Estimating the velocity and transport of Western Boundary current systems: A case study of the East Australian Current near Brisbane

TitleEstimating the velocity and transport of Western Boundary current systems: A case study of the East Australian Current near Brisbane
Publication TypeJournal Article
Year of Publication2018
AuthorsZilberman N.V, Roemmich D.H, Gille ST, Gilson J.
JournalJournal of Atmospheric and Oceanic Technology
Volume35
Pagination1313-1329
Date Published2018/06
Type of ArticleArticle
ISBN Number0739-0572
Accession NumberWOS:000438020400010
Keywordsagulhas current; array; Boundary currents; Engineering; gulf-stream; kuroshio; mean; Meteorology & Atmospheric Sciences; ocean; overturning circulation; Pacific Ocean; shallow; south-pacific ocean; structure; topography; variability
Abstract

Western boundary currents (WBCs) are highly variable narrow meandering jets, making assessment of their volume transports a complex task. The required high-resolution temporal and spatial measurements are available only at a limited number of sites. In this study a method is developed for improving estimates of the East Australian Current (EAC) mean transport and its low-frequency variability, using complementary modern datasets. The present calculation is a case study that will be extended to other subtropical WBCs. The method developed in this work will reduce uncertainties in estimates of the WBC volume transport and in the interannual mass and heat budgets of the meridional overturning circulations, improving our understanding of the response of WBCs to local and remote forcing on long time scales. High-resolution expendable bathythermograph (HR-XBT) profiles collected along a transect crossing the EAC system near Brisbane, Australia, are merged with coexisting profiles and parking-depth trajectories from Argo floats, and with altimetric sea surface height data. Using HR-XBT/Argo/altimetry data combined with Argo trajectory-based velocities at 1000 m, the 2004-15 mean poleward alongshore transport of the EAC is 19.5 +/- 2.0 Sv (1 Sv 10(6) m(3) s(-1)) of which 2.5 +/- 0.5 Sv recirculate equatorward just offshore of the EAC. These transport estimates are consistent in their mean and variability with concurrent and nearly collocated moored observations at 27 degrees S, and with earlier moored observations along 30 degrees S. Geostrophic transport anomalies in the EAC system, including the EAC recirculation, show a standard deviation of +/- 3.1 Sv at interannual time scales between 2004 and 2015.

DOI10.1175/jtech-d-17-0153.1
Short TitleJ. Atmos. Ocean. Technol.
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