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DY: Fachverband Dynamik und Statistische Physik

DY 56: Poster: Glasses; Granular Matter; Brownian Motion and Anomalous Diffusion

DY 56.12: Poster

Donnerstag, 19. März 2020, 15:00–18:00, P1A

Coexistence of fixed and active dunes from numerical simulations — Maria Determann and •Eric Josef Ribeiro Parteli — Department of Geosciences, University of Cologne

The side-by-side coexistence of fixed and active Aeolian dunes in many environmental settings of the Earth defies our understanding of dune mobility as proxy for regional climate and environmental conditions. According to this understanding, fixed dunes prevail if the characteristic vegetation cover growth rate in a given region exceeds twice the rate of surface erosion and deposition processes caused by Aeolian transport, while dunes are predicted active otherwise. Here we show, by means of numerical simulations, that coexistence between stabilized and active dunes can be explained by climate-driven oscillations in atmospheric forcing relative to stabilizing vegetation growth conditions. The underlying factor for this co-existence is the hysteresis in the stabilization process of Aeolian dunes, i.e., much stronger winds are needed to reactivate fixed dunes than the ones required to stabilize them. Our simulations reproduce regional patterns of coexisting fixed and active dunes occurring under seasonal oscillation of rainfall and wind power, without requirement of any assumption on spatial heterogeneities in soil fertitility.