Seasonal semi-variance of Dutch rainfall at hourly to daily scales

Using 30. years (1979-2009) of data from 33 automatic rain gauges in the Netherlands, a study of the space-time variability of rainfall is performed. This study uses 90-day averaged semi-variograms to find seasonal signals in the fitted spherical semi-variogram parameters of rainrates in the Netherlands, for accumulation intervals between 1 and 24. h. These signals can be well-described by simple cosine functions. The dependence of these cosine functions on the accumulation interval is modeled in two different ways: (1) power-law relations between the variogram parameters and the accumulation interval, and (2) power-law relations between the parameters of the cosine functions and the accumulation interval. For the first method the cosine function at the 24-h accumulation interval is also needed. The second of these methods has more parameters, but is shown to model the temporal scaling best. The space-time scaling relations found in this paper are compared to those found by others for similar and contrasting climates. Seasonality is shown to play an important role in determining rainfall spatial variability.