Reconstruction of the southern oscillation from dryness/wetness in China for the last 500 years

Examination of instrumental data shows that a close relationship exists between the Southern Oscillation Index (SOI) and precipitation in China. In order to examine the anomalies of the climate in historic time, the 500-year proxy rainfall data in China were used to reconstruct the past seasonal SOI by the canonical correlation method. The reconstructed SOIs calibrate an average of 40% of the Southern Oscillation (SO) variance with about an average of 20% of variance verified over an independent period. The results exhibit that the activity of the SO in the past was not stable and varied in several periods. The SO was more active during 1472-1544, 1626-1708, with low SOI years occurring 10-12 times per half century, and less active during 1708-1960, with low SOI years occurring 6-8 times per half century. The second half of the 20th century sees even more frequent low SOI occurrences in comparison with the past. The more frequent low SOI years appear to be associated with cooler periods in China and several other mid-latitude areas in the Northern Hemisphere. Significant spectral peaks of the SO activity are identified in a range of 2-10 years. (C) 1998 Royal Meteorological Society.