Estimation of vertical velocities associated with large scale dynamics in the Atlantic ocean.

Alban Lazar (LOCEAN-IPSL, Sorbonne Université, France)


Magnim Gnamah (LOCEAN-IPSL, Sorbonne Université, France); Siny Ndoye (LPAOSF-ESP-UCAD, Senegal)

Event: 2018 Ocean Surface Topography Science Team Meeting

Session: Others (poster only)

Presentation type: Type Poster

Vertical velocities in the ocean are generally too weak to be measured, especially at monthly to longer time-scales. In particular, that is the case of the vertical movements associated to the large-scale relatively slow dynamics. This prevents any accurate assessment of the thermohaline circulation and ventilation (mass, heat, oxygen and other tracer fluxes). In this work, we compute the three-dimensional time-mean vertical velocities w of an Atlantic basin simulation, using the density field and the linear vorticity balance (LVB), and compare it to the model w. The validity of the LVB and the errors of the estimated velocities are quantified using the simulation as the reference.
We show that large regions of the basin are dominated by LVB dynamics, within the tropical, subtropical, and subpolar gyres, at various depth range, depending on spatial scale considered. The w estimated field is accordingly accurate in many regions to first order, especially away from boundaries. The method offers a way to interpret vertical movements at various depths in function of the well-constrained horizontal geostrophic flow.

Poster show times:

RoomStart DateEnd Date
Foyer, Salao Nobre & tent Thu, Sep 27 2018,18:00 Thu, Sep 27 2018,20:00
Alban Lazar
LOCEAN-IPSL, Sorbonne Université