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  • 1
    Online Resource
    Online Resource
    Deciphering the imprint of topology on nonlinear dynamical network stability (2017)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_25026
    Format: 1 Online-Ressource (15 Seiten)
    Content: Coupled oscillator networks show complex interrelations between topological characteristics of the network and the nonlinear stability of single nodes with respect to large but realistic perturbations. We extend previous results on these relations by incorporating sampling-based measures of the transient behaviour of the system, its survivability, as well as its asymptotic behaviour, its basin stability. By combining basin stability and survivability we uncover novel, previously unknown asymptotic states with solitary, desynchronized oscillators which are rotating with a frequency different from their natural one. They occur almost exclusively after perturbations at nodes with specific topological properties. More generally we confirm and significantly refine the results on the distinguished role tree-shaped appendices play for nonlinear stability. We find a topological classification scheme for nodes located in such appendices, that exactly separates them according to their stability properties, thus establishing a strong link between topology and dynamics. Hence, the results can be used for the identification of vulnerable nodes in power grids or other coupled oscillator networks. From this classification we can derive general design principles for resilient power grids. We find that striving for homogeneous network topologies facilitates a better performance in terms of nonlinear dynamical network stability. While the employed second-order Kuramoto-like model is parametrised to be representative for power grids, we expect these insights to transfer to other critical infrastructure systems or complex network dynamics appearing in various other fields.
    Content: Peer Reviewed
    In: [London] : IOP, 19,3
    Language: English
    DOI: 10.1088/1367-2630/aa6321
    DOI: 10.18452/24374
    URN: urn:nbn:de:kobv:11-110-18452/25026-4
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  • 2
    Online Resource
    Online Resource
    First Quantification of the Permafrost Heat Sink in the Earth's Climate System (2023)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_27651
    Format: 1 Online-Ressource (11 Seiten)
    ISSN: 0094-8276 , 1944-8007 , 0094-8276 , 1944-8007
    Content: Due to an imbalance between incoming and outgoing radiation at the top of the atmosphere, excess heat has accumulated in Earth's climate system in recent decades, driving global warming and climatic changes. To date, it has not been quantified how much of this excess heat is used to melt ground ice in permafrost. Here, we diagnose changes in sensible and latent ground heat contents in the northern terrestrial permafrost region from ensemble-simulations of a tailored land surface model. We find that between 1980 and 2018, about 3.9^+1.4_-1.6 ZJ of heat, of which 1.7_-1.4^+1.3 ZJ (44%) were used to melt ground ice, were absorbed by permafrost. Our estimate, which does not yet account for the potentially increased heat uptake due to thermokarst processes in ice-rich terrain, suggests that permafrost is a persistent heat sink comparable in magnitude to other components of the cryosphere and must be explicitly considered when assessing Earth's energy imbalance.
    Content: Peer Reviewed
    In: Hoboken, NJ : Wiley, 50,12, 0094-8276
    In: 1944-8007
    Language: English
    DOI: 10.18452/26963
    DOI: 10.1029/2022GL102053
    URN: urn:nbn:de:kobv:11-110-18452/27651-7
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  • 3
    Book
    Book
    Modelling the evolution of ice-rich permafrost landscapes in response to a warming climate / (2020)
    Berlin,
    Details
    UID:
    almahu_BV047337377
    Format: iii, 181 Seiten : , Illustrationen, Diagramme, Karten (überwiegend farbig).
    Note: Tag der mündlichen Prüfung: 12. November 2020 , Dissertation Humboldt-Universität zu Berlin 2020
    Additional Edition: Erscheint auch als Online-Ausgabe Nitzbon, Jan Modelling the evolution of ice-rich permafrost landscapes in response to a warming climate urn:nbn:de:kobv:11-110-18452/22872-8
    Language: English
    Subjects: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science
    RVK:
    RB 10372
    RVK:
    RQ 58372
    RVK:
    ZC 13176
    Keywords: Dauerfrostboden ; Klimaänderung ; Mathematisches Modell ; Mathematische Modellierung ; Dauerfrostboden ; Klimaänderung ; Hochschulschrift
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  • 4
    Online Resource
    Online Resource
    Modelling the evolution of ice-rich permafrost landscapes in response to a warming climate / (2020)
    Berlin,
    Details
    UID:
    almahu_BV047069192
    Format: 1 Online-Ressource (g, iii, 181 Seiten) : , Illustrationen, Diagramme, Karten.
