An Illustration of Non-Conventional Scanning Strategies by NSSL’s Advanced Technology Demonstrator Phased Array Radar

In 2024, the National Severe Storms Laboratory (NSSL) operated the dual-polarization Advanced Technology Demonstrator (ATD) phased array radar (PAR) in a wide variety of severe weather events. PAR is one technology that is being considered as an option to replace the current United States’ Weather Surveillance Radar - 1988 Doppler (WSR-88D) systems, which are nearing their end of life. Most weather operational radars collect data in plan position indicator (PPI) mode in order to capture the three-dimensional structures of weather echoes. Likewise, they leverage simultaneous transmit and simultaneous receive (STSR) to retrieve dual-polarization information. Collecting data in non-conventional range height indicator (RHI) mode or single-polarization transmission and simultaneous receive mode to retrieve Linear Depolarization Ratio (LDR), for example, adds time to scanning strategies and is rarely, if ever, employed by mechanically driven operational weather radars.

Since PAR can quickly point the radar beam without the use of mechanical steering, non-conventional scanning strategies beyond typical STSR PPIs can be employed to more completely observe the atmosphere with minimal temporal delay. In 2024, the ability to collect data in LDR mode was implemented on the ATD for a more detailed examination of hydrometeor size and orientation. Likewise, RHIs (LDR or STSR) were collected to quickly capture the vertical structure of severe convection. Thus, the ATD often operated by collecting conventional STSR PPI volumes followed by non-conventional STSR RHIs, LDR RHIs, and/or a single LDR PPI at the lowest elevation scan. In this presentation, we will show observations from several cases including: 1) STSR RHIs in a severe multicell cluster on 6–7 May 2024, 2) LDR PPIs in a hail-producing supercell on 25–26 May 2024, and 3) LDR RHIs through a tornado- and hail-producing supercell on 19–20 May 2024. The design of the ATD scanning strategies and potential implications for future operational use will be discussed. Peripheral takeaways from participants who briefly examined some ATD-based non-conventional scanning strategies in the August 2024 Hazardous Weather Testbed dual-polarization PAR activity will be briefly described.