Sebastian Westermann

• Etzelmüller, Bernd; Patton, Henry; Schomacker, Anders; Czekirda, Justyna; Girod, Luc Maurice Ramuntcho; Hubbard, Alun Lloyd; Lilleøren, Karianne Staalesen & Westermann, Sebastian (2020). Icelandic permafrost dynamics since the Last Glacial Maximum – model results and geomorphological implications. Quaternary Science Reviews.  ISSN 0277-3791.  233:106236, s 1- 15 . doi: 10.1016/j.quascirev.2020.106236 Full text in Research Archive. Show summary

  Iceland’s periglacial realm is one of the most dynamic on the planet, with active geomorphologicalprocesses and high weathering rates of young bedrock resulting in high sediment yields and ongoingmass movement. Permafrost is discontinuous in Iceland’s highlands and mountains over c. 800 m a.s.l,and sporadic in palsa mires in the central highlands. During the late Pleistocene and Holocene, Iceland’speriglacial environment varied considerably in time and space, dominated by glacialfluctuations andperiglacial processes. To evaluate the dynamics of permafrost in Iceland since the last deglaciation, weuse the output of a coupled climate/ice sheet model to force a transient permafrost model (CryoGRID 2)from the Last Glacial Maximum (LGM) through to the present. Wefind that permafrost was widespreadacross the deglaciated areas of western, northern and eastern Iceland after the LGM, and that up to 20% ofIceland’s terrestrial area was underlain by permafrost throughout the late Pleistocene. This influencedgeomorphological processes and landform generation: the early collapse of the marine-based ice sheettogether with the aggradation of permafrost in these zones initiated the formation of abundant and nowrelict rock glaciers across coastal margins. Permafrost degraded rapidly after the Younger Dryas, with amarked impact on slope stability. Permafrost that formed during the Little Ice Age is again thawingrapidly, and an escalation in slope failure and mass-movement might be currently underway. Our studydemonstrates that large regions of Iceland have been underlain by permafrost for millennia, facilitatinglandform development and influencing the stability of steep slopes

• Aalstad, Kristoffer; Westermann, Sebastian & Bertino, Laurent (2020). Evaluating satellite retrieved fractional snow-covered area at a high-Arctic site using terrestrial photography. Remote Sensing of Environment.  ISSN 0034-4257.  239 . doi: 10.1016/j.rse.2019.111618 Full text in Research Archive.
• Obu, Jaroslav; Westermann, Sebastian & Kääb, Andreas (2020). Pan-Antarctic map of near-surface permafrost temperatures at 1 km2 scale. The Cryosphere.  ISSN 1994-0416.  14, s 497- 519 . doi: https://doi.org/10.5194/tc-14-497-2020 Show summary

  Permafrost is present within almost all of the Antarctic's ice-free areas, but little is known about spatial variations in permafrost temperatures except for a few areas with established ground temperature measurements. We modelled a temperature at the top of the permafrost (TTOP) for all the ice-free areas of the Antarctic mainland and Antarctic islands at 1 km2 resolution during 2000–2017. The model was driven by remotely sensed land surface temperatures and downscaled ERA-Interim climate reanalysis data, and subgrid permafrost variability was simulated by variable snow cover. The results were validated against in situ-measured ground temperatures from 40 permafrost boreholes, and the resulting root-mean-square error was 1.9 ∘C. The lowest near-surface permafrost temperature of −36 ∘C was modelled at Mount Markham in the Queen Elizabeth Range in the Transantarctic Mountains. This is the lowest permafrost temperature on Earth, according to global-scale modelling results. The temperatures were most commonly modelled between −23 and −18 ∘C for mountainous areas rising above the Antarctic Ice Sheet and between −14 and −8 ∘C for coastal areas. The model performance was good where snow conditions were modelled realistically, but errors of up to 4 ∘C occurred at sites with strong wind-driven redistribution of snow.

