Accurate measurements of rainfall are important in many hydrological andmeteorological applications, for instance, flash-flood early-warning systems,hydraulic structures design, irrigation, weather forecasting, and climatemodelling. Whenever possible, link networks measure and store the receivedpower of the electromagnetic signal at regular intervals. The decrease inpower can be converted to rainfall intensity, and is largely due to theattenuation by raindrops along the link paths. Such an alternative techniquefulfils the continuous effort to obtain measurements of rainfall in time and spaceat higher resolutions, especially in places where traditional rain gaugenetworks are scarce or poorly maintained.Rainfall maps from microwave link networks have recently been introduced atcountry-wide scales. Despite their potential in rainfall estimation at highspatiotemporal resolutions, the uncertainties present in rainfall maps fromlink networks are not yet fully comprehended. The aim of this work is toidentify and quantify the sources of uncertainty present in interpolatedrainfall maps from link rainfall depths. In order to disentangle thesesources of uncertainty, we classified them into two categories: (1) thoseassociated with the individual microwave link measurements, i.e. the errorsinvolved in link rainfall retrievals, such as wetantenna attenuation, sampling interval of measurements, wet/dry periodclassification, dry weather baseline attenuation, quantization of thereceived power, drop size distribution (DSD), and multi-path propagation; and(2) those associated with mapping, i.e. the combined effect of theinterpolation methodology and the spatial density of link measurements.We computed ~ 3500 rainfall maps from real and simulated link rainfalldepths for 12 days for the land surface of the Netherlands. Simulated linkrainfall depths refer to path-averaged rainfall depths obtained from radardata. The ~ 3500 real and simulated rainfall maps were compared againstquality-controlled gauge-adjusted radar rainfall fields (assumed to be theground truth). Thus, we were able to not only identify and quantify thesources of uncertainty in such rainfall maps, but also test the actual andoptimal performance of one commercial microwave network from one of thecellular providers in the Netherlands. Errors in microwave link measurementswere found to be the source that contributes most to the overall uncertainty.
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