North Atlantic Oscillation

Observed data . Reanalysis . Satellite data . Model  results NAO

NAO signal

Climate prediction problem

Anolog technique

Data Analysis

Climate variability

Climate predictability


  • The basic element of the multifield analog approach is the definition of a climate state vector which traces the time evolution of the analysed climate system in a multi-dimensional state space (Barnett and Presisendorfer, 1978)
  • The climate state vector components: anomalies of temperature at 1000 hPa, geopotential height at the 700 hPa over the Northern Hemisphere, zonal wind at 200 hPa and sea surface temperature have been used to compute a multifield correlation matrix for November.
  •  Predictand: the NAO phase (50% percentile of the NAO index built as the diffrerence between Iceland and Azores.
  • Hindcast period: 1986-2002.
  • The analogs are selected by searching the smallest distance between the actual and past states in the climate hyperspace spanned by the first 3 EOFs of the correlation matrix associated to the climate vector components.

Results: 12 correct matches from 17 predictions (significant at 92%)


Barnett, T.P. and R.W. Preisendorfer. 1978. Multifield analog prediction of short-term climate fluctuations using a climate state vector. J. Atmos. Sci., 35(10), 17711787.









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