• Aas, Kjetil Schanke; Martin, Leo Celestin Paul; Nitzbon, Jan; Langer, Moritz; Boike, Julia; Lee, Hanna; Berntsen, Terje Koren & Westermann, Sebastian (2019). Thaw processes in ice-rich permafrost landscapes represented with laterally coupled tiles in a land surface model. The Cryosphere.  ISSN 1994-0416.  13(2), s 591- 609 . doi: 10.5194/tc-13-591-2019 Full text in Research Archive.
• Angelopoulos, Michael; Westermann, Sebastian; Overduin, Paul; Faguet, Alexey; Olenchenko, Vladimir; Grosse, Guido & Grigoriev, Mikhail N (2019). Heat and Salt Flow in Subsea Permafrost Modeled with CryoGRID2. Journal of Geophysical Research (JGR): Earth Surface.  ISSN 2169-9003.  124, s 920- 937 . doi: 10.1029/2018JF004823 Full text in Research Archive.
• Czekirda, Justyna; Westermann, Sebastian; Etzelmüller, Bernd & Jóhannesson, Tómas (2019). Transient Modelling of Permafrost Distribution in Iceland. Frontiers in Earth Science.  ISSN 2296-6463.  7(130) . doi: 10.3389/feart.2019.00130 Full text in Research Archive.
• Fiddes, Joel; Aalstad, Kristoffer & Westermann, Sebastian (2019). Hyper-resolution ensemble-based snow reanalysis in mountain regions using clustering. Hydrology and Earth System Sciences.  ISSN 1027-5606.  23(11), s 4717- 4736 . doi: 10.5194/hess-23-4717-2019 Full text in Research Archive. Show summary

  Spatial variability in high-relief landscapes is immense, and grid-based models cannot be run at spatial resolutions to explicitly represent important physical processes. This hampers the assessment of the current and future evolution of important issues such as water availability or mass movement hazards. Here, we present a new processing chain that couples an efficient sub-grid method with a downscaling tool and a data assimilation method with the purpose of improving numerical simulation of surface processes at multiple spatial and temporal scales in ungauged basins. The novelty of the approach is that while we add 1–2 orders of magnitude of computational cost due to ensemble simulations, we save 4–5 orders of magnitude over explicitly simulating a high-resolution grid. This approach makes data assimilation at large spatio-temporal scales feasible. In addition, this approach utilizes only freely available global datasets and is therefore able to run globally. We demonstrate marked improvements in estimating snow height and snow water equivalent at various scales using this approach that assimilates retrievals from a MODIS snow cover product. We propose that this as a suitable method for a wide variety of operational and research applications where surface models need to be run at large scales with sparse to non-existent ground observations and with the flexibility to assimilate diverse variables retrieved by Earth observation missions.

