Airborne Doppler Radar Analysis of Supercells during COPS-91

Abstract

On 26 May 1991, NOAA P-3 airborne Doppler radar data were collected near two tornadic supercells in the southern Plains during the Cooperative Oklahoma Profiler Studies (COPS-91) field program. The 3-cm radar mounted in the tail of the aircraft was operated using the fore?aft scanning technique (FAST). Both storms were sampled just minutes after each had produced a tornado. The COPS-91 storms are the first tornadic supercells to be sampled extensively by airborne Doppler radar using the FAST methodology. Pseudo-dual-Doppler analyses of a dissipating storm in southwest Kansas show no remaining low-level circulation, even though the storm had just produced a tornado. The analyses of a storm in northwest Oklahoma reveal better-defined features in the wind field near the surface. In contrast to what has been previously observed in post-tornadic supercells, the cyclonic vorticity in both storms was greater aloft than at low levels. The 26 May 1991 storms provide further evidence that supercells often contain multiple updrafts and mesocyclones. Cyclical mesocyclogenesis was occurring in the northwest Oklahoma storm while pseudo-dual-Doppler data were being collected. Airborne Doppler radar provides the potential for obtaining datasets throughout the lifetime of a storm at close range, where the observational geometry can be controlled to minimize known errors. The lessons learned from COPS-91 were incorporated into the airborne Doppler strategies employed during the subsequent Verificafion of the Origins of Rotation in Tornadoes Experiment (1994?95).