Coastal Surface Connectivity Of The Gulf Of Mexico From Transition Matrices.

With the objective of knowing the coastal-neritic surface connectivity of the Gulf of Mexico, and specifically of Perdido region, connectivity matrices have been obtained based on a discrete transfer operator or transition matrix (representation of the dynamics through Markov chains) that allows to identify regions where there is greater exchange of passive particles (larvae without behavior, passive tracer, pollutant), the regions that tend to retain them, as well as identify the temporal scales at which that exchange occurs. 20 years of two-dimensional daily mean surface velocity fields of three models (HYCOM, ROMS and NEMO) have been used to generate the database of particle trajectories in order to build the transition matrices for 3 seasons of the year (“Dry”, “Nortes” and “Rains”). The continental shelf was divided into 12 regions, and the corresponding transition matrix was used to propagate a uniformly distributed passive tracer in each region, and thus obtain the probabilistic evolution of that distribution as a function of time. The results show that there is low connectivity between regions in the shelf and those offshore, regardless of the season analyzed, due to the high retention capacity of the shelf regions or the low capacity to export particles to other regions. The minimum arrival time of a tracer to adjacent regions is less than 5 days, but in general, it is greater than 20 days for the farthest regions. The connectivity of the region of Perdido off Tamaulipas with other shelf regions occurs predominantly in the northbound direction (continental shelf of Louisiana and Texas), with a maximum probability between 25 and 35%, in a period of 5 to 15 days for the seasons of “Rains” and “Nortes”, and less than 5 days for the “Dry” season. There is no connectivity from the continental shelf of Perdido to the coastal regions of the Bay of Campeche, neither to the regions of the eastern shelf of the United States. Finally, a comparison with connectivity matrices obtained from the historical drifter register (from June 1993 to May 2018) will be shown.