title: A perturbation-theoretic approach to Lagrangian flow networks.
abstract: Complex network approaches have been successfully applied for studying transport processes in complex systems ranging from road, railway, or airline infrastructures over industrial manufacturing to fluid dynamics. Here, we utilize a generic framework for describing the dynamics of geophysical flows such as ocean currents or atmospheric wind fields in terms of Lagrangian flow networks. In this approach, information on the passive advection of particles is transformed into a Markov chain based on transition probabilities of particles between the volume elements of a given partition of space for a fixed time step. We employ perturbation-theoretic methods to investigate the effects of modifications of transport processes in the underlying flow for three different problem classes: efficient absorption (corresponding to particle trapping or leaking), constant input of particles (with additional source terms modeling, e.g., localized contamination), and shifts of the steady state under probability mass conservation (as arising if the background flow is perturbed itself). Our results demonstrate that in all three cases, changes to the steady state solution can be analytically expressed in terms of the eigensystem of the unperturbed flow and the perturbation itself. These results are potentially relevant for developing more efficient strategies for coping with contaminations of fluid or gaseous media such as ocean and atmosphere by oil spills, radioactive substances, non-reactive chemicals, or volcanic aerosols.
authors.affiliation: Center for Spatial Information Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kahshiwa-shi, Chiba 277-8568, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Fujiwara
authors.affiliation: Research Domain IV-Transdisciplinary Concepts and Methods, Potsdam Institute for Climate Impact Research, Telegrafenberg A31, 14473 Potsdam, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Kirchen
authors.affiliation: Research Domain I-Earth System Analysis, Potsdam Institute for Climate Impact Research, Telegrafenberg A31, 14473 Potsdam, Germany.
authors.forename: Jonathan F
authors.initials: JF
authors.lastname: Donges
authors.affiliation: Research Domain IV-Transdisciplinary Concepts and Methods, Potsdam Institute for Climate Impact Research, Telegrafenberg A31, 14473 Potsdam, Germany.
authors.forename: Reik V
authors.initials: RV
authors.lastname: Donner