HR: 0800h
AN: OS41B-0540    [Abstracts]
TI: Spectral estimates of the first few Rossby wave baroclinic modes in the South Pacific Ocean from satellite altimeters and testing of theories against these observations
AU: * Maharaj, A M
EM: angela.maharaj@mq.edu.au
AF: Macquarie University, Division of Environmental and Life Sciences, Sydney, NSW 2109, Australia
AU: Cipollini, P
EM: cipo@noc.soton.ac.uk
AF: National Oceanography Centre, Southampton, European Way, Southampton, SO143ZH, United Kingdom
AU: Holbrook, N J
EM: neil.holbrook@mq.edu.au
AF: Macquarie University, Division of Environmental and Life Sciences, Sydney, NSW 2109, Australia
AU: Killworth, P D
EM: pki@noc.soton.ac.uk
AF: National Oceanography Centre, Southampton, European Way, Southampton, SO143ZH, United Kingdom
AU: Blundell, J R
EM: jeff@noc.soton.ac.uk
AF: National Oceanography Centre, Southampton, European Way, Southampton, SO143ZH, United Kingdom
AB: Previous literature has suggested that multiple peaks in sea level anomalies (SLA) detected by two-dimensional Fourier transform (2D-FT) analysis are spectral components of multiple propagating signals which may correspond to different baroclinic Rossby wave modes. We test this hypothesis in the South Pacific Ocean by applying a 2D-FT analysis to the long Rossby wave signal determined from filtered TOPEX/Poseidon and ERS- 1/2 satellite altimeter derived SLA. The first four baroclinic mode dispersion curves for the classical linear wave theory and the Killworth and Blundell extended theory are used to determine the spectral signature and energy contributions of each mode. South of 17°S, the first two extended theory modes explain up to 60% more of the variance in the observed power spectral energy than their classical linear theory counterparts. The second mode contributes significantly over most of the basin. The third mode is also evident in some localised regions of the South Pacific but may be ignored at the large scale. Examination of a selection of case study sites suggest that bathymetric effects may dominate at longer wavelengths, or permit higher order mode solutions but mean flow tends to be the more influential factor in the extended theory. This study also examines the prevalence and characteristics of multiple propagating signals in the South Pacific SLA using the two-dimensional Radon Transform (2D-RT). Primary Radon Transform (RT) and Fourier Transform (FT) peaks generally compared well to each other and to the extended theory first baroclinic mode for most of the domain. A comparison to the energy ratios for the first four FT baroclinic modes showed that while the number of modes in their FT and peaks in the RT analysis coincided, the actual spatial distribution and relative contribution of these was not as consistent. Strong similarities existed in the spatial location and energy contribution between RT peaks 1 and 2 and FT modes 1 and 2. We conclude that the first and second peaks in the RT are most likely to be the signature of long Rossby waves but the dynamics behind subsequent peaks is not as clear.
DE: 4513 Decadal ocean variability (1616, 1635, 3305, 4215)
DE: 4544 Internal and inertial waves
DE: 4554 Planetary waves
DE: 4562 Topographic/bathymetric interactions
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting