Observed Agulhas Current sensitivity to interannual and long-term trend atmospheric forcings

Shane Elipot, Lisa Beal

Research output: Contribution to journalArticle

3 Citations (Scopus)

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 languageEnglish (US)
Pages (from-to)3077-3098
Number of pages22
JournalJournal of Climate
Volume31
Issue number8
DOIs
StatePublished - Apr 1 2018
Externally publishedYes

Fingerprint

atmospheric forcing
El Nino-Southern Oscillation
satellite altimetry
Southern Hemisphere
climate modeling
oscillation
climate
long-term trend
trend
in situ
index
product

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.

In: Journal of Climate, Vol. 31, No. 8, 01.04.2018, p. 3077-3098.

Research output: Contribution to journalArticle

@article{257362e01c5542428679cf684aab306e,
title = "Observed Agulhas Current sensitivity to interannual and long-term trend atmospheric forcings",
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.",
keywords = "Antarctic Oscillation, Boundary currents, ENSO, Indian Ocean, Southern Hemisphere, Transport",
author = "Shane Elipot and Lisa Beal",
year = "2018",
month = "4",
day = "1",
doi = "10.1175/JCLI-D-17-0597.1",
language = "English (US)",
volume = "31",
pages = "3077--3098",
journal = "Journal of Climate",
issn = "0894-8755",
publisher = "American Meteorological Society",
number = "8",

}

TY - JOUR

T1 - Observed Agulhas Current sensitivity to interannual and long-term trend atmospheric forcings

AU - Elipot, Shane

AU - Beal, Lisa

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

VL - 31

SP - 3077

EP - 3098

JO - Journal of Climate

JF - Journal of Climate

SN - 0894-8755

IS - 8

ER -