THE ELDORA ASTRAIA AIRBORNE DOPPLER WEATHER RADAR - HIGH-RESOLUTION OBSERVATIONS FROM TOGA COARE/

The ELDORA/ASTRAIA (Electra Doppler Radar/Analyese Stereoscopic par Im pulsions Aeroporte) airborne Doppler weather radar was recently placed in service by the National Center for Atmospheric Research and the Ce ntre d'etude des Environnements Terrestre et Planetaires in France. Af ter a multiyear development effort, the radar saw its first field test s in the TOGA COARE (Tropical Oceans-Global Atmosphere Coupled Ocean-A tmosphere Response Experiment) field program during January and Februa ry 1993. The ELDORA/ASTRAIA radar (herein referred to as ELDORA) is de signed to provide high-resolution measurements of the air motion and r ainfall characteristics of very large storms, storms that are frequent ly too large or too remote to be adequately observed by ground-based r adars. This paper discusses the measurement requirements and the desig n goals of the radar and concludes with an evaluation of the performan ce of the system using data from TOGA COARE. The performance evaluatio n includes data from two cases. First, observations of a mesoscale con vective system on 9 February 1993 are used to compare the data quality of the ELDORA radar with the National Oceanic and Atmospheric Adminis tration P-3 airborne Doppler radars. The large-scale storm structure a nd airflow from ELDORA are seen to compare quite well with analyses us ing data from the P-3 radars. The major differences observed between t he ELDORA and P-3 radar analyses were due to the higher resolution of the ELDORA data and due to the different domains observed by the indiv idual radars, a result of the selection of flight track past the storm for each aircraft. In a second example, the high-resolution capabilit ies of ELDORA are evaluated using observations of a shear-parallel mes oscale convective system (MCS) that occurred on 18 February 1993. This MCS line was characterized by shear-parallel clusters of small convec tive cells, clusters that were moving quickly with the low-level winds . High-resolution analysis of these data provided a clear picture of t he small scale of the storm vertical velocity structure associated wit h individual convective cells. The peak vertical velocities measured i n the high-resolution analysis were also increased above low-resolutio n analysis values, in many areas by 50%-100%. This case exemplifies th e need for high-resolution measurement and analysis of convective tran sport, even if the goal is to measure and parameterize the large-scale effects of storms. The paper concludes with a discussion of completio n of the remaining ELDORA design goals and planned near-term upgrades to the system. These upgrades include an implementation of dual-pulse repetition frequency and development of real-time, in-flight dual-Dopp ler analysis capability.