Real-time multiple-Doppler wind fields from RHYTMME and ARAMIS radars with implications for data assimilation within AROME for southeast France

With elevations ranging from sea level to more than 2500 m ASL in the Southern Alps, southeastern France is prone to orographically-induced flooding and other rapidly-developing mesoscale dynamics. In an effort to improve the understanding of these events, the installation of new polarimetric X-band radars, within the scope of the RHYTMME project, has resulted in a dense array of radar coverage over southeast France. Coupled with pre-existing, polarimetric S- and C-band radars from the national ARAMIS network, the opportunity exists for dual- and over-determined Doppler wind field analyses on a near real-time basis. These 3D wind field data can then be used for verification of the AROME model and eventually for data assimilation. At present, only radial velocities from ARAMIS radars are initialized within AROME.

Therefore, the objective of this work is to first accurately implement real-time, multiple-Doppler wind field syntheses over southeast France. This process is aided by the ability to use polarimetric moments to filter and edit real-time velocity data automatically. The next step of this research will involve comparison of AROME model output, with and without radial velocity assimilation, to multiple-Doppler synthesized wind fields. Finally, assimilation of these 3D wind field syntheses into AROME will be conducted, with the aim of improving the accuracy of mesoscale simulations.