    Note: Dissertation Humboldt-Universität zu Berlin 2020
    Additional Edition: Erscheint auch als Druck-Ausgabe Nitzbon, Jan Modelling the evolution of ice-rich permafrost landscapes in response to a warming climate
    Language: English
    Subjects: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science
    RVK:
    RB 10372
    RVK:
    RQ 58372
    RVK:
    ZC 13176
    Keywords: Dauerfrostboden ; Klimaänderung ; Mathematisches Modell ; Mathematische Modellierung ; Dauerfrostboden ; Klimaänderung ; Hochschulschrift
    DOI: 10.18452/22175
    URN: urn:nbn:de:kobv:11-110-18452/22872-8
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  • 5
    Online Resource
    Online Resource
    Pathways of ice-wedge degradation in polygonal tundra under different hydrological conditions (2019)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_29979
    Format: 1 Online-Ressource (35 Seiten)
    Content: Ice-wedge polygons are common features of lowland tundra in the continuous permafrost zone and prone to rapid degradation through melting of ground ice. There are many interrelated processes involved in ice-wedge thermokarst and it is a major challenge to quantify their influence on the stability of the permafrost underlying the landscape. In this study we used a numerical modelling approach to investigate the degradation of ice wedges with a focus on the influence of hydrological conditions. Our study area was Samoylov Island in the Lena River delta of northern Siberia, for which we had in situ measurements to evaluate the model. The tailored version of the CryoGrid 3 land surface model was capable of simulating the changing microtopography of polygonal tundra and also regarded lateral fluxes of heat, water, and snow. We demonstrated that the approach is capable of simulating ice-wedge degradation and the associated transition from a low-centred to a high-centred polygonal microtopography. The model simulations showed ice-wedge degradation under recent climatic conditions of the study area, irrespective of hydrological conditions. However, we found that wetter conditions lead to an earlier onset of degradation and cause more rapid ground subsidence. We set our findings in correspondence to observed types of ice-wedge polygons in the study area and hypothesized on remaining discrepancies between modelled and observed ice-wedge thermokarst activity. Our quantitative approach provides a valuable complement to previous, more qualitative and conceptual, descriptions of the possible pathways of ice-wedge polygon evolution. We concluded that our study is a blueprint for investigating thermokarst landforms and marks a step forward in understanding the complex interrelationships between various processes shaping ice-rich permafrost landscapes.
    Content: Peer Reviewed
    In: Katlenburg-Lindau : Copernicus, 13,4, Seiten 1089-1123
    Language: English
    DOI: 10.18452/29362
    DOI: 10.5194/tc-13-1089-2019
    URN: urn:nbn:de:kobv:11-110-18452/29979-6
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  • 6
    Online Resource
    Online Resource
    Fast response of cold ice-rich permafrost in northeast Siberia to a warming climate (2020)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_29980
    Format: 1 Online-Ressource (11 Seiten)
    Content: The ice- and organic-rich permafrost of the northeast Siberian Arctic lowlands (NESAL) has been projected to remain stable beyond 2100, even under pessimistic climate warming scenarios. However, the numerical models used for these projections lack processes which induce widespread landscape change termed thermokarst, precluding realistic simulation of permafrost thaw in such ice-rich terrain. Here, we consider thermokarst-inducing processes in a numerical model and show that substantial permafrost degradation, involving widespread landscape collapse, is projected for the NESAL under strong warming (RCP8.5), while thawing is moderated by stabilizing feedbacks under moderate warming (RCP4.5). We estimate that by 2100 thaw-affected carbon could be up to three-fold (twelve-fold) under RCP4.5 (RCP8.5), of what is projected if thermokarst-inducing processes are ignored. Our study provides progress towards robust assessments of the global permafrost carbon–climate feedback by Earth system models, and underlines the importance of mitigating climate change to limit its impacts on permafrost ecosystems.
