On the seasonal variations of salinity of the tropical Atlantic mixed layer

Camara, I.; Kolodziejczyk, Nicolas; Mignot, Juliette; Lazar, Alban; Gaye, Amadou T. (2015). On the seasonal variations of salinity of the tropical Atlantic mixed layer. Journal of Geophysical Research: Oceans, 120(6), pp. 4441-4462. AGU 10.1002/2015JC010865

[img]
Preview
Text
jgrc21272.pdf - Published Version
Available under License Publisher holds Copyright.

Download (10MB) | Preview

The physical processes controlling the mixed layer salinity (MLS) seasonal budget in the tropical Atlantic Ocean are investigated using a regional configuration of an ocean general circulation model. The analysis reveals that the MLS cycle is generally weak in comparison of individual physical processes entering in the budget because of strong compensation. In evaporative regions, around the surface salinity maxima, the ocean acts to freshen the mixed layer against the action of evaporation. Poleward of the southern SSS maxima, the freshening is ensured by geostrophic advection, the vertical salinity diffusion and, during winter, a dominant contribution of the convective entrainment. On the equatorward flanks of the SSS maxima, Ekman transport mainly contributes to supply freshwater from ITCZ regions while vertical salinity diffusion adds on the effect of evaporation. All these terms are phase locked through the effect of the wind. Under the seasonal march of the ITCZ and in coastal areas affected by river (7°S:15°N), the upper ocean freshening by precipitations and/or runoff is attenuated by vertical salinity diffusion. In the eastern equatorial regions, seasonal cycle of wind forced surface currents advect freshwaters, which are mixed with subsurface saline water because of the strong vertical turbulent diffusion. In all these regions, the vertical diffusion presents an important contribution to the MLS budget by providing, in general, an upwelling flux of salinity. It is generally due to vertical salinity gradient and mixing due to winds. Furthermore, in the equator where the vertical shear, associated to surface horizontal currents, is developed, the diffusion depends also on the sheared flow stability.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Climate and Environmental Physics
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)

UniBE Contributor:

Mignot, Juliette

Subjects:

500 Science > 530 Physics

ISSN:

2169-9275

Publisher:

AGU

Language:

English

Submitter:

Monika Wälti-Stampfli

Date Deposited:

20 Aug 2015 11:42

Last Modified:

20 Dec 2015 02:30

Publisher DOI:

10.1002/2015JC010865

BORIS DOI:

10.7892/boris.71036

URI:

https://boris.unibe.ch/id/eprint/71036

Actions (login required)

Edit item Edit item
Provide Feedback