Seasonal and interannual variation in the cross-equatorial meridional currents observed in the eastern Indian Ocean

Observations from moored subsurface acoustic Doppler current profilers (ADCPs) have revealed the structure of cross‐equatorial meridional currents in the eastern equatorial Indian Ocean. Using observational data longer than 8 years, we present observations of the seasonal and interannual variation i...

Full description

Saved in:
Bibliographic Details
Published in:Journal of geophysical research. Oceans 2013-12, Vol.118 (12), p.6658-6671
Main Authors: Horii, T., Mizuno, K., Nagura, M., Miyama, T., Ando, K.
Format: Article
Language:English
Subjects:
ADCP
cross-equatorial currents
Earth, ocean, space
Ekman transport
El Nino
Exact sciences and technology
External geophysics
Geophysics
Heat transport
Indian Ocean
Marine
Monsoons
Ocean currents
Oceanography
Physics of the oceans
Seasonal variations
Southern Oscillation
Summer
Surface flow
Trade winds
Transport
tropical Indian Ocean
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Observations from moored subsurface acoustic Doppler current profilers (ADCPs) have revealed the structure of cross‐equatorial meridional currents in the eastern equatorial Indian Ocean. Using observational data longer than 8 years, we present observations of the seasonal and interannual variation in the cross‐equatorial currents in the 2000s. In line with earlier observations and numerical simulations, there were significant subsurface currents that displayed seasonal variation. The annual mean condition was dominated by currents during the boreal summer monsoon in which the Ekman transports are southward on both sides of the equator. The vertical structure of the mean meridional current displayed evidence of a shallow “equatorial roll,” consisting of northward surface flow and southward subsurface flow above the base of the isothermal mixed layer. The seasonal variation in upper 120 m meridional transport can be explained by wind‐driven cross‐equatorial Ekman/Sverdrup transport. Interannual variability was higher in the winter monsoon period than in the summer monsoon. The interannual variation could be related to the Pacific El Niño/Southern Oscillation (ENSO). ENSO‐induced variation in the southeasterly trade wind could modulate meridional Sverdrup transport. Implications of these observational results for meridional heat transport are discussed. Key Points Cross‐equatorial currents are observed in the eastern Indian Ocean Their seasonal variation is controlled by the zonal wind‐stress forcing Their interannual variation is associated with remote forcing by ENSO
ISSN:2169-9275
2169-9291
DOI:10.1002/2013JC009291