Browsing Institutt for geofag by Author "Aas, Kjetil Schanke"

Now showing items 1-15 of 15

  • Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard 
    Jakob Fürst, Johannes; Gillet-Chaulet, Fabien; Benham, Toby; Dowdeswell, Julian A.; Grabiec, Mariusz; Navarro, Francisco; Pettersson, Rickard; Moholdt, Geir; Nuth, Christopher; Sass, Björn; Aas, Kjetil Schanke; Fettweis, Xavier; Lang, Charlotte; Seehaus, Thorsten; Braun, Matthias (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    The basal topography is largely unknown beneath most glaciers and ice caps, and many attempts have been made to estimate a thickness field from other more accessible information at the surface. Here, we present a two-step ...
  • Climate–ecosystem modelling made easy: The Land Sites Platform 
    Keetz, Lasse Torben; Lieungh, Eva; Karimi-Asli, Kaveh; Geange, Sonya Rita; Gelati, Emiliano; Tang, Hui; Yilmaz, Yeliz A.; Aas, Kjetil Schanke; Althuizen, Inge; Bryn, Anders; Falk, Stefanie; Fisher, Rosie; Fouilloux, Anne; Horvath, Peter; Indrehus, Sunniva; Lee, Hanna; Lombardozzi, Danica; Parmentier, Frans-Jan W.; Pirk, Norbert; Vandvik, Vigdis; Vollsnes, Ane Victoria; Skarpaas, Olav; Stordal, Frode; Tallaksen, Lena M. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Dynamic Global Vegetation Models (DGVMs) provide a state-of-the-art process-based approach to study the complex interplay between vegetation and its physical environment. For example, they help to predict how terrestrial ...
  • Explicitly modelling microtopography in permafrost landscapes in a land surface model (JULES vn5.4_microtopography) 
    Smith, Noah D.; Burke, Eleanor J.; Aas, Kjetil Schanke; Althuizen, Inge; Boike, Julia; Christiansen, Casper Tai; Etzelmüller, Bernd; Friborg, Thomas; Lee, Hanna; Rumbold, Heather; Turton, Rachael H.; Westermann, Sebastian; Chadburn, Sarah E. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    Microtopography can be a key driver of heterogeneity in the ground thermal and hydrological regime of permafrost landscapes. In turn, this heterogeneity can influence plant communities, methane fluxes, and the initiation ...
  • Inclusion of a cold hardening scheme to represent frost tolerance is essential to model realistic plant hydraulics in the Arctic-boreal zone in CLM5.0-FATES-Hydro 
    Lambert, Marius; Tang, Hui; Aas, Kjetil Schanke; Stordal, Frode; Fisher, Rosie; Fang, Yilin; Ding, Junyan; Parmentier, Frans-Jan W. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    As temperatures decrease in autumn, vegetation of temperate and boreal ecosystems increases its tolerance to freezing. This process, known as hardening, results in a set of physiological changes at the molecular level that ...
  • Integration of a Frost Mortality Scheme Into the Demographic Vegetation Model FATES 
    Lambert, Marius; Tang, Hui; Aas, Kjetil Schanke; Stordal, Frode; Fisher, Rosie; Bjerke, Jarle Werner; Holm, Jennifer A.; Parmentier, Frans-Jan (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Frost is damaging to plants when air temperature drops below their tolerance threshold. The set of mechanisms used by cold-tolerant plants to withstand freezing is called “hardening” and typically take place in autumn to ...
  • Lateral thermokarst patterns in permafrost peat plateaus in northern Norway 
    Martin, Leo Celestin Paul; Nitzbon, Jan; Scheer, Johanna; Aas, Kjetil Schanke; Eiken, Trond; Langer, Moritz; Filhol, Simon; Etzelmüller, Bernd; Westermann, Sebastian (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
    Subarctic peatlands underlain by permafrost contain significant amounts of organic carbon. Our ability to quantify the evolution of such permafrost landscapes in numerical models is critical for providing robust predictions ...
