Mean meridional currents in the central and eastern equatorial Atlantic.

Perez, Renellys C., Hormann, Verena, Lumpkin, Rick, Brandt, Peter , Johns, William E., Hernandez, Fabrice, Schmid, Claudia and Bourlès, Bernard (2014) Mean meridional currents in the central and eastern equatorial Atlantic. Climate Dynamics, 43 (11). pp. 2943-2962. DOI 10.1007/s00382-013-1968-5.

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Abstract

Ship-based acoustic Doppler current profiler (ADCP) velocity measurements collected by several major field programs in the tropical Atlantic are averaged and combined with estimates of the mean near-surface velocity derived from drifters and Argo float surface drifts (ADCP+D) to describe the mean cross-equatorial and vertical structure of the meridional currents along 23°W and 10°W. Data from moored ADCPs and fixed-depth current meters, a satellite-derived velocity product, and a global ocean reanalysis were additionally used to evaluate the mean ADCP+D meridional velocity. The dominant circulation features in the long-term mean ADCP+D meridional velocity in the upper 100 m are the tropical cells (TCs) located approximately between 5°S and 5°N, with near-surface poleward flow and subsurface equatorward flow that is stronger and shallower in the northern cell compared to the southern cell. The thickness of the surface limb of the TCs decreases and the northern cell is found to shift further south of the equator from the central to eastern tropical Atlantic. Analysis of two-season means estimated from the ship-based ADCP, near-surface drift, and moored velocity data, as well as the simulated fields, indicates that the maximum poleward velocity in the surface limb of the TCs intensifies during December–May along 23°W largely due to seasonal compensation between the geostrophic and ageostrophic (or wind-driven) components of the meridional velocity, whereas the maximum equatorward flow in the subsurface limb of the northern cell intensifies during June–November along both 23°W and 10°W due to the seasonality of the geostrophic meridional velocity.

Document Type: Article
Funder compliance: info:eu-repo/grantAgreement/EC/FP7/218812
Additional Information: This paper is a contribution to the special issue on tropical Atlantic variability and coupled model climate biases that have been the focus of the recently completed Tropical Atlantic Climate Experiment (TACE), an international CLIVAR program (http://www.clivar.org/organization/atlantic/tace). This special issue is coordinated by William Johns, Peter Brandt, and Ping Chang, representatives of the TACE Observations and TACE Modeling and Synthesis working groups. WOS:000344862200005
Keywords: Tropical Atlantic; Meridional currents; Tropical cells
Research affiliation: OceanRep > SFB 754
OceanRep > SFB 754 > A4
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1007/s00382-013-1968-5
ISSN: 0930-7575
Projects: CLIVAR, SFB754, PIRATA, MyOcean, RACE, SFB754, TACE, Future Ocean
Expeditions/Models/Experiments:
Date Deposited: 07 Mar 2014 13:12
Last Modified: 03 Nov 2016 12:34
URI: http://oceanrep.geomar.de/id/eprint/23730

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