NCAR/EOL Airborne Phased Array Radar (APAR): Recent Progress and Future Development Efforts

The NCAR Earth Observing Laboratory (EOL) is currently undertaking preliminary system design studies, engineering prototype testing and project management plan preparation for the development of a novel Airborne Phased Array Radar (APAR). The system being designed by NCAR/EOL will be installed and operated 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 ~3000 active radiating elements arranged in an array of Line Replaceable Units (LRU) to simplify maintenance. APAR will provide unprecedented observations, and in conjunction with advanced radar data assimilation schemes and high-resolution numerical modeling, will be able to address the key science questions needed to improve understanding and predictability high-impact weather events.

The present talk will briefly describe the APAR program as well as the development activities over the past year. These activities include the testing and calibration of a 16-element antenna array and the finalization of the APAR Project Management Plan. However, the primary focus of this talk will be on the near term system development underway. EOL has recently identified four key risk reduction activities that will refine the APAR system design and cost and schedule estimates.

These specific activities include: i) the APAR AESA Trade Studies. Industry partners will conduct the trade studies and the results will allow the APAR Project Team to evaluate several different technical solutions, alternate performance thresholds, and other engineering considerations that will serve as input to the final design of APAR. ii) Completion of the 64-element Phased Array Radar (PAR) LRU Demonstrator. The design and implementation of the LRU Demonstrator will allow EOL to develop and test several important elements of the final APAR system from both a hardware and software perspective. Integrating these elements into a single system should uncover any potential issues with the current APAR design. iii) Vibration testing on the NSF/NCAR C-130. The vibration testing will occur in two stages. Modal testing on the ground will be conducted to obtain experimental data of the whole aircraft. Flight-testing will then be accomplished to provide higher frequency data for verification of APAR performance and provide data on vibration characteristics and dynamic response of the system. iv) Finally, an APAR Observation Simulator (AOS) Prototype will permit model generated APAR reflectivity and Doppler velocity observations from idealized numerical simulations of high-impact weather events. The results of the simulations will allow EOL to evaluate and optimize APAR scanning strategies, and develop sampling requirements for deriving useful radar variables

A complete description of these activities and a discussion on how they fit into the overall APAR project will be presented.