    Content: Peer Reviewed
    In: [London] : Nature Publishing Group UK, 11,1
    Language: English
    DOI: 10.18452/29363
    DOI: 10.1038/s41467-020-15725-8
    URN: urn:nbn:de:kobv:11-110-18452/29980-6
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  • 7
    Online Resource
    Online Resource
    Effects of multi-scale heterogeneity on the simulated evolution of ice-rich permafrost lowlands under a warming climate (2021)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_29981
    Format: 1 Online-Ressource (24 Seiten)
    Content: In continuous permafrost lowlands, thawing of ice-rich deposits and melting of massive ground ice lead to abrupt landscape changes called thermokarst, which have widespread consequences on the thermal, hydrological, and biogeochemical state of the subsurface. However, macro-scale land surface models (LSMs) do not resolve such localized subgrid-scale processes and could hence miss key feedback mechanisms and complexities which affect permafrost degradation and the potential liberation of soil organic carbon in high latitudes. Here, we extend the CryoGrid 3 permafrost model with a multi-scale tiling scheme which represents the spatial heterogeneities of surface and subsurface conditions in ice-rich permafrost lowlands. We conducted numerical simulations using stylized model setups to assess how different representations of micro- and meso-scale heterogeneities affect landscape evolution pathways and the amount of permafrost degradation in response to climate warming. At the micro-scale, the terrain was assumed to be either homogeneous or composed of ice-wedge polygons, and at the meso-scale it was assumed to be either homogeneous or resembling a low-gradient slope. We found that by using different model setups and parameter sets, a multitude of landscape evolution pathways could be simulated which correspond well to observed thermokarst landscape dynamics across the Arctic. These pathways include the formation, growth, and gradual drainage of thaw lakes; the transition from low-centred to high-centred ice-wedge polygons; and the formation of landscape-wide drainage systems due to melting of ice wedges. Moreover, we identified several feedback mechanisms due to lateral transport processes which either stabilize or destabilize the thermokarst terrain. The amount of permafrost degradation in response to climate warming was found to depend primarily on the prevailing hydrological conditions, which in turn are crucially affected by whether or not micro- and/or meso-scale heterogeneities were considered in the model setup. Our results suggest that the multi-scale tiling scheme allows for simulating ice-rich permafrost landscape dynamics in a more realistic way than simplistic one-dimensional models and thus facilitates more robust assessments of permafrost degradation pathways in response to climate warming. Our modelling work improves the understanding of how micro- and meso-scale processes affect the evolution of ice-rich permafrost landscapes, and it informs macro-scale modellers focusing on high-latitude land surface processes about the necessities and possibilities for the inclusion of subgrid-scale processes such as thermokarst within their models.
    Content: Peer Reviewed
    In: Katlenburg-Lindau : Copernicus, 15,3, Seiten 1399-1422
    Language: English
    DOI: 10.18452/29364
    DOI: 10.5194/tc-15-1399-2021
    URN: urn:nbn:de:kobv:11-110-18452/29981-2
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  • 8
    Online Resource
    Online Resource
    Heat stored in the Earth system 1960–2020: where does the energy go? (2023)
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    Details
    UID:
    gbv_1880481200
    Format: Diagramme
    ISSN: 1866-3516
    In: Earth system science data, Katlenburg-Lindau : Copernics Publications, 2009, 15(2023), 4, Seite 1675-1709, 1866-3516
    In: volume:15
    In: year:2023
    In: number:4
    In: pages:1675-1709
    Language: English
    DOI: 10.5194/essd-15-1675-2023
    URL: lizenzpflichtig
    Author information: Hendricks, Stefan
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