ON THE ABNORMAL SWING OF THE AVERAGED TIME SERIES PRODUCED FROM A NUMBER OF CORRELATED TIME SERIES

In many climatological researches,the averaged time series can be produced from a number of time series to enhance common signals.The abnormal swing always exists in the averaged series,so that the changes of the former part of the series,with less samples,are larger than those of the latter part,with more samples.This phenomenon could be found either in tree ring chronologies produced from tree ring series with different lengths or in the averaged time series of some climatic parameters produced from records of meteorological station network.