- Air-sea interaction
- Air-land interaction
- Local responses
- 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.
12 correct matches from 17 predictions (significant at 92%)