ADJUSTMENT OF TEMPERATURE AND RAINFALL RECORDS FOR SITE CHANGES

Methods are presented for estimating the effect of known site changes on temperature and rainfall measurements. Parallel cumulative sums of seasonally adjusted series from neighbouring stations are a useful exp loratory tool for recognizing site-change effects at a station that ha s a number of near neighbours. For temperature data, a site-change eff ect can be estimated by a difference between the target station and we ighted mean of neighbouring stations, comparing equal periods before a nd after the site change. For rainfall the method is similar, except f or a logarithmic transformation. Examples are given. In the case of is olated stations, the estimation is necessarily more subjective, but a variety of graphical and analytical techniques are useful aids for dec iding how to adjust for a site change.