Proposition of an Index for the Study of the Variability of Space-Temporal Rainfall in Brazil

Abstract Brazil shows a high spatial and temporal pluviometric variability. Therefore, it is crucial to systematically represent this phenomena in order to know the influence of precipitation for the hydrological cycle and several human activities. Thus, it is proposed a metrics called IPE (Index of Scale Proportion) to assess the relative contribution of the time and space on the rainfall variability, aiming to identify multi-scalar climatic patterns and to relate them to the main meteorological driver systems. We used data from 809 locations and identified five main patterns for IPE in distinct spatiotemporal configuration. The patterns called A, B and C describe a range of low IPE values (major importance of space relative to time) covering a large circular area with its limits near to the country edge. The patterns called D and E are located respectively on central and south area of country, showing high IPE values (time factor was relatively more important). It was possible to correlate the described IPE patterns to the well-know weather systems, gathering a preliminary characterization that help us to clarify the spatiotemporal rainfall variability.