On the meridional ageostrophic transport in the tropical Atlantic.

Fu, Yao, Karstensen, Johannes and Brandt, Peter (2017) On the meridional ageostrophic transport in the tropical Atlantic. Open Access Ocean Science, 13 (4). pp. 531-549. DOI 10.5194/os-13-531-2017.

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Supplementary data:

Abstract

The meridional Ekman volume, heat, and salt transport across two trans-Atlantic sections near 14.5° N and 11° S were estimated using in situ observations, wind products, and model data. A meridional ageostrophic velocity was obtained as the difference between the directly measured total velocity and the geostrophic velocity derived from observations. Interpreting the section mean ageostrophy to be the result of an Ekman balance, the meridional Ekman transport of 6. 2 ± 2. 3 Sv northward at 14.5° N and 11. 7 ± 2. 1 Sv southward at 11° S is estimated. The integration uses the top of the pycnocline as an approximation for the Ekman depth, which is on average about 20 m deeper than the mixed layer depth. The Ekman transport estimated based on the velocity observations agrees well with the predictions from in situ wind stress data of 6. 7 ± 3. 5 Sv at 14.5° N and 13. 6 ± 3. 3 Sv at 11° S. The meridional Ekman heat and salt fluxes calculated from sea surface temperature and salinity data or from high-resolution temperature and salinity profile data differ only marginally. The errors in the Ekman heat and salt flux calculation were dominated by the uncertainty of the Ekman volume transport estimates.

Document Type: Article
Additional Information: Data availability: The Level-4 Near-real-time wind stress product is available at http://marine.copernicus.eu/. The NCEP/NCAR monthly wind stress data is available at http://rda.ucar.edu/datasets/ds090.2/. The NCEP/CFSR 6-h wind stress data is available at http://rda.ucar.edu/datasets/ds093.0/. The Reomich-Gilson monthly Argo climatology is available at http://sio-argo.ucsd.edu/RG_Climatology.html. The GECCO2 ocean synthesis is available at http://icdc.cen.uni-hamburg.de/1/projekte/easy-init/easy-initocean.html#c2231. The world Ocean Atlas temperature and salinity data is available at https://www.nodc.noaa.gov/OC5/woa13/. The shipboard measurements during cruise M96, M97, and M98 will be available through PANGEA, the DOI is under approval.
Keywords: 1995 SOUTHWEST MONSOON; OVERTURNING CIRCULATION; EKMAN BALANCE; HEAT-FLUX; NORTH-ATLANTIC; ARABIAN SEA; WORLD OCEAN; TEMPERATURE; VARIABILITY; 26.5-DEGREES-N
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/os-13-531-2017
ISSN: 1812-0784
Related URLs:
Projects: FOR1740, RACE, SACUS
Expeditions/Models/Experiments:
Date Deposited: 09 Jan 2017 09:12
Last Modified: 29 May 2019 11:02
URI: http://oceanrep.geomar.de/id/eprint/35508

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