4 research outputs found
Lagrangian dynamical geography of the Gulf of Mexico
We construct a Markov-chain representation of the surface-ocean Lagrangian
dynamics in a region occupied by the Gulf of Mexico (GoM) and adjacent portions
of the Caribbean Sea and North Atlantic using satellite-tracked drifter
trajectory data, the largest collection so far considered. From the analysis of
the eigenvectors of the transition matrix associated with the chain, we
identify almost-invariant attracting sets and their basins of attraction. With
this information we decompose the GoM's geography into weakly dynamically
interacting provinces, which constrain the connectivity between distant
locations within the GoM. Offshore oil exploration, oil spill contingency
planning, and fish larval connectivity assessment are among the many activities
that can benefit from the dynamical information carried in the geography
constructed here.Comment: Submitted to Scientific Report
Temporal variability of chlorophyll distribution in the Gulf of Mexico: bio-optical data from profiling floats
Chlorophyll concentration is a key oceanic biogeochemical
variable. In the Gulf of Mexico (GOM), its distribution, which is mainly
obtained from satellite surface observations and scarce in situ experiments,
is still poorly understood. In 2011ā2012, eight profiling floats equipped
with biogeochemical sensors were deployed for the first time in the GOM and
generated an unprecedented dataset that significantly increased the number of
chlorophyll vertical distribution measurements in the region. The analysis of
these data, once calibrated, permits us to reconsider the spatial and
temporal variability of the chlorophyll concentration in the water column. At
a seasonal scale, results confirm the surface signal seen by satellites,
presenting maximum concentrations in winter and low values in summer. It is
shown that the deepening of the mixed layer is the primary factor triggering
the chlorophyll surface increase in winter. In the GOM, a possible
interpretation is that this surface increase corresponds to a biomass
increase. However, the present dataset suggests that the basin-scale
climatological surface increase in chlorophyll content results from a
vertical redistribution of subsurface chlorophyll and/or photoacclimation
processes, rather than a net increase of biomass. One plausible explanation
for this is the decoupling between the mixed-layer depth and the deep
nutrient reservoir since mixed-layer depth only reaches the nitracline in
sporadic events in the observations. Float measurements also provide evidence
that the depth and the magnitude of the deep chlorophyll maximum is strongly
controlled by the mesoscale variability, with higher chlorophyll biomass
generally observed in cyclones rather than anticyclones