The daily AAO index is constructed by projecting the daily (00Z) 700mb height anomalies poleward of 20°S onto the loading pattern of the AAO. Please note that year-round monthly mean anomaly data has been used to obtain the loading pattern of the AAO (Methodology). Since the AAO has the largest variability during the cold sesaon, the loading pattern primarily captures characteristics of the cold season AAO pattern.
The daily AAO index and its forecasts using MRF and Ensemble mean forecast data are shown for the previous 120 days as indicated and they are normalized by standard deviation using 1979-2000 base period. A 3-day running mean is applied for the forecast indices.