The plots displayed on this page show float trajectories in various layers and released at three different locations during the year 1980. Those trajectories are obtained from the very high resolution MICOM simulation forced daily by ECMWF winds. The release locations are chosen according to the Loop Current regime and the position of the Loop Current ring. For the three release experiments the Loop Current is in the port-toport regime. All the release lines are meridional. On day 111 and at 89W the first release is completed across the core of the Loop Current ring. The second one is located at 86W and is completed on day 135. During the same regime, starting the same day, another release line is located at 87.5W, which is just in the lee path of the Loop Current ring. The layers targeted in these experiments correspond to the depth where the mean circulation was calculated (see Mean horizontal Circulation). Therefore, layer 7 and 8 contain the depth 400m, layer 12 contain the depth 900, layer 12 and 13, the depths 1100-1500m and layer 14 the depth 2000m.

General comments about the plots

In most of the plots, the starting point of a trajectory is marked by an empty black square. The end of the trajectory is marked by a star. From left to rigth, each plot displays the float trajectories after release at 86W, 87.5W and 89W respectively. The backgroung vector plot is a snapshot of the circulation at the release day in the corresponding layer.

Surface float trajectories

Figure 1 Figure 2 Figure 3

The main features in the three plots are the cyclonic and anticyclonic gyres in the western Gulf. Even though the two gyres appear as permanent features, the begining of the trajectories differ according to the starting line. Indeed, some of the floats released at 86W follow a cyclonic path just east of the Loop Current Ring (Fig. 1). To the contrary, floats released closer to the Loop Current ring or inside follow an anticyclonic path (see Fig. 2 and 3).

Circulation in layer 7

Figure 4 Figure 5 Figure 6

The three figures show examples of soutwestward trajectories and even cyclonic trajectories. They are independent of the longitude of the release location but they depend on the release latitude. Nevertheless, some of the floats released uptream of the Loop Current ring end in the southwest cyclonic gyre whyle none of them released at the longitude of the eddy core show a cyclonic trajectory in this area.

Circulation in layer 8

Figure 7 Figure 8 Figure 9

In layer 8 the same soutwestward and cyclonic trajectories are observed (see Fig. 8 and 9) but this time for floats released in the vicinity of the Loop current ring and across the core of the ring. Floats released in the eastern Gulf are entrained in a small anticyclonic gyre in the northern part of the center of the Gulf of Mexico (Fig. 7). In both layers the soutwestward trajectories originate from a westward current on the continental slope of the Mississipi area.

Circulation in layer 12

Figure 10 Figure 11 Figure 12

The trajectories in layer 12 undergo a cyclonic motion or move southwestward as they were released close to the Loop Current Ring (Fig.e 11 and 12). As in the above layers, the floats concerned were released in the northern part the Gulf. In Figure 10, floats released further south display a westward drift with a meridional divergence on the western end of the Gulf of Mexico. Also, north released floats undergo small cyclonic motions.

Circulation in layer 13

Figure 13

Inside GOM cyclonic motion (floats released at 87.5W)

Figure 14 Figure 15

Outflow

Figure 16

Southwestward boundary current

The above trajectories reveal the complexity of the circulation in the deep layers but also shed some light on the exchange of water between the Gulf of Mexico and the Caribbean Sea. Indeed, floats released upstream of the ring core and in the northern half of the deep Gulf, exit the Gulf of Mexico through the Yucatan Channel (Fig. 14 and 15). Floats releases south follow a cyclonic path (Fig 13). On the other hand, floats released at the south of the eddy are trapped in a southwestward boundary current (Fig. 16).

Circulation in layer 14

Figure 17 Figure 18 Figure 18

All the floats, whatever the released location is, undergo cyclonic loops and motions. But their journey is restricted to a zonal line and they don't circle arroung the Gulf of Mexico. Releasing some floats in the southwest basin of the gulf in a future experiment will shed some light on the bottom circulation in this region of the Gulf.