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Alternative Title:
The semiannual Rossby wave in the equatorial Indian Ocean is analyzed using 1,000-dbar horizontal drift and 3-D isotherm displacement data from Argo floats. The strong semiannual variations in zonal velocity associated with this wave that have been previously studied are confirmed here, and a more complete picture of the wave is provided with the addition of the 1,000-dbar meridional velocities and 0- to 2,000-dbar isotherm displacements. At 1,000 dbar, semiannual variations in each field are consistent with Rossby wave physics: Zonal velocity is maximal on the equator, isotherm displacement and meridional velocity extrema are colocated with equatorially symmetric zonal velocity phase reversals near ±2.5° in latitude, and all three fields propagate westward over the year. The latitudinal structure of the meridional velocities in the central and eastern Indian Ocean hints at Rossby wave energy in higher meridional modes than the first, but that signature is not apparent in the isotherm displacements or the zonal velocities. With upward and westward phase propagation and downward and westward energy propagation, isotherm displacement vertical sections confirm the presence of a vertically propagating wave that reaches to at least 2,000 dbar, the deepest extent of the Argo floats.
Journal Title:
Journal of Geophysical Research: Oceans
Personal Author:
Zanowski, Hannah ; Johnson, Gregory C.
Zanowski, Hannah ; Johnson, Gregory C. Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research) ; PMEL (Pacific Marine Environmental Laboratory) ; CICOES (Cooperative Institute for Climate, Ocean and Ecosystem Studies)
OAR (Oceanic and Atmospheric Research) ; PMEL (Pacific Marine Environmental Laboratory) ; CICOES (Cooperative Institute for Climate, Ocean and Ecosystem Studies) Less -
Description:
The semiannual Rossby wave in the equatorial Indian Ocean is analyzed using 1,000-dbar horizontal drift and 3-D isotherm displacement data from Argo floats. The strong semiannual variations in zonal velocity associated with this wave that have been previously studied are confirmed here, and a more complete picture of the wave is provided with the addition of the 1,000-dbar meridional velocities and 0- to 2,000-dbar isotherm displacements. At 1,000 dbar, semiannual variations in each field are consistent with Rossby wave physics: Zonal velocity is maximal on the equator, isotherm displacement and meridional velocity extrema are colocated with equatorially symmetric zonal velocity phase reversals near ±2.5° in latitude, and all three fields propagate westward over the year. The latitudinal structure of the meridional velocities in the central and eastern Indian Ocean hints at Rossby wave energy in higher meridional modes than the first, but that signature is not apparent in the isotherm displacements or the zonal velocities. With upward and westward phase propagation and downward and westward energy propagation, isotherm displacement vertical sections confirm the presence of a vertically propagating wave that reaches to at least 2,000 dbar, the deepest extent of the Argo floats.
Keywords:
[+]
Argo Equatorial Indian Ocean Isotherm Displacements Rossby Waves Semiannual Velocity Variability
Source:
Journal of Geophysical Research: Oceans, 124(12), 9507-9516
DOI:
https://doi.org/10.1029/2019JC015342
Document Type:
Journal Article
Funding:
Grant no. NA15OAR4320063
Place as Subject:
Indian Ocean
Rights Information:
Other
Compliance:
Submitted
Main Document Checksum:
[+]
urn:sha256:2c5557cfe40737ac9f7cbb81ed08f490a421cb21213930ea8aad97455debc7fe
Download URL:
https://repository.library.noaa.gov/view/noaa/30022/noaa_30022_DS1.pdf
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