TY - JOUR
T1 - Spin-Up of the Southern Hemisphere Super Gyre
AU - Qu, Tangdong
AU - Fukumori, Ichiro
AU - Fine, Rana A.
N1 - Funding Information:
This study was supported by National Aeronautics and Space Administration through grant NNX16AH86G and by National Science Foundation through grants 1829809 and 1433922. The AVISO data were obtained from https://www.aviso.altimetry.fr/, the gridded Argo data and NCEP reanalysis wind products were obtained from http://apdrc.soest.hawaii.edu/, and the ECCO outputs were obtained from http://ecco.jpl.nasa.gov/. The authors are grateful to N. Schneider for useful discussions on the topic and to the two anonymous reviewers for thoughtful comments and constructive suggestions on an earlier version of the manuscript.
PY - 2019/1
Y1 - 2019/1
N2 - This study investigates the variability of the Southern Hemisphere super gyre (SHSG), using remotely sensed altimeter measurements, in situ Argo observations, and results from an ocean state estimate of the Consortium for Estimating the Circulation and Climate of the Ocean. Analyses of altimeter data show large trends of sea surface height, and their positive-negative contrast suggests a strengthening of subtropical gyres in all the three Southern Hemisphere oceans since 1993. Analyses of Argo data and the Estimating the Circulation and Climate of the Ocean estimate indicate that these dynamic signals of southern subtropical gyres extend to at least 2,000 m. The three southern subtropical gyres are interconnected through the Tasman and Agulhas leakages and vary consistently during the period 1993–2016. The Tasman and Agulhas leakages also show an increasing trend of inter-ocean water exchange with a typical increase of ~2 Sv (1 Sv = 10 6 m 3 /s) per decade, indicative of a two-decade-long spin-up of the SHSG. The strengthening and poleward shift of westerly winds are associated with an increasing southern annular mode, which affect the midlatitude and high-latitude Southern Hemisphere oceans and contribute to the spin-up of the SHSG.
AB - This study investigates the variability of the Southern Hemisphere super gyre (SHSG), using remotely sensed altimeter measurements, in situ Argo observations, and results from an ocean state estimate of the Consortium for Estimating the Circulation and Climate of the Ocean. Analyses of altimeter data show large trends of sea surface height, and their positive-negative contrast suggests a strengthening of subtropical gyres in all the three Southern Hemisphere oceans since 1993. Analyses of Argo data and the Estimating the Circulation and Climate of the Ocean estimate indicate that these dynamic signals of southern subtropical gyres extend to at least 2,000 m. The three southern subtropical gyres are interconnected through the Tasman and Agulhas leakages and vary consistently during the period 1993–2016. The Tasman and Agulhas leakages also show an increasing trend of inter-ocean water exchange with a typical increase of ~2 Sv (1 Sv = 10 6 m 3 /s) per decade, indicative of a two-decade-long spin-up of the SHSG. The strengthening and poleward shift of westerly winds are associated with an increasing southern annular mode, which affect the midlatitude and high-latitude Southern Hemisphere oceans and contribute to the spin-up of the SHSG.
KW - Agulhas leakage
KW - Southern Hemisphere super gyre
KW - Tasman leakage
KW - southern annular mode
KW - westerly winds
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U2 - 10.1029/2018JC014391
DO - 10.1029/2018JC014391
M3 - Article
AN - SCOPUS:85059654578
VL - 124
SP - 154
EP - 170
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
SN - 2169-897X
IS - 1
ER -