Climatological Identification of the Non-Stationarities of Intermittent Precipitation Fields

Abstract

In many geophysical sciences, precipitation appears as a key variable. In hydrology, it forms the input of rainfall-runoff models used for flood forecasting or the management of hydroelectric dams. In meteorological or climatological models, its knowledge is necessary on meshes of 30×30 to 100×100 Km². Its evolution through the soil and the vegetation determines the mass and heat exchanges between the biosphere and the atmosphere and, consequently the evolution of weather and climates. Therefore, it is necessary to have powerful tools for the interpolation of rainfall fields, or the estimation of mean areal rainfall. However, when the timestep considered decreases (a few hours to a few minutes), the intermittency phenomenon appears and precipitation is thus highly non stationary. Non-stationarities are also present in rainfall cells themselves. Indeed, the physical study of rainfall generation shows that lower intensities than in the center are encountered at the edge of the cells. Prior to any kriging or interpolation, it would be of interest to remove this first order non-stationarity.