Storm-track acitivity (bandpass-filtered Z500): ensemble spread

JJA

AMIP Short coupled Short coupled anom AMIP-Nor AMIP-Nor anom

SON

AMIP Short coupled Short coupled anom AMIP-Nor AMIP-Nor anom

DJF

AMIP Short coupled Short coupled anom AMIP-Nor AMIP-Nor anom

MAM

AMIP Short coupled Short coupled anom AMIP-Nor AMIP-Nor anom