EXTENDED OVERDETERMINED DUAL-DOPPLER FORMALISM IN SYNTHESIZING AIRBORNE DOPPLER RADAR DATA

During the intensive observing period of the held phase of the Coupled Ocean-Atmosphere Response Experiment (COARE) of the Tropical Oceans a nd Global Atmosphere (TOGA) program, airborne Doppler radars capable o f fore-aft scanning (dual-Doppler analog) were involved in aircraft mi ssions in which highly coordinated and parallel tracks were flown (qua d-Doppler analog). Pairs of observations from each radar can be used t o infer the wind components through an iterative dual-equation solutio n, while combining them allows a direct determination. Errors from the se two analysis methods are discussed, in particular those induced fro m geometrical considerations. Due to these geometrical limitations, ne ither the dual-Doppler nor the quad-Doppler approach can take advantag e of the whole volume sampling. To overcome the limitations and to inc rease considerably the synthesis domain, the overdetermined dual-Doppl er (ODD) technique is proposed in an extended version (EODD). EODD inc ludes solutions to these problems as well as means to mitigate the ine vitable contribution of errors in estimating the vertical velocity, pr eviously described In early studies. The EODD technique is applied to data collected in a squall line that occurred near Guadalcanal Island on 22 February 1993, from Doppler radars aboard the two NOAA WP-3D air craft. Similar airflow structures, consistent with those from previous studies, are obtained from application of the EODD method to dual-Dop pler and quad-Doppler observations, indicative of the validity of usin g the proposed method to solve either dual- or quad-Doppler data confi gurations.