Space-time analysis of sea level in the North Atlantic from TOPEX/Poseidon satellite altimetry

  • S. M. Barbosa
  • M. J. Fernandes
  • M. E. Silva
Conference paper
Part of the International Association of Geodesy Symposia book series (IAG SYMPOSIA, volume 129)


Spatial and temporal sea level variability in the North Atlantic is investigated from Topex/Poseidon (T/P) altimetry data. Time series of sea level anomalies on a regular 5° grid are analysed. Non-linear denoising through thresholding in the wavelet transform domain is carried out for each series in order to remove noise while preserving non-smooth features. Principal Component Analysis (PCA) is used to obtain a spatio-temporal description of the sea level field. To avoid modal mixing and improve interpretation of the principal modes, PCA is implemented separately for seasonal and trend components of the sea level field obtained from a wavelet-based multiresolution analysis. The leading pattern of the seasonal field reflects the dominance of a stable annual cycle over the study area and the change in the seasonal regime approaching the equator with contribution of the semi-annual cycle and phaseshift in the annual cycle in the tropical Atlantic. The leading pattern of the trend field is a broad spatial pattern associated with North Atlantic Oscillation (NAO), reflecting the influence of atmospheric conditions on interannual sea level variability.


satellite altimetry sea level change discrete wavelet transform PCA 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2005

Authors and Affiliations

  • S. M. Barbosa
    • 1
  • M. J. Fernandes
    • 1
  • M. E. Silva
    • 1
  1. 1.Department of Applied Mathematics, Faculdade de CiênciasUniversidade do PortoPortoPortugal

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