Commercial microwave links instead of rain gauges: fiction or reality?

Abstract

Commercial microwave links (MWLs) were suggested about a decade ago as a new source for quantitative precipitation estimates (QPEs). Meanwhile, the theory is well understood and rainfall monitoring with MWLs is on its way to being a mature technology, with several well-documented case studies, which investigate QPEs from multiple MWLs on the mesoscale. However, the potential of MWLs to observe microscale rainfall variability, which is important for urban hydrology, has not been investigated yet. In this paper, we assess the potential of MWLs to capture the spatio-temporal rainfall dynamics over small catchments of a few square kilometres. Specifically, we investigate the influence of different MWL topologies on areal rainfall estimation, which is important for experimental design or to a priori check the feasibility of using MWLs. In a dedicated case study in Prague, Czech Republic, we collected a unique dataset of 14 MWL signals with a temporal resolution of a few seconds and compared the QPEs from the MWLs to reference rainfall from multiple rain gauges. Our results show that, although QPEs from most MWLs are probably positively biased, they capture spatio-temporal rainfall variability on the microscale very well. Thus, they have great potential to improve runoff predictions. This is especially beneficial for heavy rainfall, which is usually decisive for urban drainage design.

Spatial and temporal variability of rainfall and their effects on hydrological response in urban areas – a review

“…More recently, commercial microwave links have been used to estimate the spatial and temporal rainfall variability (Leijnse et al, 2007;Fencl et al, 2015Fencl et al, , 2017. Rainfall estimates are obtained from the attenuation of the signal caused by rain along microwave link paths.…”

Rainfall Detection and Rainfall Rate Estimation Using Microwave Attenuation

“…This is consistent with the findings of Schleiss and Berne [16], who suggested that varying W t according to the rainfall pattern improves the accuracy of the rainfall detection rates under clear sky and rainy conditions. Fencl et al [25] applied a W t of 60 min (before rainfall) and 180 min (after rainfall) to eliminate the potential influence of attenuation by antenna wetting. Leijnse et al [33] showed that the effect of the shift in the A clear is seen to be major, especially for a long-lasting and low-intensity event.…”

“…Rainfall intensity distributions were then reconstructed from seven cellular microwave links that have lengths of 1-17 km and operate at frequencies of 8-23 GHz [12]. Fencl et al [25] investigate the effects of different topologies of microwave link networks on the retrieved spatio-temporal rainfall dynamics over an urban catchment and reported that most microwave links capture microscale rainfall variability very well. Barthès and Mallet [26] used Ku-band microwave sources on geostationary satellites to estimate rainfall.…”

Real-time data acquisition of commercial microwave link networks for hydrometeorological applications

“…Just recently, Fencl et al (2015) have mentioned a similar approach, also using a custom data acquisition software running within an operational CML network. In contrast to the software that we are presenting here, which handles multiple parallel requests of CML data, their software is only capable of serial data acquisition.…”