Polarimetric Weather Observations with the Fully Digital Horus Radar

Phased Array Radar (PAR) technology offers advanced capabilities that could support the enhanced weather surveillance strategies envisioned to improve the update time and quality of weather radar observations (Zrnić et al., 2007, Palmer et al., 2022). Dual-polarization technology provides measurements through transmission and reception of electromagnetic waves in both Horizontal (H) and Vertical (V) polarizations, often in simultaneous transmit / simultaneous receive (STSR) or alternating transmit / simultaneous receive (ATSR) modes. Subsequently, these measurements are used to estimate spectral moments and polarimetric variables (Ryzhkov and Zrnić 2019). These polarimetric variables provide mission-critical information about the type, size, and quantity of scatterers in the radar resolution volume. However, precise measurements of polarimetric variables are difficult to achieve because radiation patterns of phased array antennas have inherent dependence of their polarization, shape, and gain on the steering direction. Therefore, advanced digital PARs are being developed to mitigate antenna-induced biases using a combination of hardware design and array calibration techniques.

The Advanced Radar Research Center (ARRC) at the University of Oklahoma (OU) has developed a digital-at-every-element, S-band, dual-polarization phased array radar named “Horus”. The Horus radar started making meteorological observations in 2022 (Palmer et al., 2023). Data collection experiments are routinely being conducted, and the quality of polarimetric weather observations is being analyzed. With current efforts focused on evaluating the digital, rotating PAR technology as a potential radar for nationwide polarimetric weather surveillance, quantitative evaluation of polarimetric weather data from Horus is critical to inform future decision making. This paper presents recent field observations with Horus, along with an evaluation of its polarimetric data quality.

References

• Zrnić, D. S., and Coauthors, 2007: Agile-Beam Phased Array Radar for Weather Observations. Amer. Meteor. Soc., 88, 1753–1766.
• Palmer, R., and Coauthors, 2022: A Primer on Phased Array Radar Technology for the Atmospheric Sciences. Amer. Meteor. Soc., 103, E2391–E2416.
• Ryzhkov, Alexander V., and Dušan S. Zrnić. Radar polarimetry for weather observations. Vol. 486. Cham, Switzerland: Springer International Publishing, 2019.
• Palmer, and Coauthors, 2023. “Horus – A Fully Digital Polarimetric Phased Array Radar for Next-Generation Weather Observations.” IEEE Transactions on Radar Systems. Submitted.