  • Overview of the Norwegian Earth System Model (NorESM2) and key climate response of CMIP6 DECK, historical, and scenario simulations 
    Seland, Øyvind; Bentsen, Mats; Oliviè, Dirk Jan Leo; Toniazzo, Thomas; Gjermundsen, Ada; Graff, Lise Seland; Debernard, Jens Boldingh; Gupta, Alok Kumar; He, Yan-Chun; Kirkevåg, Alf; Schwinger, Jörg; Tjiputra, Jerry; Aas, Kjetil Schanke; Bethke, Ingo; Fan, Yuanchao; Griesfeller, Jan; Grini, Alf; Guo, Chuncheng; Ilicak, Mehmet; Karset, Inger Helene H.; Landgren, Oskar Andreas; Liakka, Johan; Moseid, Kine Onsum; Nummelin, Aleksi; Spensberger, Clemens; Tang, Hui; Zhang, Zhongshi; Heinze, Christoph; Iversen, Trond; Schulz, Michael (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    Abstract. The second version of the coupled Norwegian Earth System Model (NorESM2) is presented and evaluated. NorESM2 is based on the second version of the Community Earth System Model (CESM2) and shares with CESM2 the ...
  • Pathways of ice-wedge degradation in polygonal tundra under different hydrological conditions 
    Nitzbon, Jan; Langer, Moritz; Westermann, Sebastian; Martin, Leo Celestin Paul; Aas, Kjetil Schanke; Boike, Julia (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Abstract. 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 ...
  • Projecting circum-Arctic excess-ground-ice melt with a sub-grid representation in the Community Land Model 
    Cai, Lei; Lee, Hanna; Aas, Kjetil Schanke; Westermann, Sebastian (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    To address the long-standing underrepresentation of the influences of highly variable ground ice content on the trajectory of permafrost conditions simulated in Earth system models under a warming climate, we implement a ...
  • Regional-scale phytoplankton dynamics and their association with glacier meltwater runoff in Svalbard 
    Dunse, Thorben; Dong, Kaixing; Aas, Kjetil Schanke; Stige, Leif Christian (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    Arctic amplification of global warming has accelerated mass loss of Arctic land ice over the past decades and led to increased freshwater discharge into glacier fjords and adjacent seas. Glacier freshwater discharge is ...
  • Simulating the climatic mass balance of Svalbard glaciers from 2003 to 2013 with a high-resolution coupled atmosphere-glacier model 
    Aas, Kjetil Schanke; Dunse, Thorben; Collier, E.; Schuler, Thomas; Berntsen, Terje Koren; Kohler, Jack; Luks, B. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    In this study we simulate the climatic mass bal- ance of Svalbard glaciers with a coupled atmosphere–glacier model with 3 km grid spacing, from September 2003 to September 2013. We find a mean specific net ...
  • Stability Conditions of Peat Plateaus and Palsas in Northern Norway 
    Martin, Leo Celestin Paul; Nitzbon, Jan; Aas, Kjetil Schanke; Etzelmüller, Bernd; Kristiansen, Håvard; Westermann, Sebastian (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Peat plateaus and palsas are characteristic morphologies of sporadic permafrost, and the transition from permafrost to permafrost‐free ground typically occurs on spatial scales of meters. They are particularly vulnerable ...
  • Thaw processes in ice-rich permafrost landscapes represented with laterally coupled tiles in a land surface model 
    Aas, Kjetil Schanke; Martin, Leo Celestin Paul; Nitzbon, Jan; Langer, Moritz; Boike, Julia; Lee, Hanna; Berntsen, Terje Koren; Westermann, Sebastian (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Earth system models (ESMs) are our primary tool for projecting future climate change, but their ability to represent small-scale land surface processes is currently limited. This is especially true for permafrost landscapes ...
  • The climatic mass balance of Svalbard glaciers: A 10-year simulation with a coupled atmosphere-glacier mass balance model 
    Aas, Kjetil Schanke; Dunse, Thorben; Collier, E.; Schuler, Thomas; Berntsen, Terje Koren; Kohler, Jack; Luks, Bartlomiej (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2016)
    In this study we simulate the climatic mass balance of Svalbard glaciers with a coupled atmosphere–glacier model with 3 km grid spacing, from September 2003 to September 2013. We find a mean specific net mass balance of ...
  • A Tiling Approach to Represent Subgrid Snow Variability in Coupled Land Surface–Atmosphere Models 
    Aas, Kjetil Schanke; Gisnås, Kjersti; Westermann, Sebastian; Berntsen, Terje Koren (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    A mosaic approach to represent subgrid snow variation in a coupled atmosphere–land surface model (WRF–Noah) is introduced and tested. Solid precipitation is scaled in 10 subgrid tiles based on precalculated snow distributions, ...