A numerical simulation of the two- and three-dimensional Lagrangian circulation in the northern Gulf of California

The surface circulation in the northern Gulf of California is dominated by a cyclonic gyre during summer and an anticyclonic gyre during winter. The associated 3D Lagrangian circulation is calculated and compared with that detected by surface floats by inhibiting vertical advection in a three-dimensional (3D) numerical model. In general, the 3D circulation follows the same horizontal paths as in the two-dimensional (2D) case but with vertical excursions along the trajectories. However, in some areas, especially those close to the coasts which represents ∼20% of the study area, the vertical displacements cause the paths of both cases (with and without vertical advection) to differ considerably, thus resulting in different destinations for the particles. This finding is of relevance for the fate of larvae or contaminants in the area, which so far had been studied on the basis of 2D results alone.