Airborne Phased Array Radar (APAR): The Next Generation of Airborne Polarimetric Doppler Weather Radar

This paper presents a possible configuration of a novel, airborne phased array radar motivated by major advances in cellular technology, component miniaturization, and radar antenna simulation software. This has paved the way for a next-generation radar being designed by NCAR/EOL to be installed on the NSF/NCAR C-130 aircraft. The APAR system will consist of four removable C-band active electronically scanned arrays (AESA) strategically placed on the fuselage of the aircraft. Each AESA measures approximately 1.5 x 1.9 m and is composed of 3584 active radiating elements arranged in a rectangular array of 7 x 8 line replaceable units (LRU). Each LRU is composed of 64 radiating elements that are the building block of the APAR system.

APAR, at C-band, allows the measurement of 3-D kinematics of the inner core and rainband structures with less attenuation compared with current airborne Doppler radar systems. The unique combination of APAR capabilities as well as water vapor measurements using dropsonde and in situ measurements, and other remote sensing instruments such as cloud radar and wind lidar from a single airborne platform, will help scientists to examine the role of the hurricane eye with regard to intensity changes. The combination of measurements from dropsondes, in situ probes and Doppler radar will allow unprecedented investigations into the optimization of observing strategies and data assimilation research for improving the predictions of the track, intensity and structure of tropical and extra tropical cyclones.

Polarimetric measurements are not available from current airborne tail Doppler radars. However, APAR, with dual-Doppler and dual polarization diversity at a lesser attenuating C-band wavelength, will further advance the understanding of the microphysical processes within a variety of precipitation systems. Such unprecedented observations, in conjunction with the advanced radar data assimilation schema, will be able to address the key science questions to improve understanding and predictability of significant weather.

The development now underway is expected to take ~7 more years. It adopts a phased approach as an active risk assessment and mitigation strategy. The APAR Team is actively seeking partners in industry and in the university community. An APAR science and engineering advisory panel has been organized. The authors will review the overall design and current progress of APAR and outline ambitious future development work needed to bring this exceptional tool into full operation.