• Karjalainen, Olli; Aalto, Juha; Luoto, Miska; Westermann, Sebastian; Romanovsky, Vladimir E; Nelson, Frederick E.; Etzelmüller, Bernd & Hjort, Jan (2019). Data Descriptor: Circumpolar permafrost maps and geohazard indices for near-future infrastructure risk assessments. Scientific Data.  ISSN 2052-4463.  6 . doi: 10.1038/sdata.2019.37 Full text in Research Archive.
• Magnin, Florence; Etzelmüller, Bernd; Westermann, Sebastian; Isaksen, Ketil; Hilger, Paula & Hermanns, Reginald (2019). Permafrost distribution in steep rock slopes in Norway: measurements, statistical modelling and implications for geomorphological processes. Earth Surface Dynamics.  ISSN 2196-6311.  7(4), s 1019- 1040 . doi: 10.5194/esurf-7-1019-2019 Full text in Research Archive.
• Martin, Leo Celestin Paul; Nitzbon, Jan; Aas, Kjetil Schanke; Etzelmüller, Bernd; Kristiansen, Håvard & Westermann, Sebastian (2019). Stability Conditions of Peat Plateaus and Palsas in Northern Norway. Journal of Geophysical Research (JGR): Earth Surface.  ISSN 2169-9003.  124(3), s 705- 719 . doi: 10.1029/2018JF004945 Full text in Research Archive.
• Myhra, Kristin Sæterdal; Westermann, Sebastian & Etzelmüller, Bernd (2019). Modelling conductive heat flow between steep rock walls and talus slopes–thermal processes and geomorphological implications. Frontiers in Earth Science.  ISSN 2296-6463.  7, s 1- 14 . doi: 10.3389/feart.2019.00192 Full text in Research Archive.
• Nitzbon, Jan; Langer, Moritz; Westermann, Sebastian; Martin, Leo Celestin Paul; Aas, Kjetil Schanke & Boike, Julia (2019). Pathways of ice-wedge degradation in polygonal tundra under different hydrological conditions. The Cryosphere.  ISSN 1994-0416.  13(4), s 1089- 1123 . doi: 10.5194/tc-13-1089-2019 Full text in Research Archive.
• Obu, Jaroslav; Westermann, Sebastian; Bartsch, Annett; Berdnikov, Nikolai M.; Christiansen, Hanne H; Dashtseren, Avirmed; Delaloye, Reynald; Elberling, Bo; Etzelmüller, Bernd; Kholodov, Alexander; Khomutov, Artem V.; Kääb, Andreas; Leibman, Marina O.; Lewkowicz, Antoni G.; Panda, Santosh K.; Romanovsky, Vladimir E.; Way, Robert G.; Westergaard-Nielsen, Andreas; Wu, Tonghua; Yamkhin, Jambaljav & Zou, Defu (2019). Northern Hemisphere permafrost map based on TTOP modelling for 2000–2016 at 1 km2 scale. Earth-Science Reviews.  ISSN 0012-8252.  193, s 299- 316 . doi: 10.1016/j.earscirev.2019.04.023 Full text in Research Archive.
• Overduin, PP; Schneider von Deimling, T; Miesner, F; Grigoriev, Mikhail N; Ruppel, Carolyn; Vasiliev, Alexander; Lantuit, H; Juhls, Bennet & Westermann, Sebastian (2019). Submarine Permafrost Map in the Arctic Modeled Using 1-D Transient Heat Flux (SuPerMAP). Journal of Geophysical Research (JGR): Oceans.  ISSN 2169-9275.  124(6), s 3490- 3507 . doi: 10.1029/2018JC014675
• Zwieback, Simon; Westermann, Sebastian; Langer, Moritz; Boike, Julia; Marsh, Philip & Berg, Aaron (2019). Improving Permafrost Modeling by Assimilating Remotely Sensed Soil Moisture. Water Resources Research.  ISSN 0043-1397.  55(3), s 1814- 1832 . doi: 10.1029/2018WR023247
• Aalstad, Kristoffer; Westermann, Sebastian; Schuler, Thomas; Boike, Julia & Bertino, Laurent (2018). Ensemble-based assimilation of fractional snow-covered area satellite retrievals to estimate the snow distribution at Arctic sites. The Cryosphere.  ISSN 1994-0416.  12(1), s 247- 270 . doi: 10.5194/tc-12-247-2018 Full text in Research Archive. Show summary

  With its high albedo, low thermal conductivity and large water storing capacity, snow strongly modulates the surface energy and water balance, which makes it a critical factor in mid- to high-latitude and mountain en- vironments. However, estimating the snow water equiva- lent (SWE) is challenging in remote-sensing applications al- ready at medium spatial resolutions of 1km. We present an ensemble-based data assimilation framework that estimates the peak subgrid SWE distribution (SSD) at the 1km scale by assimilating fractional snow-covered area (fSCA) satel- lite retrievals in a simple snow model forced by downscaled reanalysis data. The basic idea is to relate the timing of the snow cover depletion (accessible from satellite products) to the peak SSD. Peak subgrid SWE is assumed to be log- normally distributed, which can be translated to a modeled time series of fSCA through the snow model. Assimilation of satellite-derived fSCA facilitates the estimation of the peak SSD, while taking into account uncertainties in both the model and the assimilated data sets. As an extension to previ- ous studies, our method makes use of the novel (to snow data assimilation) ensemble smoother with multiple data assimi- lation (ES-MDA) scheme combined with analytical Gaussian anamorphosis to assimilate time series of Moderate Reso- lution Imaging Spectroradiometer (MODIS) and Sentinel-2 fSCA retrievals. The scheme is applied to Arctic sites near Ny-Ålesund (79◦ N, Svalbard, Norway) where field measure- ments of fSCA and SWE distributions are available. The method is able to successfully recover accurate estimates of peak SSD on most of the occasions considered. Through the ES-MDA assimilation, the root-mean-square error (RMSE) for the fSCA, peak mean SWE and peak subgrid coefficient of variation is improved by around 75, 60 and 20%, re- spectively, when compared to the prior, yielding RMSEs of 0.01, 0.09m water equivalent (w.e.) and 0.13, respectively. The ES-MDA either outperforms or at least nearly matches the performance of other ensemble-based batch smoother schemes with regards to various evaluation metrics. Given the modularity of the method, it could prove valuable for a range of satellite-era hydrometeorological reanalyses.

