Grouping of the Markov-chain states into classes according to their communication type. Bins indicated with the same color belong to the same class. The are 31 communicating classes covering the eGoM domain. Two of these classes are closed (red boxes) and 2 are both closed and absorbing (black boxes); they do not offer any insight into the Lagrangian dynamics other than mere beaching of drifters. Computations carried using Matlab R2017a (http://www.mathworks.com/) and visualization using Tecplot 360 2016 R2 (http://www.tecplot.com/).