Operational phased array radar network for natural hazard monitoring and warnings in urban environments over the Greater Bay Area, China

The continuous development of modern Doppler weather radars has substantially augmented our capacity to monitor severe convective storms and gain insights into their dynamic and microphysical structures. Although conventional parabolic antenna-based S-band operational radars are valuable, they exhibit limitations such as low scanning speed and reduced information acquisition in the low atmosphere region, particularly at far ranges from the radar, leading to suboptimal observations of fast-evolving storms. To address these limitations, a dense X-band polarimetric phased array radar (PAR) network, consisting of more than 50 radars, has been strategically constructed and deployed in the Greater Bay Area in South China, which is currently the largest PAR network worldwide. The PARs exhibit satisfactory performance in hydrometeor classification, hail identification, and quantitative precipitation estimation, demonstrating reliable polarimetric data quality. The paper also presents compelling evidence demonstrating the effectiveness of the PAR network in detecting the tornado vortex and capturing fine horizontal and vertical structures of convective storms when compared to nearby S-band operational radars. In addition, the assimilation of supplemental PAR data using the ensemble Kalman filter has yielded discernible vortex circulation fields for tornadic storms, enabling effective prediction of tornadogenesis, which is unattainable solely by assimilating S-band operational radar data. As the PAR network is put into operational use, significant advancements are anticipated in understanding and monitoring severe weather systems in South China.