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Browsing by Author "Vichi, Marcello"

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A novel approach to investigating chlorophyll-a fluorescence quantum yield variability in the Southern Ocean

Author: Bone, Emma Lewis Date: 2019 The apparent fluorescence quantum yield of chlorophyll-a (ΦF ), i.e. the ratio of photons emitted as chlorophyll-a fluorescence to those absorbed by phytoplankton, serves as a first order measure of photosynthetic efficiency and a photophysiological ... Read more
A preliminary investigation on the relationships between upwelling and commercial hake fishery in the Southern Benguela

Author: Memela, Nkuleleko Date: 2021 The hake bottom trawl division is the largest component of the fishing industry in South Africa and it is one of the strong pillars of the food industry and the national economy. It is the main source of livelihood for many people in the West ... Read more
Assessment of early 20th Century climate model simulations of Antarctic Sea ice using historical commercial humpback whale catch data

Author: Mazomba, Thando Date: 2021 The story of Southern Hemisphere humpback whales through time presents multiple narratives. This study integrated two of those narratives to better understand our climate over time - the ecological behaviour of this species as well as their ... Read more
Assessment of the synoptic variability of the Antarctic marginal ice zone with in Situ observations

Author: de Jong, Ehlke Date: 2019 Knowledge of sea ice variability, which contributes to the detection of climate change trends, stems primarily from remote sensing information. However, sea ice in the Southern Ocean is characterised by large variability that remains unresolved ... Read more
Atmospheric drivers of ice drift in the Antarctic marginal ice zone

Author: Womack, Ashleigh Catherine Stevenson Date: 2021 Sea-ice drift in the Antarctic marginal ice zone (MIZ) was investigated using an array of five drifting ice buoys, deployed during the winter sea-ice expansion, in July 2017. An initial 15- day analysis of pancake ice drift is presented, using ... Read more
Characterising the response of the mixed and the transitional layers to the passage of storms in the Sub-Antarctic Zone

Author: Mpalweni, Ayanda Date: 2019 Mid-latitude storms are common in the Southern Ocean (SO) and have been shown to drive substantial vertical mixing, leaving behind wakes of perturbed upper ocean. The vertical extent and duration of the impact of these storms on the upper ... Read more
A Computational Fluid Dynamics Model for the Small-Scale Dynamics of Wave, Ice Floe and Interstitial Grease Ice Interaction

Author: Marquart, Rutger ; Bogaers, Alfred ; Skatulla, Sebastian ; Alberello, Alberto ; Toffoli, Alessandro ; Schwarz, Carina ; Vichi, Marcello Date: 29 Apr 2021 The marginal ice zone is a highly dynamical region where sea ice and ocean waves interact. Large-scale sea ice models only compute domain-averaged responses. As the majority of the marginal ice zone consists of mobile ice floes surrounded by ... Read more c b
Estimates of Phytoplankton carbon from high resolution optical sensors in the Southern Ocean

Author: Ogunkoya, Ayodele Gilbert Date: 2015 Phytoplankton is an important component of the oceanic carbon cycle, and deriving a good estimate of its carbon biomass (Cphyto) at ocean scale is difficult due to the lack of automatic sampling procedures. This is particularly difficult in ... Read more
Exploring South Africa’s southern frontier: A 20-year vision for polar research through the South African National Antarctic Programme

Author: Ansorge, Isabelle J ; Skelton, Paul ; Bekker, Annie ; de Bruyn, P J Nico ; Butterworth, Doug S ; Cilliers, Pierre ; Cooper, John ; Cowan, Don A ; Dorrington, Rosemary ; Fawcett, Sarah ; Fietz, Susanne ; Findlay, Ken P ; Froneman, P William ; Grantham, Geoff H ; Greve, Michelle ; Hedding, David ; Hofmeyr, G J Greg ; Kosch, Michael ; le Roux, Peter ; Lucas, Mike ; MacHutcho, Keith ; Meiklejohn, Ian ; Nel, Werner ; Pistorius, Pierre ; Ryan, Peter ; Stander, Johan ; Swart, Sebastiaan ; Treasure, Anne ; Vichi, Marcello ; Jansen van Vuuren, Bettine Date: Jun 2017 Antarctica, the sub-Antarctic islands and surrounding Southern Ocean are regarded as one of the planet’s last remaining wildernesses, ‘insulated from threat by [their] remoteness and protection under the Antarctic Treaty System’1 . Antarctica ... Read more c b
Frazil Ice in the Antarctic Marginal Ice Zone

