“…For high-resolution rainfall mapping in urban areas on the other hand, where microwave link networks are much denser than those in rural areas and, as a consequence, propagation paths may cross each other, the mapping problem is essentially a tomographic problem rather than an interpolation problem. Techniques to tackle this challenging problem (i.e., rainfall mapping on a spatial grid that is finer than the average link length) have been proposed in the scientific literature, typically taking advantage of the sparsity of the rainfall phenomenon (Giuli et al, 1991;Roy, Gishkori, & Leus, 2016). Since the appearance of microwave link networks changes over time, the quality of rainfall maps, either based on (geostatistical) interpolation (Goldshtein, Messer, & Zinevich, 2009;Overeem et al, 2016a), on tomography (Zinevich, Alpert, & Messer, 2008), or on a form of data assimilation (Bianchi, van Leeuwen, Hogan, & Berne, 2013;Zinevich, Messer, & Alpert, 2009) will also be time-dependent.…”