- Title
- Investigating the interannual variability of the Benguela coastal upwelling system using a ROMS numerical model from 1993-2014
- Creator
- Silima, Rudzani Faith
- Creator
- Roagosha, Moagabo
- Subject
- Oceanography
- Subject
- Coasts
- Subject
- Marine sciences
- Date Issued
- 2023-12
- Date
- 2023-12
- Type
- Master's theses
- Type
- text
- Identifier
- http://hdl.handle.net/10948/62586
- Identifier
- vital:72826
- Description
- The seasonal and interannual variability of the coastal Benguela upwelling system is described using 22 years (September 1993 - December 2014) of a regional Ocean model (ROMS) output. The model-derived SSTs are evaluated against satellite SSTs (GHRSST) and biases between the datasets investigated, allowing for confidence in using the ROMS data to investigate details of spatial and temporal variability over the Benguela System. Variability of coastal SSTs are investigated together with alongshore winds (from the ERA-Interim Reanalysis product). The driver of the seasonality in upwelling in the Benguela region is the seasonal shift of the South Atlantic High pressure system, leading to an enhanced seasonal signal in the southern Benguela (with strongest upwelling favourable winds in austral spring and summer). In the northern Benguela, the seasonal signal reduces with the peak of upwelling favourable winds shifting to late winter and spring. Interannual variability is evident in the model and is investigated with respect to various modes of climate variability. Though the direct relationship of the Benguela upwelling system to large-scale climate modes such as SAM and ENSO is not clear in most places, some evidence was found for their connection. For instance, in the southernmost cell of the southern Benguela a significant positive and negative correlation exists between SST and wind respectively with ENSO during summer months. This relates to increased (decreased) winds and decreased (increased) SST during La Niña (El Niño) events. Although there was no direct correlation with either SST or alongshore wind anywhere in the Benguela system, there was some indication of its importance. A trend toward a positive SAM (i.e a more poleward position of the South Atlantic High-Pressure system) was consistent with a trend toward enhanced winds and reduced SSTs in the southernmost upwelling cell. In addition to this, there was evidence to suggest that when SAM and ENSO are out-of-phase, which occurred primarily during summer months, the wind and SST response is amplified. This seemed to be particularly true in the first 10 years of the timeseries when the anomalies were strongly alternating.
- Description
- Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
- Format
- computer
- Format
- online resource
- Format
- application/pdf
- Format
- 1 online resource (69 pages)
- Format
- Publisher
- Nelson Mandela University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela University
- Rights
- All Rights Reserved
- Rights
- Open Access
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NMU School of Environmental Sciences
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | Silima, RF.pdf | 8 MB | Adobe Acrobat PDF | View Details Download |