• Boike, Julia; Juszak, Inge; Lange, Stephan; Chadburn, Sarah; Burke, Eleanor; Paul Overduin, Pier; Roth, Kurt; Ippisch, Olaf; Bornemann, Niko; Stern, Lielle; Gouttevin, Isabelle; Hauber, Ernst & Westermann, Sebastian (2018). A 20-year record (1998-2017) of permafrost, active layer and meteorological conditions at a high Arctic permafrost research site (Bayelva, Spitsbergen). Earth System Science Data.  ISSN 1866-3508.  10(1), s 355- 390 . doi: 10.5194/essd-10-355-2018 Full text in Research Archive.
• Hjort, Jan; Karjalainen, Olli; Aalto, Juha; Westermann, Sebastian; Romanovsky, Vladimir E; Nelson, Frederick E.; Etzelmüller, Bernd & Luoto, Miska (2018). Degrading permafrost puts Arctic infrastructure at risk by mid-century. Nature Communications.  ISSN 2041-1723.  9 . doi: 10.1038/s41467-018-07557-4 Full text in Research Archive.
• Kjellman, Sofia E.; Axelsson, Pia E.; Etzelmüller, Bernd; Westermann, Sebastian & Sannel, A. Britta K. (2018). Holocene development of subarctic permafrost peatlands in Finnmark, northern Norway. The Holocene.  ISSN 0959-6836.  28(12), s 1855- 1869 . doi: 10.1177/0959683618798126 Full text in Research Archive. Show summary

  Subarctic permafrost peatlands are important soil organic carbon pools, and improved knowledge about peat properties and peatland sensitivity to past climate change is essential when predicting future response to a warmer climate and associated feedback mechanisms. In this study, Holocene peatland development and permafrost dynamics of four subarctic peat plateaus in Finnmark, northern Norway have been investigated through detailed analyses of plant macrofossils and geochemical properties. Peatland inception occurred around 9800 cal. yr BP and 9200 cal. yr BP at the two continental sites Suossjavri and Iskoras. Younger basal peat ages were found at the two coastal locations Lakselv and Karlebotn, at least partly caused by the time lag between deglaciation and emergence of land by isostatic uplift. Here, peatland development started around 6150 cal. yr BP and 5150 cal. yr BP, respectively. All four peatlands developed as wet fens throughout most of the Holocene. Permafrost aggradation, causing frost heave and a shift in the vegetation assemblage from wet fen to dry bog species, probably did not occur until during the last millennium, ca. 950 cal. yr BP in Karlebotn and ca. 800 cal. yr BP in Iskoras, and before ca. 150 cal. yr BP in Lakselv and ca. 100 cal. yr BP in Suossjavri. In Karlebotn, there are indications of a possible earlier permafrost phase around 2200 cal. yr BP due to climatic cooling at the late Subboreal to early Subatlantic transition. The mean long-term Holocene carbon accumulation rate at all four sites was 12.3 +/- 4.1 gC m-2 yr-1 (+/- SD) and the mean soil organic carbon storage was 97 +/- 46 kgC m-2.

• Strozzi, Tazio; Antonova, Sofia; Günther, Frank; Mätzler, Eva; Vieira, Gonçalo; Wegmüller, Urs; Westermann, Sebastian & Bartsch, Annett (2018). Sentinel-1 SAR interferometry for surface deformation monitoring in low-land permafrost areas. Remote Sensing.  ISSN 2072-4292.  10(9) . doi: 10.3390/rs10091360 Full text in Research Archive.
• Westergaard-Nielsen, Andreas; Karami, Mojtaba; Hansen, Birger Ulf; Westermann, Sebastian & Elberling, Bo (2018). Contrasting temperature trends across the ice-free part of Greenland. Scientific Reports.  ISSN 2045-2322.  8 . doi: 10.1038/s41598-018-19992-w Full text in Research Archive.
• Aas, Kjetil Schanke; Gisnås, Kjersti; Westermann, Sebastian & Berntsen, Terje Koren (2017). A Tiling Approach to Represent Subgrid Snow Variability in Coupled Land Surface–Atmosphere Models. Journal of Hydrometeorology.  ISSN 1525-755X.  18(1), s 49- 63 . doi: 10.1175/JHM-D-16-0026.1 Full text in Research Archive.
• Borge, Amund Frogner; Westermann, Sebastian; Solheim, Ingvild & Etzelmüller, Bernd (2017). Strong degradation of palsas and peat plateaus in northern Norway during the last 60 years. The Cryosphere.  ISSN 1994-0416.  11(1), s 1- 16 . doi: 10.5194/tc-11-1-2017 Full text in Research Archive. Show summary

