SOME LONG-RUN PROPERTIES OF RAINFALL RECORDS IN ITALY

Six rainfall data time series, collected in various sites in Italy, ar e analyzed in order to determine whether a linear trend or long memory is present. Various techniques for estimating the intensity of long m emory are applied, including the rescaled range statistic, the aggrega ted variance method, the periodogram method and maximum likelihood. A modified variance-type estimator is used in order to detect long memor y even when some types of nonstationarity are potentially present. The results indicate that a decreasing trend, though not statistically si gnificant, is present in every record, and that long memory is signifi cant in only two series.