The Angola Current: Flow and hydrographic characteristics as observed at 11°S.

Kopte, Robert, Brandt, Peter , Dengler, Marcus , Tchipalanga, P. C. M., Macuéria, M. and Ostrowski, M. (2017) The Angola Current: Flow and hydrographic characteristics as observed at 11°S. Open Access Journal of Geophysical Research: Oceans, 122 (2). pp. 1177-1189. DOI 10.1002/2016JC012374.

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The eastern boundary circulation off the coast of Angola has been described only sparsely to date, although it is a key element in the understanding of the highly productive tropical marine ecosystem off Angola. Here, we report for the first time direct velocity observations of the Angola Current (AC) at ∼11°S collected between July 2013 and October 2015 in the depth range from 45 to 450 m. The measurements reveal an alongshore flow that is dominated by intraseasonal to seasonal variability with periodically alternating southward and northward velocities in the range of ±40 cm/s. During the observation period, a weak southward mean flow of 5–8 cm/s at 50 m depth is observed, with the southward current extending down to about 200 m depth. Corresponding mean southward transport of the AC is estimated to be 0.32 ± 0.046 Sv. An extensive set of hydrographic measurements is used to investigate the thermal structure and seasonality in the hydrography of the eastern boundary circulation. Within the depth range of the AC, the superposition of annual and semiannual harmonics explains a significant part of the total variability, although salinity in the near surface layer appears to be also impacted by year-to-year variability and/or short-term freshening events. In the central water layer, temperature and salinity on isopycnals vary only weakly on seasonal to annual time scales. The available data set is further used to evaluate different reanalysis products particularly emphasizing the ocean's role in coupled climate model SST biases in the Eastern Tropical Atlantic.

Document Type: Article
Funder compliance: info:eu-repo/grantAgreement/EC/FP7/603521
Keywords: Angola Current; Southeast Atlantic Ocean; eastern boundary upwelling system; SST bias
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1002/2016JC012374
ISSN: 2169-9275
Date Deposited: 24 Feb 2017 10:28
Last Modified: 27 May 2019 09:13

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