Abstract :
The North Pacific centre appears to be the weakest link in the concept of the Arctic Oscillation (AO), mainly because
of its very low correlations with the other two centres, located over the Arctic and in the North Atlantic. Its latitudinal
position and horizontal extent differ considerably in dependence on whether a covariance or correlation matrix is used
as an input to principal component analysis. In the correlation-based analysis, the Pacific centre is much weaker and
shifted 15◦ southwards. The teleconnectivity of the Pacific centre in the covariance- and correlation-based solutions is
widely dissimilar. The coincidence of the covariance-based Pacific centre with an area of a high local variability and
the lack of its correlations with remote areas imply that the Pacific centre of the AO is a result of a high local variability
rather than teleconnectivity. This idea is supported by a simple three-component artificial example.
