Monthly ozone anomalies (percent) from the long term monthly
means for five zones: 50N-30N (NH mid-latitudes), 25N-10N (NH tropical
surf zone), 10N-10S (Equatorial-QBO zone), 10S-25S (SH tropical surf
zone), and 30S-50S (SH mid-latitudes). The long term monthly means are
determined from the entire data set beginning in 1979.