  Solheim, Ingvild og Etzelmuller, Bernd er ikke (P)-personer. Fikset ms 26/9

• Chadburn, Sarah E.; Burke, Eleanor J.; Cox, Peter M.; Friedlingstein, Pierre; Hugelius, Gustaf & Westermann, Sebastian (2017). An observation-based constraint on permafrost loss as a function of global warming. Nature Climate Change.  ISSN 1758-678X.  7(5), s 340- 344 . doi: 10.1038/nclimate3262
• Chadburn, Sarah E.; Krinner, Gerhard; Porada, Philipp; Bartsch, Annett; Beer, Christian; Belelli Marchesini, Luca; Boike, Julia; Ekici, Altug; Elberling, Bo; Friborg, Thomas; Hugelius, Gustaf; Johansson, Margareta; Kuhry, Peter; Kutzbach, Lars; Langer, Moritz; Lund, Magnus; Parmentier, Frans-Jan Willem; Peng, Shushi; van Huissteden, Ko; Wang, Tao; Westermann, Sebastian; Zhu, Dan & Burke, Eleanor J. (2017). Carbon stocks and fluxes in the high latitudes: Using site-level data to evaluate Earth system models. Biogeosciences.  ISSN 1726-4170.  14(22), s 5143- 5169 . doi: 10.5194/bg-14-5143-2017 Full text in Research Archive.
• Gisnås, Kjersti; Etzelmüller, Bernd; Lussana, Cristian; Hjort, Jan; Sannel, Britta; Isaksen, Ketil; Westermann, Sebastian; Kuhry, Peter; Christiansen, Hanne H; Frampton, Andrew & Åkermann, Jonas (2017). Permafrost Map for Norway, Sweden and Finland. Permafrost and Periglacial Processes.  ISSN 1045-6740.  28(2), s 359- 378 . doi: 10.1002/ppp.1922
• Kepski, Daniel; Luks, Bartek; Migala, K.; Wawrzyniak, Tomasz; Westermann, Sebastian & Wojtun, B. (2017). Terrestrial Remote Sensing of Snowmelt in a Diverse High-Arctic Tundra Environment Using Time-Lapse Imagery. Remote Sensing.  ISSN 2072-4292.  9(7) . doi: 10.3390/rs9070733 Full text in Research Archive.
• Magnin, Florence; Westermann, Sebastian; Pogliotti, Paolo; Ravanel, Ludovico; Deline, Phillip & Malet, Eric (2017). Snow control on active layer thickness in steep alpine rock walls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif). CATENA.  ISSN 0341-8162.  149(Part 2), s 648- 662 . doi: 10.1016/j.catena.2016.06.006
• Myhra, Kristin Sæterdal; Westermann, Sebastian & Etzelmuller, Bernd (2017). Modelled Distribution and Temporal Evolution of Permafrost in Steep Rock Walls Along a Latitudinal Transect in Norway by CryoGrid 2D. Permafrost and Periglacial Processes.  ISSN 1045-6740.  28(1), s 172- 182 . doi: 10.1002/ppp.1884
• Trofaier, Anna Maria; Westermann, Sebastian & Bartsch, Annett (2017). Progress in space-borne studies of permafrost for climate science: towards a multi-ECV approach. Remote Sensing of Environment.  ISSN 0034-4257.  203, s 55- 70 . doi: 10.1016/j.rse.2017.05.021 Full text in Research Archive.
• Westermann, Sebastian; Peter, Maria; Langer, Moritz; Schwamborn, Georg; Schirrmeister, Lutz; Etzelmüller, Bernd & Boike, Julia (2017). Transient modeling of the ground thermal conditions using satellite data in the Lena River delta, Siberia. The Cryosphere.  ISSN 1994-0416.  11(3), s 1441- 1463 . doi: 10.5194/tc-11-1441-2017 Full text in Research Archive.
