C-Band Dual-Doppler Retrievals in Complex Terrain: Improving the Knowledge of Severe Storm Dynamics in Catalonia

Abstract

Convective activity in Catalonia (northeastern Spain) mainly occurs during summer and autumn, with severe weather occurring 33 days per year on average. In some cases, the storms have unexpected propagation characteristics, likely due to a combination of the complex topography and the thunderstorms’ propagation mechanisms. Partly due to the local nature of the events, numerical weather prediction models are not able to accurately nowcast the complex mesoscale mechanisms (i.e., local influence of topography). This directly impacts the retrieved position and motion of the storms, and consequently, the likely associated storm severity. Although a successful warning system based on lightning and radar observations has been developed, there remains a lack of knowledge of storm dynamics that could lead to forecast improvements. The present study explores the capabilities of the radar network at the Meteorological Service of Catalonia to retrieve dual-Doppler wind fields to study the dynamics of Catalan thunderstorms. A severe thunderstorm that splits and a tornado-producing supercell that is channeled through a valley are used to demonstrate the capabilities of an advanced open source technique that retrieves dynamical variables from C-band operational radars in complex terrain. For the first time in the Iberian Peninsula, complete 3D storm-relative winds are obtained, providing information about the internal dynamics of the storms. This aids in the analyses of the interaction between different storm cells within a system and/or the interaction of the cells with the local topography.

The Results of Applying Different Methodologies to 10 Years of Quantitative Precipitation Estimation in Catalonia Using Weather Radar

“…Because of its topography and location (proximity to the Mediterranean Sea), the region is regularly affected by convective activity that causes severe weather and intense rainfall [18]. This geographical configuration also plays an important role in the fact that numerical weather prediction models have great difficulties in reproducing convective episodes at the scale of thunderstorms [19]. Because of this, using weather radar (XRAD) and rain gauges (XEMA) from automatic weather stations (AWS), the networks provide the results that are strictly necessary for surveillance tasks in the region.…”

“…Except for some specific differences (regarding specific geographic issues: height of the system or proximity to the sea, which is a defining factor in the anomalous propagation of the beam [24]), all the radars in the XRAD network have similar performances including hardware, software, mechanics, electronics, and the programmed elevations. Corrections in this case are based on a series of filters that consider different relationships between quality control parameters depending on the radar variables (more information about the filter process can be found in [14,19]). The final reflectivity field products (COR 1 in Figure 2) only remove topographic echoes, but many other non-meteorological echoes remain uncorrected (electromagnetic interferences, bright band effect, beam blockage, wind farms, etc.).…”

Observational Analysis of a Wind Gust Event during the Merging of a Bow Echo and Mini-Supercell in Southeastern China

“…Doppler radars have played a vital role in nowcasting severe weather events and monitoring the evolutionary characteristics of convective structures [35]. In addition, the usage of dual polarization data provides more information for severe weather analysis.…”