¥The
data are monthly mean streamfunction for extended
winter (includes March), from 1979 to 1997, for the whole
NH from the ECMWF reanalysis (ERA)
¥Some
preprocessing has taken place – removing annual cycle
¥EOFs
are often interpreted as Ôphysical modesÕ and
there is considerable argument over which EOFs
correspond to such modes, and whether EOFs can find
them, or even whether they exist