Rainfall intermittency and the sampling error of tipping-bucket rain gauges

This work amplifies upon the influence of rainfall intermittency on pluviom etric time series. Intermittency is here defined as the percentage of no-ra in periods within a rainfall event, and can be interpreted as a sort of-sto chastic intermittency', When measuring an intermittent or, in general, 'err atic' signal, a relevant source of error is associated with the sampling pr ocedure. By using numerical simulation of intermittent rainfall events, we focus on the deriving pattern of sampling errors within rainfall measuremen ts obtained from any classic tipping-bucket rain gauge. The analysis, perfo rmed in both the time and frequency domain, reveals a strong inverse linear dependence between rainfall intermittency and the sampling errors, while a weak dependence on the autocorrelation of synthetic rainfall events is sho wn. The average absolute error is around 30% for the events analysed while the error at each sampling period peaks values higher than 100%. A direct i nfluence of intermittency on the statistical characteristics of measured ra infall events is observed, (C) 2001 Elsevier Science Ltd. All rights reserv ed.