Abstract
Seasonal coastal upwelling was analyzed along the NW African coastline (11–35°N) from 1981 to 2012. Upwelling magnitudes are calculated by wind speed indices, sea-surface temperature indices and inferred from meteorological station, sea-surface height and vertical water column transport data. A permanent annual upwelling regime is documented across 21–35°N and a seasonal regime across 12–19°N, in accordance with the climatology of previous studies. Upwelling regions were split into three zones: (1) the Mauritania–Senegalese upwelling zone (12–19°N), (2) the strong permanent annual upwelling zone (21–26°N) and (3) the weak permanent upwelling zone (26–35°N). We find compelling evidence in our various indices for the Bakun upwelling intensification hypothesis due to a significant coastal summer wind speed increase, resulting in an increase in upwelling-favorable wind speeds north of 20°N and an increase in downwelling-favorable winds south of 20°N. The North Atlantic Oscillation plays a leading role in modifying interannual variability during the other seasons (autumn–spring), with its influence dominating in winter. The East Atlantic pattern shows a strong correlation with upwelling during spring, while El Niño Southern Oscillation and Atlantic Multi-decadal Oscillation teleconnections were not found. A disagreement between observationally-based wind speed products and reanalysis-derived data is explored. A modification to the Bakun upwelling intensification hypothesis for NW Africa is presented, which accounts for the latitudinal divide in summer wind regimes.
Highlights
The Canary Upwelling Ecosystem (CUE) situated off Northwest (NW) Africa (11–351N, Fig. 1) is an important socio-economic, oceanographic and climatological region
Upwelling appears to be a permanent annual phenomenon up to $ 331N – a small zone around $ 301N near Cape Ghir appears to have much weaker upwelling compared to the surrounding latitudes
Upwelling occurs during the winter months and fades during the summer months, related to the seasonal migration of the trade winds; 2. 21–261N – Strong permanent annual upwelling zone; 3. 26–351N – Weak permanent annual upwelling zone
Summary
The Canary Upwelling Ecosystem (CUE) situated off Northwest (NW) Africa (11–351N, Fig. 1) is an important socio-economic, oceanographic and climatological region. The Canary Current itself is the eastern, southward flowing component of the North Atlantic Subtropical Gyre and is one of the major coastal upwelling regions of the world, along with the Benguela (Hagen et al, 2001), Humboldt (Thiel et al, 2007) and California (Pérez-Brunius et al, 2007) eastern boundary upwelling ecosystems (EBUE) These EBUEs cover approximately 1% of the total ocean surface but account for over 20% of the global fish catch (Pauly and Christensen, 1995); monitoring changes across these regions is of the upmost importance, especially as a fisheries response to global climate change has recently been documented (Cheung et al, 2013; Payne, 2013). Upwelled water is typically denser, cooler and richer in nutrients than surface waters and has significant impacts on coastal climates and marine biology (Miranda et al, 2012)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Deep Sea Research Part I: Oceanographic Research Papers
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