• Antonova, Sonya; Duguay, Claude R.; Kääb, Andreas; Heim, Birgit; Langer, Moritz; Westermann, Sebastian & Boike, Julia (2016). Monitoring ice phenology and bedfast ice in lakes of the Lena River Delta using TerraSAR-X backscatter and coherence time series. Remote Sensing.  ISSN 2072-4292.  8(11) . doi: 10.3390/rs8110903
• Bartsch, Annett; Grosse, Guido; Kääb, Andreas; Westermann, Sebastian; Strozzi, Tazio; Wiesmann, Andreas; Duguay, Claude; Seifert, Frank Martin; Obu, Jaroslav & Goler, Robert (2016). GlobPermafrost - How space-based earth observation supports understanding of permafrost. ESA SP.  ISSN 0379-6566.  SP-740
• Gisnås, Kjersti; Westermann, Sebastian; Schuler, Thomas; Melvold, Kjetil & Etzelmüller, Bernd (2016). Small-scale variation of snow in a regional permafrost model. The Cryosphere.  ISSN 1994-0416.  10(3), s 1201- 1215 . doi: 10.5194/tc-10-1201-2016
• Langer, Moritz; Westermann, Sebastian; Boike, Julia; Kirillin, Sergej; Grosse, Guido; Peng, Shushi & Krinner, Gerhard (2016). Rapid degradation of permafrost underneath waterbodies in tundra landscapes - Toward a representation of thermokarst in land surface models. Journal of Geophysical Research (JGR): Earth Surface.  ISSN 2169-9003.  121(12), s 2446- 2470 . doi: 10.1002/2016JF003956
• Steiger, Céline; Etzelmüller, Bernd; Westermann, Sebastian & Myhra, Kristin Sæterdal (2016). Modelling the permafrost distribution in steep rock walls in Norway. Norsk Geologisk Tidsskrift.  ISSN 0029-196X.  96(4), s 1- 13 . doi: 10.17850/njg96-4-04
• Wawrzyniak, Tomasz; Osuch, Marzena; Napiorkowski, Jaroslaw & Westermann, Sebastian (2016). Modelling of the thermal regime of permafrost during 1990-2014 in Hornsund, Svalbard. Polish Polar Research.  ISSN 0138-0338.  37(2), s 219- 242 . doi: 10.1515/popore-2016-0013
• Westermann, Sebastian; Langer, Moritz; Boike, Julia; Heikenfeld, Max; Peter, Maria; Etzelmuller, Bernd & Krinner, Gerhard (2016). Simulating the thermal regime and thaw processes of ice-rich permafrost ground with the land-surface model CryoGrid 3. Geoscientific Model Development.  ISSN 1991-959X.  9(2), s 523- 546 . doi: 10.5194/gmd-9-523-2016
• Aas, Kjetil Schanke; Berntsen, Terje Koren; Boike, Julia; Etzelmuller, Bernd; Kristjansson, Jon Egill; Maturilli, Marion; Schuler, Thomas; Stordal, Frode & Westermann, Sebastian (2015). A comparison between simulated and observed surface energy balance at the Svalbard Archipelago. Journal of Applied Meteorology and Climatology.  ISSN 1558-8424.  54(5), s 1102- 1119 . doi: 10.1175/JAMC-D-14-0080.1
• Gisnås, Kjersti; Westermann, Sebastian; Schuler, Thomas; Melvold, Kjetil & Etzelmuller, Bernd (2015). Small-scale variation of snow in a regional permafrost model. The Cryosphere Discussions.  ISSN 1994-0432.  9, s 6661- 6696 . doi: 10.5194/tcd-9-6661-2015
• Langer, M; Westermann, Sebastian; Walter Anthony, K.; Wischnewski, K. & Boike, J. (2015). Frozen ponds: Production and storage of methane during the Arctic winter in a lowland tundra landscape in northern Siberia, Lena River delta. Biogeosciences.  ISSN 1726-4170.  12(4), s 977- 990 . doi: 10.5194/bg-12-977-2015
