References of "Mason, Evan"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailImpact of vertical and horizontal advection on nutrient distribution in the southeast Pacific
Barceló-Llull, Barbara; Mason, Evan; Capet, Arthur ULg et al

in Ocean Science (2016), 12(4), 1003-1011

An innovative approach is used to analyze the impact of vertical velocities associated with quasi-geostrophic (QG) dynamics on the redistribution and uptake of nitrate in the southeast Pacific (SEP). A ... [more ▼]

An innovative approach is used to analyze the impact of vertical velocities associated with quasi-geostrophic (QG) dynamics on the redistribution and uptake of nitrate in the southeast Pacific (SEP). A total of 12 years of vertical and horizontal currents are derived from an observation based estimate of the ocean state. Horizontal velocities are obtained through the application of thermal wind balance to weekly temperature and salinity fields. Vertical velocities are estimated by integration of the QG omega equation. Seasonal variability of the synthetic vertical velocity and kinetic energy associated with the horizontal currents is coincident, with peaks in austral summer (November–December) in accord with published observations. The impact of vertical velocity on SEP nitrate uptake rates is assessed by using two Lagrangian particle tracking experiments that differ according to vertical forcing (ω = ωQG vs. ω = 0). From identical initial distributions of nitrate-tagged particles, the Lagrangian results show that vertical motions induce local increases in nitrate uptake reaching up to 30 %. Such increases occur in low uptake regions with high mesoscale activity. Despite being weaker than horizontal currents by a factor of up to 10−4, vertical velocity associated with mesoscale activity is demonstrated to make an important contribution to nitrate uptake, hence productivity, in low uptake regions. [less ▲]

Detailed reference viewed: 21 (1 ULg)
Full Text
Peer Reviewed
See detailImplications of Refined Altimetry on Estimates of Mesoscale Activity and Eddy-Driven Offshore Transport in the Eastern Boundary Upwelling Systems
Capet, Arthur ULg; Mason, Evan; Rossi, Vincent et al

in Geophysical Research Letters (2014), 41

We investigate the extent to which the recently upgraded version of the Ssalto/Duacs sea level anomaly product affects the description of mesoscale activity in the Eastern Boundary Upwelling Systems (EBUS ... [more ▼]

We investigate the extent to which the recently upgraded version of the Ssalto/Duacs sea level anomaly product affects the description of mesoscale activity in the Eastern Boundary Upwelling Systems (EBUS). Drifter observations confirm that the new data set released by Archiving, Validation and Interpretation of Satellite Oceanographic data (AVISO) in April 2014 (DT14) offers an enhanced description of mesoscale activity for the four EBUS. DT14 returns significantly higher eddy kinetic energy levels (+80%) within a 300 km coastal band, where mesoscale structures are known to induce important lateral physical and biogeochemical fluxes. When applied to DT14, an automatic eddy detection algorithm detects more eddies in the EBUS (+37%), and lower eddy radius estimates, in comparison with results using the former altimetry product (DT10). We show that despite higher eddy densities, the smaller eddy radii result in westward eddy transport estimates that are smaller than those obtained from DT10 ( −12%). [less ▲]

Detailed reference viewed: 1 (0 ULg)
Full Text
Peer Reviewed
See detailGeneration of the Cape Ghir upwelling filament: A numerical study
Troupin, Charles ULg; Mason, Evan; Beckers, Jean-Marie ULg et al

in Ocean Modelling (2012), 41

Filaments are narrow, shallow structures of cool water originating from the coast. They are typical features of the four main eastern boundary upwelling systems (EBUS). In spite of their significant ... [more ▼]

Filaments are narrow, shallow structures of cool water originating from the coast. They are typical features of the four main eastern boundary upwelling systems (EBUS). In spite of their significant biological and chemical roles, through the offshore exportation of nutrient-rich waters, the physical processes that generate them are still not completely understood. This paper is a process-oriented study of filament generation mechanisms. Our goal is twofold: firstly, to obtain a numerical solution able to well represent the characteristics of the filament off Cape Ghir (30°38'N, northwestern Africa) in the Canary EBUS and secondly, to explain its formation by a simple mechanism based on the balance of potential vorticity. The first goal is achieved by the use of the ROMS model (Regional Ocean Modeling System) in embedded domains around Cape Ghir, with a horizontal resolution going up to 1.5 km for the finest domain. The latter gets its initial and boundary conditions from a parent solution and is forced by climatological, high-resolution atmospheric fields. The modeled filaments display spatial, temporal and physical characteristics in agreement with the available in situ and satellite observations. This model solution is used as a reference to compare the results with a set of process-oriented experiments. These experiments allow us to reach the second objective. Their respective solution serves to highlight the contribution of various processes in the filament generation. Since the study is focused on general processes present under climatological forcing conditions, inter-annual forcing is not necessary. The underlying idea for the filament generation is the balance of potential vorticity in the Canary EBUS: the upwelling jet is characterized by negative relative vorticity and flows southward along a narrow band of uniform potential vorticity. In the vicinity of the cape, an injection of relative vorticity induced by the wind breaks the existing vorticity balance. The upwelling jet is prevented from continuing its way southward and has to turn offshore to follow lines of equal potential vorticity. The model results highlight the essential role of wind, associated with the particular topography (coastline and bottom) around the cape. The mechanism presented here is general and thus can be applied to other EBUS. [less ▲]

Detailed reference viewed: 110 (10 ULg)
Full Text
Peer Reviewed
See detailSeasonal variability of the Canary Current: a numerical study
Mason, Evan; Colas, François; Molemaker, Jeroen et al

in Journal of Geophysical Research. Oceans (2011), 116

Detailed reference viewed: 46 (0 ULg)
Full Text
See detailA new mechanism of upwelling generated filaments based on potential vorticity balance
Troupin, Charles ULg; Mason, Evan; Beckers, Jean-Marie ULg et al

Conference (2009, April 27)

Detailed reference viewed: 12 (0 ULg)
Full Text
Peer Reviewed
See detailA new mechanism of upwelling generated filaments based on potential vorticity balance
Troupin, Charles ULg; Mason, Evan; Beckers, Jean-Marie ULg et al

Poster (2009, April 19)

Detailed reference viewed: 13 (1 ULg)
Full Text
See detailVorticity balance in the Northwestern African Upwelling
Troupin, Charles ULg; Mason, Evan; Sangrà, Pablo

Poster (2008, October 06)

Detailed reference viewed: 11 (0 ULg)
Full Text
Peer Reviewed
See detailVorticity balance in the Northwestern African Upwelling
Troupin, Charles ULg; Mason, Evan; Sangrà, Pablo

Conference (2008, June 02)

Detailed reference viewed: 20 (0 ULg)