The present study uses a ne scale data set from GATE ph e III to investigate spatial e ects on rainfall characteristics and its lagged autocorrelation. Due to the ner structure of the present data set, the physical processes invloved for a shorter distance scale can be identi ed, which has crucial information in the estimation r the sampling errors of a rain eld.
It is found that for a rainrate less than 4 mm/hr, a 1 km by 1° and 4 km by 4° data set will not make any noticeable di erence to accumulated rainfall statis tics. This is directly implied by stratiform rainfall sociated with the mesoscale c culation system. The rainfall within that physical region is continuous with a rainrate less than 6 mm/hr. A rainfall rate greater than 40 mm/hr contributes 20 % to the total rainfall in 1 km by 1° data, in contr t to an 8 % contribution om the 4 km by 4° data. The area-averaged processes suppress extreme rainfall considerably (the extreme would have come om the convective scale).
The variance and the autocorrelation calculated in this study reveal that the slope of the variance and autocorrelation r a smaller scale are di erent om those estimated through a larger area data. This is an indication that the convective scale rainfall eld caused this change, and the existence of a horizontal integral length scale r the shorter scale end is postulated. The implications of a horizontal integral length scale and suggestions for further research are discussed.