Weijer Wilbert

No Thumbnail Available
Last Name
Weijer
First Name
Wilbert
ORCID

Filters

2015 - 2018 4
4
4
Reset filters

Settings

Search Results

Now showing 1 - 4 of 4
  • Article
    Author Correction : Spiraling pathways of global deep waters to the surface of the Southern Ocean
    (Nature Publishing Group, 2018-01-15) Tamsitt, Veronica ; Drake, Henri F. ; Morrison, Adele K. ; Talley, Lynne D. ; Dufour, Carolina O. ; Gray, Alison R. ; Griffies, Stephen M. ; Mazloff, Matthew R. ; Sarmiento, Jorge L. ; Wang, Jinbo ; Weijer, Wilbert
    Correction to: Nature Communications 8:172 https://doi.org/10.1038/s41467-017-00197-0; Article published online: 2 August 2017
  • Article
    Lagrangian timescales of Southern Ocean upwelling in a hierarchy of model resolutions
    (John Wiley & Sons, 2018-01-31) Drake, Henri F. ; Morrison, Adele K. ; Griffies, Stephen M. ; Sarmiento, Jorge L. ; Weijer, Wilbert ; Gray, Alison R.
    In this paper we study upwelling pathways and timescales of Circumpolar Deep Water (CDW) in a hierarchy of models using a Lagrangian particle tracking method. Lagrangian timescales of CDW upwelling decrease from 87 years to 31 years to 17 years as the ocean resolution is refined from 1° to 0.25° to 0.1°. We attribute some of the differences in timescale to the strength of the eddy fields, as demonstrated by temporally degrading high-resolution model velocity fields. Consistent with the timescale dependence, we find that an average Lagrangian particle completes 3.2 circumpolar loops in the 1° model in comparison to 0.9 loops in the 0.1° model. These differences suggest that advective timescales and thus interbasin merging of upwelling CDW may be overestimated by coarse-resolution models, potentially affecting the skill of centennial scale climate change projections.
  • Article
    Spiraling pathways of global deep waters to the surface of the Southern Ocean
    (Nature Publishing Group, 2017-08-02) Tamsitt, Veronica ; Drake, Henri F. ; Morrison, Adele K. ; Talley, Lynne D. ; Dufour, Carolina O. ; Gray, Alison R. ; Griffies, Stephen M. ; Mazloff, Matthew R. ; Sarmiento, Jorge L. ; Wang, Jinbo ; Weijer, Wilbert
    Upwelling of global deep waters to the sea surface in the Southern Ocean closes the global overturning circulation and is fundamentally important for oceanic uptake of carbon and heat, nutrient resupply for sustaining oceanic biological production, and the melt rate of ice shelves. However, the exact pathways and role of topography in Southern Ocean upwelling remain largely unknown. Here we show detailed upwelling pathways in three dimensions, using hydrographic observations and particle tracking in high-resolution models. The analysis reveals that the northern-sourced deep waters enter the Antarctic Circumpolar Current via southward flow along the boundaries of the three ocean basins, before spiraling southeastward and upward through the Antarctic Circumpolar Current. Upwelling is greatly enhanced at five major topographic features, associated with vigorous mesoscale eddy activity. Deep water reaches the upper ocean predominantly south of the Antarctic Circumpolar Current, with a spatially nonuniform distribution. The timescale for half of the deep water to upwell from 30° S to the mixed layer is ~60–90 years.
  • Article
    Eddy-driven sediment transport in the Argentine Basin : is the height of the Zapiola Rise hydrodynamically controlled?
    (John Wiley & Sons, 2015-03-27) Weijer, Wilbert ; Maltrud, Mathew E. ; Homoky, William B. ; Polzin, Kurt L. ; Maas, Leo R. M.
    In this study, we address the question whether eddy-driven transports in the Argentine Basin can be held responsible for enhanced sediment accumulation over the Zapiola Rise, hence accounting for the existence and growth of this sediment drift. To address this question, we perform a 6 year simulation with a strongly eddying ocean model. We release two passive tracers, with settling velocities that are consistent with silt and clay size particles. Our experiments show contrasting behavior between the silt fraction and the lighter clay. Due to its larger settling velocity, the silt fraction reaches a quasisteady state within a few years, with abyssal sedimentation rates that match net input. In contrast, clay settles only slowly, and its distribution is heavily stratified, being transported mainly along isopycnals. Yet, both size classes display a significant and persistent concentration minimum over the Zapiola Rise. We show that the Zapiola Anticyclone, a strong eddy-driven vortex that circulates around the Zapiola Rise, is a barrier to sediment transport, and hence prevents significant accumulation of sediments on the Rise. We conclude that sediment transport by the turbulent circulation in the Argentine Basin alone cannot account for the preferred sediment accumulation over the Rise. We speculate that resuspension is a critical process in the formation and maintenance of the Zapiola Rise.