Space-time modeling of a rainfall field ; Application to daily rainfall in the Loire basin

From raingauge data, it is possible to mathematically model rainfall field as a spatio-temporal intermittent process (superposition of inner variability field and rainfall indicator field, both influenced by advection). Geostatistics enables investigation of the link between an instantaneous process spatio-temporal structure and the evolution of spatial structure with time aggregation. A method is proposed to infer a relevant instantaneous process from observed rainfall statistics. The benefits and limits of this approach are investigated using daily rainfall data from the Loire basin in France. Two sub-regions are highlighted. A downstream zone where a quite homogeneous rainfall process can be modelled by the spatio-temporal model, and an upstream zone where interaction with orography is more present and the homogenity assumption questionable.