5 Conclusions
This work identified the transport routes from the Equatorial Atlantic
to the YP using Lagrangian experiments correlated to the cLCS. We used
climatological currents from HYCOM and the most recurrent surface
current patterns obtained from the climatological SOMs analysis for
those experiments. The cLCS were calculated for the entire domain, and
the transport barriers were determined, emphasizing the CS to interpret
the distribution of particles in that area. We delimited ten strategic
areas based on transport barriers, for which the area adjacent to the YP
east coast was studied in detail.
We found that the SOMs reproduce the characteristic patterns of surface
currents climate variability while the cLCS identified recurrent
trajectories and persistent transport barriers, as confirmed with
Lagrangian particle release experiments. The cLCS show a yearly
persistence indicating mesoscale patterns in surface transport and a
surface transport barrier isolating the continental shelf from
circulation beyond the shelf break. Integrating these results with the
Lagrangian experiments, we found that the cLCS determine particle
trajectories since they function as transport pathways and transport
barriers. When the cLCS act as transport barriers, particles are
restrained from reaching specific areas unless there is windage to
debilitate or completely erase the cLCS transport barriers due to
currents.
Our results show that wind is a needed condition for particle confluence
within different regions of the CS, either representative of the effect
of windage or Stokes drift. For the regions of the Yucatan Channel,
Honduras-Jamaica Central Channel, Honduras-Jamaica East Channel, and
Jamaica-Haiti Channel, the 1% windage is necessary, while the 2%
windage is needed for the particles to reach Quintana Roo, Mexico,
Honduras-Jamaica West Channel, Southern Lesser Antilles, and Central
America. From the Equatorial Atlantic region, the particles will take
approximately four to eight months to reach the YP and will be
influenced by the atmosphere phenomena and the space-time cLCS
variability, being the Honduras-Jamaica West Channel, the main passage
of particles transported towards the peninsula. The particles released
during the autumn-winter months with a 1% windage are those that reach
Quintana Roo, Mexico coasts in the spring of the following year, while
the particles released in the spring months with a 2% windage are those
that reach this zone in the summer months of the same year. The higher
arrival of sargassum to the Mexican Caribbean in the summer months
reaffirms the importance of the 2% windage for particles to arrive in
this area.
This spatio-temporal particle distribution is similar whether using the
HYCOM climatological data or the current patterns obtained with the
SOMs. In addition to the hydrodynamics that determines the trajectory of
particulate matter in the ocean, another important result is the
representation of ocean climate by SOMs. The seasonality in the surface
circulation is clearly illustrated by the BMUs distribution. From a
numerical model perspective, the SOMs approach, together with the cLCS
and its interaction with the large-scale dynamical atmospheric
circulation features, can be applied to study and improve the
representation of physical processes and approximate particulate matter
transport and distribution on the sea surface. Atmospheric phenomena
such as the easterly waves, anticyclonic cold fronts, Caribbean
Low-Level Jet, the trade winds, and the ITCZ influence particle
distribution, confluence, and aggregation. A more detailed study is
required to determine the influence on windage of each of these
phenomena.
Forecasting particle matter trajectories on the ocean still requires
further studies to reproduce the transport accurately, incorporating
other processes, such as degradation, growth, mortality, etc..
Nevertheless, this study is an advance in implementing different
analysis methods of the interaction between different processes that
determine ocean surface dynamics and their effect on particle transport.