Subsurface equatorial zonal current in the eastern Indian Ocean

Iskandar, Iskhaq and Masumoto, Y and Mizuno, Keisuke (2009) Subsurface equatorial zonal current in the eastern Indian Ocean. JOURNAL OF GEOPHYSICAL RESEARCH, 114. ISSN doi:10.1029 /2008JC005188


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Variations of subsurface zonal current in the eastern equatorial Indian Ocean are investigated by examining 6-year data (December 2000?November 2006) from acoustic Doppler current profiler (ADCP) mooring at 0_S, 90_E. The analysis indicates the presence of an eastward equatorial subsurface current between 90 and 170 m depths during both boreal winter and summer. During boreal winter, the generation of eastward pressure gradient, which drives an eastward flow in the thermocline, is caused primarily by upwelling equatorial Kelvin waves excited by prevailing easterly winds. On the other hand, the downwelling Rossby waves generated by the reflection of the spring downwelling Kelvin waves in the eastern boundary, as well as the upwelling equatorial Kelvin waves triggered by easterlies, create an oceanic state that favors the generation of the eastward pressure gradient during boreal summer. The subsurface current reveals a distinct seasonal asymmetry. The maximum eastward speed of 63 cm s-1 is observed in April, and secondary maximum of 49 cm s-1 is seen in October. The zonal transport per unit width within depth of the subsurface current exhibits similar variations: reaching maximum eastward transport of 35 m2s-1 in April and secondary maximum of 29 m2s-1 in October. Moreover, the subsurface current during boreal summer undergoes significant interannual variations; it was absent in 2003, but it was anomalously strong during 2006.

Item Type: Article
Uncontrolled Keywords: Iskandar, I., Y. Masumoto, and K. Mizuno (2009), Subsurface equatorial zonal current in the eastern Indian Ocean, J. Geophys. Res., 114, C06005, doi:10.1029/2008JC005188.
Subjects: Q Science > QC Physics > QC1-999 Physics
Divisions: 08-Faculty of Mathematics and Natural Science > 45201-Physics (S1)
Depositing User: Dr. Iskhaq Iskandar
Date Deposited: 27 Sep 2019 06:41
Last Modified: 27 Sep 2019 06:41

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