@article{vonLindheimHarikrishnanDoerffeletal.2021, author = {von Lindheim, Johannes and Harikrishnan, Abhishek and D{\"o}rffel, Tom and Klein, Rupert and Koltai, Peter and Mikula, Natalia and M{\"u}ller, Annette and N{\´e}vir, Peter and Pacey, George and Polzin, Robert and Vercauteren, Nikki}, title = {Definition, detection and tracking of persistent structures in atmospheric flows}, journal = {arXiv}, arxiv = {http://arxiv.org/abs/2111.13645}, year = {2021}, abstract = {Long-lived flow patterns in the atmosphere such as weather fronts, mid-latitude blockings or tropical cyclones often induce extreme weather conditions. As a consequence, their description, detection, and tracking has received increasing attention in recent years. Similar objectives also arise in diverse fields such as turbulence and combustion research, image analysis, and medical diagnostics under the headlines of "feature tracking", "coherent structure detection" or "image registration" - to name just a few. A host of different approaches to addressing the underlying, often very similar, tasks have been developed and successfully used. Here, several typical examples of such approaches are summarized, further developed and applied to meteorological data sets. Common abstract operational steps form the basis for a unifying framework for the specification of "persistent structures" involving the definition of the physical state of a system, the features of interest, and means of measuring their persistence.}, language = {en} } @article{MironBeronVeraHelfmannetal.2021, author = {Miron, Philippe and Beron-Vera, Francisco and Helfmann, Luzie and Koltai, P{\´e}ter}, title = {Transition paths of marine debris and the stability of the garbage patches}, volume = {31}, journal = {Chaos: An Interdisciplinary Journal of Nonlinear Science}, number = {3}, arxiv = {http://arxiv.org/abs/2009.11234}, doi = {https://doi.org/10.1063/5.0030535}, year = {2021}, abstract = {We used transition path theory (TPT) to infer "reactive" pathways of floating marine debris trajectories. The TPT analysis was applied on a pollution-aware time-homogeneous Markov chain model constructed from trajectories produced by satellite-tracked undrogued buoys from the NOAA Global Drifter Program. The latter involved coping with the openness of the system in physical space, which further required an adaptation of the standard TPT setting. Directly connecting pollution sources along coastlines with garbage patches of varied strengths, the unveiled reactive pollution routes represent alternative targets for ocean cleanup efforts. Among our specific findings we highlight: constraining a highly probable pollution source for the Great Pacific Garbage Patch; characterizing the weakness of the Indian Ocean gyre as a trap for plastic waste; and unveiling a tendency of the subtropical gyres to export garbage toward the coastlines rather than to other gyres in the event of anomalously intense winds.}, language = {en} }