Supervision : Dominique BÉRÉZIAT

Co-supervision : HERLIN Isabelle (INRIA)

Estimation of dynamics from multiscale image assimilation. Application to : Rain nowcasting from ground radar images

The forecast of precipitation takes a special place, in view of their direct economic impact. These forecasts allow, on the one hand, to anticipate environmental constraints and optimise, for example, the management of water resources, and, on the other hand, to anticipate flood risks.
The aim of this study is to improve the nowcasting of precipitation rate of the Rain Nowcast (RN) algorithm that previously provides relevant forecasts for a time horizon of 30 minutes. A multi-scale approach is suggested to merge two types of radar data, with different spatial resolutions, in order to increase the time horizon of the forecast while ensuring a forecast of quality in terms of both location and quantity of precipitation.
We propose two multi-scales algorithms, the first one is sequential "Sequential Motion RN" : a global estimation with regional data to guide a local estimation with local data. The second is parallel "Parallel Motion RN": using both local and regional data simultaneously. Two other methods dedicated to forecast have been proposed: geostrophic wind hypothesis, which involves correcting the underestimation motion intensity for low contrast structures in radar images. The second method: histogram correction, which involves correcting the smoothing effect caused by the numerical scheme by using a widely described technique in literature, to correct raingauge measurements estimated from radar images.

2018-2020 Publications

• 2020
  • A. Zebiri : “Estimation de la dynamique à partir de l’assimilation d’images radars multi-échelles. Application à la prévision a court terme de taux de précipitation à partir des images radars”, thesis, phd defence 06/11/2020, supervision Béréziat, Dominique, co-supervision : Herlin, Isabelle (INRIA) (2020)
• 2019
  • A. Zébiri, D. Béréziat, E. Huot, I. Herlin, E. Buisson : “Prévision multi-échelles des précipitations”, GRETSI 2019 - XXVIIème Colloque francophone de traitement du signal et des images, Lille, France, pp. 4 p. (2019)
  • A. Zébiri, D. Béréziat, E. Huot, I. Herlin : “Rain Nowcasting from Multiscale Radar Images”, VISAPP 2019 - 14^th International Conference on Computer Vision Theory and Applications, Prague, Czechia, pp. 1-9 (2019)
• 2018
  • E. Huot, D. Béréziat, A. Zébiri : “Prévision de la pluie à court terme par assimilation d’images radar”, Colloque scientifique international «Observation et prévision des pluies, impacts sur les crues», Tunis, Tunisia (2018)