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).