BAROCLINIC FLOWS, TRANSPORTS, AND KINEMATIC PROPERTIES IN A CYCLONIC-ANTICYCLONIC-CYCLONIC RING TRIAD IN THE GULF-OF-MEXICO

During October-November 1986 the baroclinic circulation of the central and western Gulf of Mexico was dominated by an anticyclonic ring that was being bisected by two north and south flanking cyclonic rings. Th e baroclinic circulation revealed a well-defined cyclonic-anticyclonic -cyclonic triad system. The anticyclone's collision against the wester n gulf continental slope at 22.5-degrees-N, 97-degrees-W originated th e north and south flanking cyclonic rings. The weakening of the anticy clone's relative vorticity, during the collision, was compensated by a long-shelf north (26 cm s-1) and south (58 cm s-1) jet currents and by the anticyclone's flanking water mass's gain of cyclonic vorticity fr om lateral shear contributed by east (56 cm s-1) and west (42 cm s-1) current jets with individual mass transports of approximately 18 Sv. W ithin the 0-1000 and 0-500 dbar layers and across 96-degrees-W the mag nitudes of the colliding westward transports were 17.80 and 8.59 Sv, r espectively. These corresponding transports were 85 and 94% balanced b y along-shelf jet currents north and south of the anticyclone's collis ion zone. This indicates that only minor amounts (<15%) of the anticyc lone's colliding westward transports might have flowed into the wester n gulf s continental shelf water mass or else they sank into deeper wa ter along the continental slope during the anticyclone's collision eve nt. The resultant effect of the coupled interaction between the anticy clone and the cyclonic pair was the surging of the water mass in the c yclones and its sinking in the anticyclone. This mechanism controlled the magnitude, direction, location of vertical advection, and transfer of kinetic energy from the upper to the deeper water layers. Our vert ical transport estimates through the 1000-m-depth surface revealed a n et vertical descending transport of 0.4 Sv for the ring triad system. This mass flux occurred primordially within the south central gulf reg ion and most likely constituted a principal mechanism that propelled t he gulf s deep horizontal circulation. The volume renewal time is appr oximately 5 years for the ring triad system within 0-1000 dbar. The vo lume renewal time for the gulf s deep water layer (2000-3000 dbar), es timated as a function of its horizontal outflowing mass flux (1.96 Sv) , is of the same order of magnitude and reveals that the deeper layer of the Gulf of Mexico is as well ventilated as its upper layer (0-1000 dbar). The ring triad's surface kinematic properties were derived fro m the sea surface baroclinic circulation field referenced to 500 dbar. Within this layer, individual ring geometries were conserved. Maximum tangential ring velocities were 60 and 58 cm s-1, for the north and s outh cyclones respectively, and 30 cm s-1 for the anticyclone. The cor responding periods of revolution were 16, 19, and 26 days, and vertica l velocities calculated at the rings' peripheries, where maximum horiz ontal divergence was encountered, were 1. 5, 1.0, and -1.0 m d-1.