Adaptive Tracking of Thunderstorm Cells at X-band

The Swiss Meteorological Service MeteoSwiss operates besides the polarimetric C-band weather radar network also a mobile polarimetric X-band weather radar. Since many years an operational thunderstorm radar tracking (TRT) algorithm is implemented based on the data of the C-band network. The TRT identifies thunderstorm cells, classifies them by their severity, and estimates their further propagation. In order to get a deep insight into thunderstorm dynamics and microphysics, the TRT algorithm was combined with the X-band radar: whenever a thunderstorm cell that is identified by the TRT enters the measurement domain of the X-band system, then the X-band radar automatically executes RHI scans in the direction of the core of the thunderstorm cell. This cell is then tracked until it leaves the measurement domain if the cell is not decaying before. In summer 2015, the X-band radar will be deployed in the most hail-prone region of Switzerland, where also a couple of newly developed hail sensors are being installed. This set-up allows the detailed observation of hail-bearing thunderstorms during their full life cycle with unprecedented spatial and temporal resolution combined with unique ground-truth data. Due to the fact that observations are acquired in spectal mode, the polarimetric moments of the X-band radar are available as a function of the Doppler velocity, which allows an even deeper insight into the dynamics of the thunderstorm. Up to now a series of cells were tracked and we are going to present the first analysis in view of the microphysics related to the lifecycle of these systems. We expect that these measurements lead to a deeper understanding of hail formation in thunderstorm clouds.