Details:

Alternative Title:
This study describes biweekly (defined as periods between 10 and 15 days) ocean variability in relation to equatorial wave theory using a comprehensive set of moored ocean current velocities as well as satellite-retrieved oceanic and atmospheric parameters in the Indian Ocean. Moored biweekly current velocities exhibit the meridional structure of mixed Rossby-gravity waves: Symmetric for meridional velocity and antisymmetric for zonal velocity around the equator with a decay scale of 228–309 km. The biweekly meridional velocity along the equator has average zonal and vertical wavelengths of 3,430 ± 550 km and 0.76 ± 0.15 km, respectively, with phase propagating westward at speeds of 2.8–3.1 m s−1 and upward at 54–56 m day−1. Conversely, wave energy is inferred to propagate eastward and downward. The range of best fit constants (1.4–2.0 m s−1) that result from the linear separation of horizontal and vertical wave structures suggests the second baroclinic wave mode is dominant over other low baroclinic modes in accounting for the velocity variability. The biweekly waves are forced by surface winds; satellite-derived wind stress, sea level, and surface current anomalies, regressed against the first principal component of the biweekly moored velocities, illustrate the basin-scale structure and temporal evolution of the waves.
Journal Title:
Journal of Geophysical Research: Oceans
Personal Author:
Pujiana, Kandaga ; McPhaden, Michael J.
Pujiana, Kandaga ; McPhaden, Michael J. Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research) ; PMEL (Pacific Marine Environmental Laboratory)
OAR (Oceanic and Atmospheric Research) ; PMEL (Pacific Marine Environmental Laboratory) Less -
Description:
This study describes biweekly (defined as periods between 10 and 15 days) ocean variability in relation to equatorial wave theory using a comprehensive set of moored ocean current velocities as well as satellite-retrieved oceanic and atmospheric parameters in the Indian Ocean. Moored biweekly current velocities exhibit the meridional structure of mixed Rossby-gravity waves: Symmetric for meridional velocity and antisymmetric for zonal velocity around the equator with a decay scale of 228–309 km. The biweekly meridional velocity along the equator has average zonal and vertical wavelengths of 3,430 ± 550 km and 0.76 ± 0.15 km, respectively, with phase propagating westward at speeds of 2.8–3.1 m s−1 and upward at 54–56 m day−1. Conversely, wave energy is inferred to propagate eastward and downward. The range of best fit constants (1.4–2.0 m s−1) that result from the linear separation of horizontal and vertical wave structures suggests the second baroclinic wave mode is dominant over other low baroclinic modes in accounting for the velocity variability. The biweekly waves are forced by surface winds; satellite-derived wind stress, sea level, and surface current anomalies, regressed against the first principal component of the biweekly moored velocities, illustrate the basin-scale structure and temporal evolution of the waves.
Keywords:
[+]
Rossby waves Equatorial Indian Ocean Equatorial Waves Mixed Rossby-gravity Waves
Source:
Journal of Geophysical Research: Oceans, 126(5)
DOI:
https://doi.org/10.1029/2020JC016840
Document Type:
Journal Article
Place as Subject:
Indian Ocean
Rights Information:
Other
Compliance:
Submitted
Main Document Checksum:
[+]
urn:sha256:459eb6af9820e905d423e661e620fe3668e5440e423bec08fdc51990a98cb8fc
Download URL:
https://repository.library.noaa.gov/view/noaa/29999/noaa_29999_DS1.pdf
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