A comparison of the structure and variability of the flow field in three coastal upwelling regions: Oregon, northwest Africa, and Peru

1981 ◽  
pp. 107-118 ◽  
Author(s):  
Robert L. Smith
Keyword(s):  
Flow Field ◽  
Coastal Upwelling ◽  
Northwest Africa

scholarly journals Environmental control on the variability of DMS and DMSP in the Mauritanian upwelling region

2012 ◽  
Vol 9 (3) ◽  
pp. 1041-1051 ◽  
Author(s):  
C. Zindler ◽  
I. Peeken ◽  
C. A. Marandino ◽  
H. W. Bange
Keyword(s):  
Surface Waters ◽  
Coastal Upwelling ◽  
Environmental Control ◽  
Hot Spot ◽  
Local Source ◽  
Surface Seawater ◽  
Near Surface ◽  
Northwest Africa ◽  
N:P Ratios ◽  
A Minor

Abstract. Dimethylsulphide (DMS) and dissolved and particulate dimethylsulfoniopropionate (DMSPd, DMSPp) were measured in near-surface waters along the Mauritanian coast, Northwest Africa, during the upwelling season in February 2008. DMS, DMSPd and DMSPp surface concentrations of up to 10 nmol L−1, 15 nmol L−1 and 990 nmol L−1, respectively, were measured. However, the DMS concentrations measured are in the low range compared to other upwelling regions. The maximum DMSPp concentration is the highest reported from upwelling regions so far, which might indicate that the Mauritanian upwelling is a hot spot for DMSP. Within the phytoplankton groups, dinoflagellates were identified as important contributors to DMS concentrations, while other algae seemed to have only a minor or no influence on DMS and DMSP concentrations. A pronounced switch from high DMSP to high DMS concentrations was observed when the nitrogen to phosphorus ratio (N:P) was below 7. The high DMS/DMSP ratios at N:P ratios <7 indicate that nitrogen limitation presumably triggered a switch from DMSP to DMS independent of the species composition. Our results underline the importance of coastal upwelling regions as a local source for surface seawater sulphur.

scholarly journals Environmental control on the variability of DMS and DMSP in the Mauritanian upwelling region

2011 ◽  
Vol 8 (4) ◽  
pp. 8591-8618
Author(s):  
C. Zindler ◽  
I. Peeken ◽  
C. A. Marandino ◽  
H. W. Bange
Keyword(s):  
Nitrogen Limitation ◽  
Coastal Upwelling ◽  
Environmental Control ◽  
Hot Spot ◽  
Northwest Africa ◽  
Induced Stress ◽  
Temporal And Spatial Variability ◽  
Temporal And Spatial ◽  
A Minor ◽  
The Tropics

Abstract. Dimethylsulfide (DMS) and dissolved and particulate dimethylsulfoniopropionate (DMSPd, DMSPp) were measured in sea surface layer along the Mauritanian coast, Northwest Africa, during the upwelling season in February 2008. DMS, DMSPd and DMSPp surface concentrations of up to 10 nmol L−1, 15 nmol L−1 and 990 nmol L−1, respectively, were measured. The maximum DMSPp concentration is the highest reported from upwelling regions so far and indicates that the Mauritanian upwelling is a hot spot of DMSP and, thus, DMS production. Dinoflagellates were responsible for the DMS production. Other phytoplankton groups seemed to have only a minor or no influence on the DMS and DMSP production. Decreasing nitrogen (i.e. increasing nitrogen limitation) most likely triggered a switch from high DMSP production to high DMS production. It seems that both nitrogen limitation and the intensive solar radiation in the tropics induced stress in DMSP producing algae and activated their antioxidant system. Our results underline the importance of coastal upwelling regions as ecosystems with a pronounced temporal and spatial variability which result in high DMSP and DMS production.

Representation of Northwest African upwelling in CMIP5 models

2020 ◽  
Author(s):  
Antonio Castaño-Tierno ◽  
Belén Rodríguez-Fonseca ◽  
Elsa Mohino ◽  
Teresa Losada
Keyword(s):  
Coastal Upwelling ◽  
Sea Surface ◽  
Cmip5 Models ◽  
Pressure Gradients ◽  
Ekman Pumping ◽  
North West ◽  
The North ◽  
Northwest Africa ◽  
Leading Mode ◽  
Pressure Changes

&lt;p&gt;The Northwest Africa (NWA) upwelling region is located along the Senegalese and Mauritanian coast, between 10&amp;#176;N and 25&amp;#176;N and in a very narrow longitudinal band. In this region, most of the upwelled waters are due to alongshore surface winds through Ekman pumping.&lt;/p&gt;&lt;p&gt;The rapid increase in the upper ocean upwelling in this region along the 20th century and the contradictions found about future projections put forward the need for a better understanding of model&amp;#8217;s ability to simulate Ekman induced upwelling processes.&lt;/p&gt;&lt;p&gt;In this work we assess intermodel variability to better understand the causes of different responses and spread among a set of CMIIP5 models. &amp;#160;&lt;/p&gt;&lt;p&gt;Results suggest that the seasonal cycle of NWA upwelling is qualitatively well simulated by CMIP5 models, although models tend to show strong biases for the permanent upwelling latitudes (north of 20&amp;#176;N) and the seasonal upwelling area (around 15&amp;#176;N in boreal spring). The maximum vertical temperature gradient shown by CMIP5 models is higher than that of SODA reanalysis and prevents cold waters from deeper layers to reach the surface, thus making coastal upwelling less effective in affecting sea surface temperatures.&lt;/p&gt;&lt;p&gt;Most of the intermodel variance is explained by the two first EOF modes of intermodel variability. The first mode shows a latitudinal structure, with a maximum in the permanent upwelling season, while. the second one is more seasonal. Both modes are very related to changes in the North-West Africa land-sea surface pressure gradient. In the case of the leading mode, incoming solar radiation differences between the North African desert and the ocean are the cause of the pressure gradients. For the second mode pressure changes in the Atlantic Ocean are driven by ITCZ shifts in response to interhemispheric differential warming.&lt;/p&gt;

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