In 2019, the GSMA AgriTech programme, together with Wageningen University and the Royal Netherlands Meteorological Institute, piloted with Dialog Sri Lanka the use of Commercial Microwave Links (CMLs) for rainfall monitoring.

CMLs are radio connections used in mobile networks. During rainfall, water absorbs and scatters microwave signals resulting in subtle changes to the signal strength. CML data can be analysed and converted into highly accurate rainfall measurements, turning the mobile network into a network of virtual-sensing rain gauges.

The experience of Dialog Sri Lanka shows that the use of CML data for rainfall monitoring can address the data gap in rainfall measurements. It also presents an opportunity to strengthen the climate resilience of rural populations by improving key services such as weather forecasts, weather insurance and data-driven agriculture.