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Abstract :
[en] A high-resolution (1/60 degree), three-dimensional numerical circulation model of the Cariaco basin (Venezuela) is constructed by nesting the Regional Ocean Modeling System (ROMS) in the 1/12 degree global Hybrid Coordinate Ocean Model (HYCOM). The Cariaco basin is a semi-enclosed trench located along the coast of Venezuela. Its maximum depth is about 1400 m, and it is connected to the open ocean by two shallow passages: the Centinela channel in the northwest (146 m depth) and the Tortuga channel in the northeast (135 m depth). The main objective of this work is to improve our knowledge of the Cariaco basin dynamics, and to understand how the basin is influenced by the Caribbean Sea. The nesting of the Cariaco model in HYCOM is therefore crucial for these analyses. First, the annual cycle of the basin is described, using the results from a 2004 hindcast. Then, two modes of interaction between the basin and the open ocean are studied: (i) the meanders and eddies that travel westward with the Caribbean Current, and (ii) a subsurface eastward current that flows along the South America north coast. The ventilation of the basin through its channels is analyzed by studying the annual variations of the thermocline depth in the basin channels. In addition to the improved knowledge of the Cariaco basin circulation, which can help to better understand the climate of the past through paleoceanographic studies, this work is also an example of the feasibility of one of the objectives of GODAE: downscaling from a large-scale model to a regional model. In particular, the nesting ratio of 5 used in this work (from 9 km down to 1.82 km) demonstrates that a high-resolution model can be successfully nested in HYCOM.
