceanography Remote sensing atmospheric forcing bio-physical interactions Patagonian shelf satellite chlorophyll-a shelf-break upwelling Southern Ocean dissertation 2016 ftcdlib 2016-12-23T23:51:00Z The Southern Ocean (SO) plays a key role in regulating climate by absorbing nearly half of anthropogenic carbon dioxide (CO$_2$). Both physical and biogeochemical processes contribute to the net CO$_2$ sink. As a result of global warming and ozone depletion, westerly winds have increased, with consequences for upper ocean physics but little is known on how primary producers are expected to respond to changes in atmospheric forcing. This thesis addresses the impact of atmospheric forcing on upper ocean dynamics and phytoplankton bloom development in the SO on synoptic storm scales, combining a broad range of observations derived from satellites, reanalysis, profiling floats and Southern elephant seals.On atmospheric synoptic timescales (2-10 days), relevant for phytoplankton growth and accumulation, wind speed has a larger impact on satellite Chl-a variability than surface heat fluxes or wind stress curl. In summer, strong winds are linked to deep mixed layers, cold sea surface temperatures and enhanced satellite chlorophyll-a (Chl-a), which suggest wind-driven entrainment plays a role in sustaining phytoplankton blooms at the surface. Subsurface bio-optical data from floats and seals reveal deep Chl-a fluorescence maxima (DFM) are ubiquitous in summer and tend to sit at the base of the mixed layer, but can occur in all seasons. The fact that wind speed and Chl-a correlations are maximal at zero lag time (from daily data) and incubation experiments indicate phytoplankton growth occurs 3-4 days after iron addition, suggests high winds in summer entrain Chl-a from a subsurface maximum. Vertical profiles also reveal Chl-a fluorescence unevenness within hydrographically defined mixed layers, suggesting the biological timescales of adaptation through the light gradient (i.e. growth and/or photoacclimation) are often faster than mixing timescales, and periods of quiescence between storms are long enough for biological gradients to form within the homogeneous layer in density.Directional winds can also modify upwelling/subduction patterns near oceanic fronts. At the shelf-break front off Patagonia, the combined analyses of satellite and \emph{in situ} observations suggest along-front winds modulate the upwelling on synoptic timescales, potentially through a nutrient pumping mechanism associated with the interaction between along-front wind oscillations and the frontal structure through Ekman transport. Doctoral or Postdoctoral Thesis Southern Ocean University of California: eScholarship Curl ENVELOPE(-63.071,-63.071,-70.797,-70.797) Patagonia Southern Ocean |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
English |
topic |
Physical oceanography Biological oceanography Remote sensing atmospheric forcing bio-physical interactions Patagonian shelf satellite chlorophyll-a shelf-break upwelling Southern Ocean |
spellingShingle |
Physical oceanography Biological oceanography Remote sensing atmospheric forcing bio-physical interactions Patagonian shelf satellite chlorophyll-a shelf-break upwelling Southern Ocean Carranza, Magdalena On the role of atmospheric forcing on upper ocean physics in the Southern Ocean and biological impacts |
topic_facet |
Physical oceanography Biological oceanography Remote sensing atmospheric forcing bio-physical interactions Patagonian shelf satellite chlorophyll-a shelf-break upwelling Southern Ocean |
description |
The Southern Ocean (SO) plays a key role in regulating climate by absorbing nearly half of anthropogenic carbon dioxide (CO$_2$). Both physical and biogeochemical processes contribute to the net CO$_2$ sink. As a result of global warming and ozone depletion, westerly winds have increased, with consequences for upper ocean physics but little is known on how primary producers are expected to respond to changes in atmospheric forcing. This thesis addresses the impact of atmospheric forcing on upper ocean dynamics and phytoplankton bloom development in the SO on synoptic storm scales, combining a broad range of observations derived from satellites, reanalysis, profiling floats and Southern elephant seals.On atmospheric synoptic timescales (2-10 days), relevant for phytoplankton growth and accumulation, wind speed has a larger impact on satellite Chl-a variability than surface heat fluxes or wind stress curl. In summer, strong winds are linked to deep mixed layers, cold sea surface temperatures and enhanced satellite chlorophyll-a (Chl-a), which suggest wind-driven entrainment plays a role in sustaining phytoplankton blooms at the surface. Subsurface bio-optical data from floats and seals reveal deep Chl-a fluorescence maxima (DFM) are ubiquitous in summer and tend to sit at the base of the mixed layer, but can occur in all seasons. The fact that wind speed and Chl-a correlations are maximal at zero lag time (from daily data) and incubation experiments indicate phytoplankton growth occurs 3-4 days after iron addition, suggests high winds in summer entrain Chl-a from a subsurface maximum. Vertical profiles also reveal Chl-a fluorescence unevenness within hydrographically defined mixed layers, suggesting the biological timescales of adaptation through the light gradient (i.e. growth and/or photoacclimation) are often faster than mixing timescales, and periods of quiescence between storms are long enough for biological gradients to form within the homogeneous layer in density.Directional winds can also modify upwelling/subduction patterns near oceanic fronts. At the shelf-break front off Patagonia, the combined analyses of satellite and \emph{in situ} observations suggest along-front winds modulate the upwelling on synoptic timescales, potentially through a nutrient pumping mechanism associated with the interaction between along-front wind oscillations and the frontal structure through Ekman transport. |
format |
Doctoral or Postdoctoral Thesis |
author |
Carranza, Magdalena |
author_facet |
Carranza, Magdalena |
author_sort |
Carranza, Magdalena |
title |
On the role of atmospheric forcing on upper ocean physics in the Southern Ocean and biological impacts |
title_short |
On the role of atmospheric forcing on upper ocean physics in the Southern Ocean and biological impacts |
title_full |
On the role of atmospheric forcing on upper ocean physics in the Southern Ocean and biological impacts |
title_fullStr |
On the role of atmospheric forcing on upper ocean physics in the Southern Ocean and biological impacts |
title_full_unstemmed |
On the role of atmospheric forcing on upper ocean physics in the Southern Ocean and biological impacts |
title_sort |
on the role of atmospheric forcing on upper ocean physics in the southern ocean and biological impacts |
publisher |
eScholarship, University of California |
publishDate |
2016 |
url |
http://www.escholarship.org/uc/item/5qs1x85p |
op_coverage |
161 |
long_lat |
ENVELOPE(-63.071,-63.071,-70.797,-70.797) |
geographic |
Curl Patagonia Southern Ocean |
geographic_facet |
Curl Patagonia Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Carranza, Magdalena. (2016). On the role of atmospheric forcing on upper ocean physics in the Southern Ocean and biological impacts. UC San Diego: Oceanography. Retrieved from: http://www.escholarship.org/uc/item/5qs1x85p |
op_relation |
http://www.escholarship.org/uc/item/5qs1x85p qt5qs1x85p |
op_rights |
public |
_version_ |
1766206326103343104 |