SST patterns and dynamics of the southern Senegal‐Gambia upwelling center

Abstract

The southern end of the Canary current system comprises of an original upwelling center that has so far received little attention, the Southern Senegal-Gambia Upwelling Center (SSUC). We investigate its dynamical functioning by taking advantage of favorable conditions in terms of limited cloud coverage. Analyses and careful examinations of over 1500 satellite images of sea surface temperature scenes contextualized with respect to wind conditions confirm the regularity and stability of the SSUC dynamical functioning (as manifested by the recurrence and persistence of particular SST patterns). The analyses also reveal subtle aspects of its upwelling structure: shelf break cooling of surface waters consistent with internal tide breaking/mixing; complex interplay between local upwelling and the Mauritanian current off the Cape Verde headland; complexity of the inner-shelf/mid shelf frontal transition. The amplitude of the diurnal cycle suggests that large uncertainties exist in the SSUC heat budget. The studies limitations underscore the need for continuous in situ measurement in the SSUC, particularly of winds.

A model study of the seasonality of sea surface temperature and circulation in the Atlantic North-eastern Tropical Upwelling System

“…Next section, we describe the CP and WP general circulation and SST change patterns in the observation-derived products, and validate the simulation. [36]. The model presents a more noisy structure ( Figure 3B), due to the shorter length of average period relative to the observations.…”

Contrasted optimal environmental windows for both sardinella species in Senegalese waters

“…These observed differences might be due to their physiological characteristics which are relatively distinct: S. aurita is more sensitive to temperature and salinity fluctuation than S. maderensis , which tolerate higher change in salinity and temperature (Ba et al., ; Cury & Fontana, ). This is also explained by the fact that, even if both species occupy the same area in Senegal (Cury & Fontana, ), their relative abundance strongly differs between Northern Senegal (in connection with Mauritania) and Southern Senegal (Capet et al., ; Ndoye et al., ), warmer and less sensitive to the detrimental effects of a strong upwelling season.…”

“…This upwelling system begins in late autumn and ends in spring (Teisson, ). In the region north of Dakar, where the continental shelf is narrow, the upwelling occurs near the coast, while south of Dakar characterized by a larger continental shelf and the upwelling is a trapped cold water tongue in the middle of the continental shelf surrounded by warmed waters (Ndoye et al., ). The Senegalese upwelling is marked by great seasonal and interannual variability thought to have effects on small pelagic fish (Bakun, ; Cury & Roy, ; Fréon, ; Fréon & Mendoza, ).…”

Dynamics of a “low‐enrichment high‐retention” upwelling center over the southern Senegal shelf

“…Examples of instantaneous SST (°C) fields from (a) S hfw and (b) L2 MODIS for the core of the SSUS upwelling period (February–April). February–April climatological probability density function for the distribution of zonal SST minima computed in 2 km latitude bands (longitude binning also uses a 2 km mesh size) for (c) S hfw and (d) L2 MODIS (see details in Ndoye et al []); note the nonlinear color scales for these two panels. February–April mean climatological sea level from (e) S hfw and (f) observations combining the 2013 CNES‐CLS mean dynamic topography with DUACS monthly sea level anomalies.…”