Fig. 2: Seasonal evolution of the stratospheric changes associated with the AMV in the NCEP-reanalysis.

a, b Seasonal evolution of the multidecadal NAM indices between 1000 and 10 hPa for strong multidecadal positive (1989–1992) and negative (1959–1962) NAO-phases, respectively. c, d The evolution of the lower stratospheric temperature (100–70 hPa) associated with a and b, respectively (in °C).