• Westermann, Sebastian; Elberling, B.; Højlund Pedersen, S.; Stendel, M.; Hansen, B. U. & Liston, G.E. (2015). Future permafrost conditions along environmental gradients in Zackenberg, Greenland. The Cryosphere.  ISSN 1994-0416.  9(2), s 719- 735 . doi: 10.5194/tc-9-719-2015
• Westermann, Sebastian; Østby, Torbjørn; Gisnås, Kjersti; Schuler, Thomas & Etzelmuller, Bernd (2015). A ground temperature map of the North Atlantic permafrost region based on remote sensing and reanalysis data. The Cryosphere.  ISSN 1994-0416.  9(3), s 1303- 1319 . doi: 10.5194/tc-9-1303-2015
• Gisnås, Kjersti; Westermann, Sebastian; Schuler, Thomas; Litherland, Tobias; Isaksen, Ketil; Boike, Julia & Etzelmuller, Bernd (2014). A statistical approach to represent small-scale variability of permafrost temperatures due to snow cover. The Cryosphere Discussions.  ISSN 1994-0432.  8, s 509- 536 . doi: 10.5194/tcd-8-509-2014
• Gisnås, Kjersti; Westermann, Sebastian; Schuler, Thomas; Litherland, Tobias; Isaksen, Ketil; Boike, Julia & Etzelmuller, Bernd (2014). A statistical approach to represent small-scale variability of permafrost temperatures due to snow cover. The Cryosphere.  ISSN 1994-0416.  8, s 2063- 2074 . doi: 10.5194/tc-8-2063-2014
• Jore, Solveig; Vanwambeke, Sophie O; Viljugrein, Hildegunn; Isaksen, Ketil; Kristoffersen, Anja Bråthen; Woldehiwet, Zerai; Johansen, Bernt; Brun, Edgar; Brun-Hansen, Hege C; Westermann, Sebastian; Larsen, Inger Lise; Ytrehus, Bjørnar & Hofshagen, Merete (2014). Climate and environmental change drives Ixodes ricinus geographical expansion at the northern range margin. Parasites & Vectors.  ISSN 1756-3305.  7(1) . doi: 10.1186/1756-3305-7-11 Full text in Research Archive.
• Eberhardt, A.; Scholz, L.; Westermann, Sebastian; Sachs, T; Langer, M; Wöllenstein, J. & Palzer, S. (2014). Low cost, mobile sensor system for measurement of carbon dioxide in permafrost areas. Procedia Engineering.  ISSN 1877-7058.  87, s 1318- 1321 . doi: 10.1016/j.proeng.2014.11.690
• Hipp, Tobias Florian; Etzelmuller, Bernd & Westermann, Sebastian (2014). Permafrost in Alpine Rock Faces from Jotunheimen and Hurrungane, Southern Norway. Permafrost and Periglacial Processes.  ISSN 1045-6740.  25(1), s 1- 13 . doi: 10.1002/ppp.1799
• Langer, Moritz; Westermann, Sebastian; Walter-Anthony, Katey; Wischniewski, Karoline & Boike, Julia (2014). Frozen ponds – production and storage of methane during the Arctic winter. Biogeosciences Discussions.  ISSN 1810-6277.  11, s 11061- 11094 . doi: 10.5194/bgd-11-11061-2014
• Lüers, Johannes; Westermann, Sebastian; Piel, Konstanze & Boike, Julia (2014). Annual CO2 budget and seasonal CO2 exchange signals at a High Arctic permafrost site on Spitsbergen, Svalbard archipelago. Biogeosciences Discussions.  ISSN 1810-6277.  11, s 1535-1559 . doi: 10.5194/bgd-11-1535-2014
• Lüers, Johannes; Westermann, Sebastian; Piel, Konstanze & Boike, Julia (2014). Annual CO<sub>2</sub> budget and seasonal CO<sub>2</sub> exchange signals at a high Arctic permafrost site on Spitsbergen, Svalbard archipelago. Biogeosciences.  ISSN 1726-4170.  11(22), s 6307- 6322 . doi: 10.5194/bg-11-6307-2014
• Westermann, Sebastian; