Spatial variability of daily summer rainfall at a local-scale in a mountainous terrain and humid tropical region

The authors study the spatial variability of daily rainfall in a mountainous terrain and tropical humid region within a grid of 6 km × 6 km using daily rainfall data from 22 non-recording rain gauges over a period of 39 days. Results indicate that (1) the daily coefficient of variation varied from 15% to 53%, and (2) among all, five of the rain gauge locations consistently gave estimates of the spatial daily mean rainfall within root mean square error of 20%, ten locations gave estimates with root mean square errors ranging from 20% to 30%, and the remaining seven locations gave estimates with root mean square error ranging from 30% to 41%. These levels of errors must be acknowledged when using single rain gauges to estimate local-scale spatial means at the daily scale. This also indicates that there are temporally stable rain gauge locations that give consistently lower errors in spatial mean estimates. Such short-term field campaigns can be used to identify time stable rain gauge locations for rain gauge network design.