Identifying the scaling properties of rainfall accumulation as measured by a rain gauge network

Recent studies have revealed that rainfall has non-trivial structure on small (less than 1 km) and short (less than 5 min) spatio-temporal scales. Despite this realization, instruments with substantially poorer resolution are still often used to characterize rainfall accumulations and other rain microphysical parameters such as mean drop diameter, radar reflectivity, and drop size distribution. There are many recent investigations that have supplied evidence that rainfall may have scale-invariant properties. If this is true, instruments with course resolution should only be trusted to estimate microphysical properties in a spatio-temporal regime where they are able to resolve the scale-invariant nature of the data. Here, we use a small-scale tipping-bucket rain gauge network (an instrument with inherent temporal scale limitations) to identify the minimum and maximum time scales over which a storm's scale-invariant behavior can be resolved. This gives some insight to the minimum time scale of scientific value from this instrument and the technique utilized here can be extended to a variety of other scale-limited raindrop measurement instruments (e.g. Joss-Waldvogel disdrometers, weighing rain gauges, or radar). (C) 2010 Elsevier B.V. All rights reserved.