¥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