On December 12 1992, during TOGA-COARE (Tropical Ocean Global Atmosphere - Coupled Ocean-Atmosphere Response Experiment), enhanced convection was observed in the northeast of the COARE Intensive Flux Array (IFA: 1ºN-4ºS, 151-158ºE), occurring in a broad cyclonic flow at low levels and divergent northeasterly flow at upper levels. Satellite IR (Infra Red) pictures revealed scattered Class 2/3 convection, and indicated a discrete propagation toward southwest. Radar observations from two NOAA WP-3D aircrafts showed moderated convective cells, located in a stratiform precipitation region, and stronger convective cells in the southwest part of the system. During the two-plane mission, several "quad-Doppler" observations were obtained from the four-pattern legs described by each aircraft, first along the convective line and after in the stratiform part of the system. Combination of parallel portions of these aircraft flight tracks was made to synthesize the 3D wind fields, using the Extended Overdetermined Dual-Doppler technique (EODD). These radar-derived wind fields serve to highlight the main characteristics of the observed system and to examine the momentum transports occuring in the system. The derived airflow structure shows classical characteristics, with an updraft flow in front of the system transporting low-level air to high levels and a downdraft airflow in the rear. The results to the momentum transports reveals that this system presents similar features of previously observed ones, such as: (i) the vertical transport of horizontal momentum normal to the convective line is countergradient resulting in a increase of its vertical shear; (ii) the vertical transport of line-parallel wind (v) is downgradient because the vertical divergence of the vertical v-momentum flux decreases the v-shear.
Mesoscale convective system; Momentum transport; EODD technique; TOGA-COARE
