The Next Generation Airborne Polarimetric Doppler Weather Radar

Understanding climate processes and high impact weather has become one of the top scientific challenges for the atmospheric scientific community. This concern led to extensive research focused on the evolution of kinematic and microphysical structures in storms often located in remote regions over land and/or ocean. One of the key mobile instruments used to sample these systems is airborne Doppler radar to obtain concurrently high temporal and spatial resolution measurements of 3-D winds. At present, airborne tail weather radars were mechanical scanning along the axis of the fuselage. The slotted waveguide antennas are not designed and cannot be modified for collecting dual-polarization measurements to remotely measure microphysical characteristics.

Recently, ground-based phased array radar (PAR) demonstrated the high time resolution estimation of accurate Doppler velocity and reflectivity of precipitation and clouds when compared to conventional, mechanically scanning radars. PAR uses electronic scanning (e-scan) to rapidly collect radar measurements which is critical for airborne applications. More importantly, PAR enables the dual-polarization capability not currently available in airborne tail Doppler radars. Hence, a PAR mounted on an airborne platform with dual-polarization capability has the potential for significantly advancing the science of understanding climate processes and high impact weather. This paper presents the proposed configuration of a novel Airborne Phased Array Radar (APAR) to be developed at the NCAR Earth Observing Laboratory and installed on the NSF/NCAR C-130 aircraft. The proposed APAR would replace the aging, X-band Electra Doppler radar (ELDORA). Dual polarization and operation at C-Band improves APAR's ability to penetrate into heavy precipitation to observe both dynamical and microphysical properties in storms. The system design takes advantage of the tremendous improvements in RF and digital miniaturized technologies and advanced beam forming, data processing and display capabilities. This APAR design can be duplicated for other C-130 aircraft (e.g., US Air Force Hurricane Hunters) and enhance both the climate and weather research in addition to monitoring high impact weather.