On the lowfrequency variability in the Indian Ocean

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• On the low-frequency variability in the Indian
  Ocean

Irina Sakova, Gary Meyers and Richard Coleman
CSIRO Wealth from Ocean Flagship UniTas
Quantitative Marine Science PhD Program
23 August 2005 Dynamic Planet 2005, Cairns
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This work investigates low-frequency variability
in the Indian Ocean Data used AVISO
satellite altimetry sea surface height (SSH)
ERS/Envisat/TOPEX/Jason-1 gridded 1.0
(1992-2004) expendable bathy-thermograph
(XBT) temperature data (1989-2002) Main
analysis methods Fourier Transform
FFT/inverse FFT Bandpass Filtering
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• Main findings
• Four dominant frequencies bands are identified,
• corresponding to the well known semi-annual and
  annual cycles and two bands in the lower
  frequencies separated by a significant spectral
  gap.
• These frequencies are
• 6 months
• 12 months
• 18-20 months
• more then 2 years