A multifractal approach to handle rainfall and wind’s extreme variability, and examples of associated applications
Rainfall and wind are known to exhibit extreme variability over a wide range of spatio-temporal scales. Such features make these fields complex to analyse, model and even to measure. Universal Multifractals are a common tool to address such features. They rely on the physically based notion of scale invariance, which is inherited from Navier-Stokes equations. In this framework, geophysical fields are generated by an underlying multiplicative cascade process characterized with the help of only 3 parameters with physical interpretation.
In this presentation, I will start by highlighting the main features of Universal Multifractals framework. Then I will present a blunt extension of discrete cascades which enables to overcome the well known non translation invariance issue of standard cascade while preserving the simple structure of discrete cascades. Finally two examples of applications requiring combined analysis of wind and rainfall features across scales will be discussed (i) 3D trajectories of falling rainfall drops and (ii) influence of rainfall on wind power production. The latter being studied in the framwork of the ANR JCJC RW-Turb project, whose main outcomes will be introduced.
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