Abstract
Of the interannual variance of the Agulhas Current transport, 29% can be linearly related to six modes of Southern Hemisphere atmospheric variability. Agulhas Current transport is quantified by a 24-yr proxy constructed using satellite altimetry and in situ data, while atmospheric variability is represented by two reanalysis products. The two leading modes of atmospheric variability, each explaining 5% of the variance of the Agulhas Current, can be described as a tropical Indo-Pacific mode, strongly correlated to ENSO, and a subtropical-subpolar mode, strongly correlated with the SAM. ENSO alone can explain 11.5% of Agulhas transport variance, yet SAM alone has no significant correlation. The remaining four atmospheric modes are not related to common climate indices and together they explain 19% of Agulhas variance, describing decadal oscillations. In previous studies using reanalyses and climate models it has been suggested that the Agulhas Current is intensifying in response to a strengthening and poleward shift of the westerlies, expressed by a positive trend in the SAM. Here, the authors find that, given its apparent weak sensitivity to the SAM, the increase in SAM over the past 24 years does not lead to a detectable trend in Agulhas Current transport.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3077-3098 |
| Number of pages | 22 |
| Journal | Journal of Climate |
| Volume | 31 |
| Issue number | 8 |
| DOIs | |
| State | Published - Apr 1 2018 |
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Keywords
- Antarctic Oscillation
- Boundary currents
- ENSO
- Indian Ocean
- Southern Hemisphere
- Transport
ASJC Scopus subject areas
- Atmospheric Science
Cite this
Observed Agulhas Current sensitivity to interannual and long-term trend atmospheric forcings. / Elipot, Shane; Beal, Lisa M.
In: Journal of Climate, Vol. 31, No. 8, 01.04.2018, p. 3077-3098.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Observed Agulhas Current sensitivity to interannual and long-term trend atmospheric forcings
AU - Elipot, Shane
AU - Beal, Lisa M.
PY - 2018/4/1
Y1 - 2018/4/1
N2 - Of the interannual variance of the Agulhas Current transport, 29% can be linearly related to six modes of Southern Hemisphere atmospheric variability. Agulhas Current transport is quantified by a 24-yr proxy constructed using satellite altimetry and in situ data, while atmospheric variability is represented by two reanalysis products. The two leading modes of atmospheric variability, each explaining 5% of the variance of the Agulhas Current, can be described as a tropical Indo-Pacific mode, strongly correlated to ENSO, and a subtropical-subpolar mode, strongly correlated with the SAM. ENSO alone can explain 11.5% of Agulhas transport variance, yet SAM alone has no significant correlation. The remaining four atmospheric modes are not related to common climate indices and together they explain 19% of Agulhas variance, describing decadal oscillations. In previous studies using reanalyses and climate models it has been suggested that the Agulhas Current is intensifying in response to a strengthening and poleward shift of the westerlies, expressed by a positive trend in the SAM. Here, the authors find that, given its apparent weak sensitivity to the SAM, the increase in SAM over the past 24 years does not lead to a detectable trend in Agulhas Current transport.
AB - Of the interannual variance of the Agulhas Current transport, 29% can be linearly related to six modes of Southern Hemisphere atmospheric variability. Agulhas Current transport is quantified by a 24-yr proxy constructed using satellite altimetry and in situ data, while atmospheric variability is represented by two reanalysis products. The two leading modes of atmospheric variability, each explaining 5% of the variance of the Agulhas Current, can be described as a tropical Indo-Pacific mode, strongly correlated to ENSO, and a subtropical-subpolar mode, strongly correlated with the SAM. ENSO alone can explain 11.5% of Agulhas transport variance, yet SAM alone has no significant correlation. The remaining four atmospheric modes are not related to common climate indices and together they explain 19% of Agulhas variance, describing decadal oscillations. In previous studies using reanalyses and climate models it has been suggested that the Agulhas Current is intensifying in response to a strengthening and poleward shift of the westerlies, expressed by a positive trend in the SAM. Here, the authors find that, given its apparent weak sensitivity to the SAM, the increase in SAM over the past 24 years does not lead to a detectable trend in Agulhas Current transport.
KW - Antarctic Oscillation
KW - Boundary currents
KW - ENSO
KW - Indian Ocean
KW - Southern Hemisphere
KW - Transport
UR - http://www.scopus.com/inward/record.url?scp=85047061027&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85047061027&partnerID=8YFLogxK
U2 - 10.1175/JCLI-D-17-0597.1
DO - 10.1175/JCLI-D-17-0597.1
M3 - Article
AN - SCOPUS:85047061027
VL - 31
SP - 3077
EP - 3098
JO - Journal of Climate
JF - Journal of Climate
SN - 0894-8755
IS - 8
ER -