Figure 10. cLCS for July with only currents (left panel), currents plus 1% windage (middle panel), and currents plus 2% windage (right panel).
To characterize particle distribution in zone 2, we considered the seasonal variability of both surface currents and cLCS. Therefore, we divided the results according to the different wind-forcing conditions.
With 1% windage, particles will reach zone 2 using the transport route defined by the cCLS in zone 4, which can be considered the CC continuance ending on the YP eastern coast. The cLCS continues towards the Yucatan Channel, giving rise to the LC. This suggests that the cLCS at zone 4 are a pathway for offshore particles (further from the continental shelf) to move towards the Yucatan Channel. Considering the cLCS seasonal variability, the particles are transported over the regions of maximum attraction located in zones 4 and 5 and up to zone 1. Regardless of the release month, it takes approximately 5 to 8 months for particles to reach zone 2 (Figure 11). The highest particle density for zone 2 occurs when particles are released between September and December, reaching the YP the following year and starting to cluster in April.
With 2% windage, particles are directed towards zone 2 by the cLCS in zone 4, moving over the continental shelf and into the coastal regions of Honduras and Belize before clustering in zone 2. Regardless of the release month, the particle’s arrival to zone 2 is between 4 and 8 months (Figure 11). In this case, there is considerable clustering independent of the release month. Nevertheless, when particles are released between March and June, there are a high number of months (> 5) with a very high confluence in zone 2. Particles released between these months arrive at the YP as soon as July, showing the highest density starting in September.
Notably, the arrival and distribution of particles in zone 2, observed in both HYCOM climatology and SOMs patterns (Figure 11), and the temporal variability of particle density are closely linked to seasonal changes in surface currents. Coastal geostrophic currents act as transport barriers, hindering transport perpendicular to the coast; therefore, the impact of wind is significant. When the wind blows perpendicular to the coast, it adds a cross-shelf component in the upper centimeters of the ocean due to windage or Stokes drift, in contrast with geostrophic currents that flow along isobaths (Brink, 2016). Thus wind allows particles to move perpendicular to the coast and cross the transport barriers caused by along-slope currents. Perhaps more accurately, the cross-shelf component due to wind erases the transport barriers imposed by the coastal Yucatan Current while forcing trajectories towards the coast (Figure 10).