Wind-driven seasonal cycle of the atlantic meridional overturning circulation

Jian Zhao, William E Johns

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The dynamical processes governing the seasonal cycle of the Atlantic meridional overturning circulation (AMOC) are studied using a variety of models, ranging from a simple forced Rossby wave model to an eddy-resolving ocean general circulation model. The AMOC variability is decomposed into Ekman and geostrophic transport components, which reveal that the seasonality of the AMOC is determined by both components in the extratropics and dominated by the Ekman transport in the tropics. The physics governing the seasonal fluctuations of the AMOC are explored in detail at three latitudes (26.5°N, 6°N, and 34.5°S). While the Ekman transport is directly related to zonal wind stress seasonality, the comparison between different numerical models shows that the geostrophic transport involves a complex oceanic adjustment to the wind forcing. The oceanic adjustment is further evaluated by separating the zonally integrated geostrophic transport into eastern and western boundary currents and interior flows. The results indicate that the seasonal AMOC cycle in the extratropics is controlled mainly by local boundary effects, where either the western or eastern boundary can be dominant at different latitudes, while in the northern tropics it is the interior flow and its lagged compensation by the western boundary current that determine the seasonal AMOC variability.

Original languageEnglish (US)
Pages (from-to)1541-1562
Number of pages22
JournalJ. PHYSICAL OCEANOGRAPHY
Volume44
Issue number6
DOIs
StatePublished - 2014

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meridional circulation
Ekman transport
western boundary current
seasonality
eastern boundary current
wind forcing
Rossby wave
zonal wind
wind stress
general circulation model
eddy
physics
ocean

Keywords

  • Boundary currents
  • Circulation/Dynamics
  • Meridional overturning circulation
  • Rossby waves
  • Seasonal variability
  • Variability

ASJC Scopus subject areas

  • Oceanography

Cite this

Wind-driven seasonal cycle of the atlantic meridional overturning circulation. / Zhao, Jian; Johns, William E.

In: J. PHYSICAL OCEANOGRAPHY, Vol. 44, No. 6, 2014, p. 1541-1562.

Research output: Contribution to journalArticle

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