Ice - ocean - atmosphere interactions in the Southern Ocean and implications for phytoplankton phenology
The annual advance and retreat of sea ice in the Southern Ocean is recognised as one of the largest seasonal events on Earth. Such considerable physical changes have profound effects on the vertical structure of the water column, and hence controls the availability of both light and nutrients to phy...
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Faculty of Science
2021
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Online Access: | http://hdl.handle.net/11427/33708 https://open.uct.ac.za/bitstream/11427/33708/1/thesis_sci_2021_hague%20mark.pdf |
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ftunivcapetownir:oai:localhost:11427/33708 2023-05-15T13:32:18+02:00 Ice - ocean - atmosphere interactions in the Southern Ocean and implications for phytoplankton phenology Hague, Mark Vichi, Marcello 2021 application/pdf http://hdl.handle.net/11427/33708 https://open.uct.ac.za/bitstream/11427/33708/1/thesis_sci_2021_hague%20mark.pdf eng eng Faculty of Science Department of Oceanography http://hdl.handle.net/11427/33708 https://open.uct.ac.za/bitstream/11427/33708/1/thesis_sci_2021_hague%20mark.pdf sea ice Southern Ocean light nutrients phytoplankton marine Doctoral Thesis Doctoral PhD 2021 ftunivcapetownir 2022-09-13T05:55:24Z The annual advance and retreat of sea ice in the Southern Ocean is recognised as one of the largest seasonal events on Earth. Such considerable physical changes have profound effects on the vertical structure of the water column, and hence controls the availability of both light and nutrients to phytoplankton. This means that in the region seasonally covered by sea ice (the SSIZ), the timing of the growth and decline (phenology) of phytoplankton is determined to a large degree by the dynamic interactions between ice, ocean and atmosphere. However, this region is simultaneously one of the most poorly observed in the global ocean, and one of the most complex. This has led to significant gaps in our understanding of how sea ice modulates the exchanges of heat and momentum between atmosphere and ocean, as well as the implications this has for phytoplankton phenology in the SSIZ. This study seeks to address these gaps by combining both model and observationallybased methods. The lack of observational data are directly tackled through an analysis of BGC-Argo float data sampling under ice. Such data reveal high growth rates in the presence of near full ice cover and deep mixed layers, conditions previously thought to prevent growth. These results suggest a revision of our current understanding of the drivers of under ice phytoplankton phenology, which should take into account the unique character of Antarctic sea ice and its effect on the under ice light environment. In addition, results obtained from several numerical process studies indicates that phytoplankton may have a higher affinity for low light conditions than previously thought. From a modelling perspective, an analysis and intercomparison of 11 Earth System Models (ESMs) and their representation of vertical mixing and phenology is presented. This revealed that misrepresentations in phenology where driven by model biases in sea ice cover and vertical mixing. That is, only models with either too much or too little ice cover were able to simulate phenology ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Sea ice Southern Ocean University of Cape Town: OpenUCT Antarctic Southern Ocean |
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University of Cape Town: OpenUCT |
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ftunivcapetownir |
language |
English |
topic |
sea ice Southern Ocean light nutrients phytoplankton marine |
spellingShingle |
sea ice Southern Ocean light nutrients phytoplankton marine Hague, Mark Ice - ocean - atmosphere interactions in the Southern Ocean and implications for phytoplankton phenology |
topic_facet |
sea ice Southern Ocean light nutrients phytoplankton marine |
description |
The annual advance and retreat of sea ice in the Southern Ocean is recognised as one of the largest seasonal events on Earth. Such considerable physical changes have profound effects on the vertical structure of the water column, and hence controls the availability of both light and nutrients to phytoplankton. This means that in the region seasonally covered by sea ice (the SSIZ), the timing of the growth and decline (phenology) of phytoplankton is determined to a large degree by the dynamic interactions between ice, ocean and atmosphere. However, this region is simultaneously one of the most poorly observed in the global ocean, and one of the most complex. This has led to significant gaps in our understanding of how sea ice modulates the exchanges of heat and momentum between atmosphere and ocean, as well as the implications this has for phytoplankton phenology in the SSIZ. This study seeks to address these gaps by combining both model and observationallybased methods. The lack of observational data are directly tackled through an analysis of BGC-Argo float data sampling under ice. Such data reveal high growth rates in the presence of near full ice cover and deep mixed layers, conditions previously thought to prevent growth. These results suggest a revision of our current understanding of the drivers of under ice phytoplankton phenology, which should take into account the unique character of Antarctic sea ice and its effect on the under ice light environment. In addition, results obtained from several numerical process studies indicates that phytoplankton may have a higher affinity for low light conditions than previously thought. From a modelling perspective, an analysis and intercomparison of 11 Earth System Models (ESMs) and their representation of vertical mixing and phenology is presented. This revealed that misrepresentations in phenology where driven by model biases in sea ice cover and vertical mixing. That is, only models with either too much or too little ice cover were able to simulate phenology ... |
author2 |
Vichi, Marcello |
format |
Doctoral or Postdoctoral Thesis |
author |
Hague, Mark |
author_facet |
Hague, Mark |
author_sort |
Hague, Mark |
title |
Ice - ocean - atmosphere interactions in the Southern Ocean and implications for phytoplankton phenology |
title_short |
Ice - ocean - atmosphere interactions in the Southern Ocean and implications for phytoplankton phenology |
title_full |
Ice - ocean - atmosphere interactions in the Southern Ocean and implications for phytoplankton phenology |
title_fullStr |
Ice - ocean - atmosphere interactions in the Southern Ocean and implications for phytoplankton phenology |
title_full_unstemmed |
Ice - ocean - atmosphere interactions in the Southern Ocean and implications for phytoplankton phenology |
title_sort |
ice - ocean - atmosphere interactions in the southern ocean and implications for phytoplankton phenology |
publisher |
Faculty of Science |
publishDate |
2021 |
url |
http://hdl.handle.net/11427/33708 https://open.uct.ac.za/bitstream/11427/33708/1/thesis_sci_2021_hague%20mark.pdf |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic Sea ice Southern Ocean |
genre_facet |
Antarc* Antarctic Sea ice Southern Ocean |
op_relation |
http://hdl.handle.net/11427/33708 https://open.uct.ac.za/bitstream/11427/33708/1/thesis_sci_2021_hague%20mark.pdf |
_version_ |
1766025689421578240 |