indice de l'oscillation australe positif

OBS: Indice de l'oscillation australe, d'après G. Walker, signalant un état de l'atmosphère tel que la différence de pressions, entre la partie ouest et la partie est du Pacifique, est supérieure à la normale.
OBS: On associe les épisodes ""La Nina"" à un indice de l'oscillation australe positif ou élevé.

CONT: Historical records of the Southern Oscillation index and of the sea-surface temperature off the Peruvian coast show the two variables are linked, although the association is not perfect. The Southern Oscillation index is calculated by subtracting the atmospheric surface pressure at Darwin, Australia, from the pressure at Easter Island. When the index is positive, the east-west pressure gradient is greater than normal and the trade winds are stronger; conversely, a negative index indicates weak trade winds.