Author: Paul, Felix ; Mielke, Tommy ; Schwarz, Carina ; Schröder, Jörg ; Rampai, Tokoloho ; Skatulla, Sebastian ; Audh, Riesna R ; Hepworth, Ehlke ; Vichi, Marcello ; Lupascu, Doru C Date: 10 Jun 2021 Frazil ice, consisting of loose disc-shaped ice crystals, is the first ice that forms in the annual cycle in the marginal ice zone (MIZ) of the Antarctic. A sufficient number of frazil ice crystals form the surface “grease ice” layer, playing ... Read more c b
Hydrographic conditions of a continental shelf region in the Northwest African Upwelling System from in-situ data

Author: Juby, Paul Robert Date: 2015 This study investigates the hydrographic and dynamic properties of the continental shelf region between Cape Juby (28.5 °N) and Agadir (30.4 °N) within the Moroccan Sub-region of the North West African Upwelling System. Data came from two ... Read more
Ice - ocean - atmosphere interactions in the Southern Ocean and implications for phytoplankton phenology

Author: Hague, Mark Date: 2021 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 ... Read more
Improved estimates and understanding of interannual trends of CO₂ fluxes in the Southern Ocean

Author: Gregor, Luke Date: 2017 The Southern Ocean plays an important role in mitigating the effects of anthropogenically driven climate change. The region accounts for 43% of oceanic uptake of anthropogenic carbon dioxide (CO₂). This is foreseen to change with increasing ... Read more
Intra-seasonal variability of Southern Ocean primary production: the role of storms and mesoscale turbulence

Author: Nicholson, Sarah-Anne Date: 2016 The Southern Ocean is one of the stormiest places on earth; here strong mid-latitude storms frequently traverse large distances of this ocean. Underlying these passing storms, the Southern Ocean is characterized by having some of the highest ... Read more
Investigating the relationship between volume transport and sea surface height in the Agulhas Current System

Author: Vermeulen, Estee Date: 2018 The relationship between the volume transport of the Agulhas Current at 34°S (the position of the Agulhas Current Time-series array) and the gradient of sea surface height across the current was investigated using a regional Hybrid Coordinate ... Read more
Investigating the sensitivity of one-dimensional turbulence schemes in the sub-Antarctic Southern Ocean

Author: Boodhraj, Kirodh Date: 2018 The sub-Antarctic Zone (SAZ) is a zone of vigorous vertical mixing in the Southern Ocean where it is difficult to obtain data for model validation on the turbulence conditions. In this study, a onedimensional configuration from the Nucleus ... Read more
Investigation of Wind Variability in the South Atlantic Sector of the Southern Ocean and the Influence on the Upper Ocean in a Numerical Ocean Model

Author: Moalusi, Tumelo Comfort Date: 2019 Several papers have linked climate variability in the Southern Ocean (SO) with the Southern Annular Mode (SAM), which has seen an increase in the positive phase since the mid-1960s, due to the Antarctic ozone depletion and emissions of ... Read more
Modelling waves and near-shore circulation around the Cape Peninsula: towards enhanced predictions for South African coastal activities

Author: de Vos, Marc Date: 2022 South Africa's coastal oceans support a multitude of human and ecological interests. My work at the confluence of academia, industry and government highlighted a gap in knowledge and capacity in the marine environmental information space. ... Read more
Not all models are created equal: assessing parameterisations of iron dynamics in ocean biogeochemical models

Author: Rogerson, Jonathan J Date: 2020 Iron is one of the most commonly studied trace metals as it exerts a significant influence on ocean productivity, carbon sequestration as well as modulating atmospheric CO2 concentrations. As iron is such a vital nutrient for biogeochemical ... Read more
Quantifying spatial and temporal scales of phytoplankton variability in the Sub-Antarctic Ocean using a high-resolution glider dataset

Author: Little, Hazel Jean Date: 2016 Phytoplankton in the Sub-Antarctic Southern Ocean have a distinct seasonal cycle, which is highly variable in both space and time. The seasonal and spatial distribution of chlorophyll can be attributed to the complex nature of the physical ... Read more

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