According to these maps, the majority of the land surface of the Earth lacks surface precipitation measurements, and in many parts of the world, the density of surface precipitation gauging networks is even rapidly declining. This development can potentially be counteracted by using received signal level data from the enormous number of microwave links used worldwide in commercial cellular communication networks. Rain-induced attenuation and, subsequently, path-averaged rainfall intensity can be retrieved from the signal"s attenuation between transmitter and receiver.