Seasonal Mixed Layer Heat and Salinity Budget in the South Eastern Tropical Atlantic Ocean.

Lüdke, Jan , Dengler, Marcus , Brandt, Peter and Rath, Willi (2016) Seasonal Mixed Layer Heat and Salinity Budget in the South Eastern Tropical Atlantic Ocean. [Poster] In: PREFACE-PIRATA-CLIVAR-TAV Conference. , 28.11.-02.12.2016, Paris, France .

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Abstract

An extensive hydrographic dataset, compiled from public and previously unavailable archives, is used to quantify the physical processes contributing to the mixed layer heat and salinity budgets in the south eastern tropical Atlantic. This new climatology developed within the EU PREFACE project provides seasonal variations of mixed layer heat content and salinity. The surface heat and freshwater fluxes, horizontal advection from near-surface velocities, horizontal eddy advection, and vertical entrainment contributing to these variations are calculated for several subregions of the south eastern tropical Atlantic.
The most important cooling is caused by zonal heat advection in the off-equatorial areas for the whole year. Eddy advection is an additional major heat flux and provides the largest annual mean heating in the Benguela upwelling system and further offshore but exhibits large seasonal variations closer to the equator. The surface heat flux is identified as the main driver of seasonal heat content variations due to the large annual cycle of short-wave radiation. Throughout the off-equatorial areas the evaporation is larger than precipitation and their combined impact on the mixed layer salinity is balanced by zonal freshwater advection. Especially in the eastern equatorial Atlantic other oceanic processes, like entrainment and probably vertical mixing, contribute to the mixed layer salinity budget, too. However, not all regional budgets are closed within the uncertainty, therefore additional not resolved processes like vertical mixing have to close the remaining residual. In contrast to the mixed layer heat budget that is dominated by surface fluxes, the mixed layer salinity budget is more strongly influenced by ocean processes.

Document Type: Conference or Workshop Item (Poster)
Keywords: Heat Budget; Salt Budget; Mixed Layer; Tropical Atlantic; Angola; Benguela
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-TM Theory and Modeling
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Projects: PREFACE, SACUS
Date Deposited: 21 Dec 2016 11:11
Last Modified: 21 Dec 2016 11:11
URI: https://oceanrep.geomar.de/id/eprint/35352

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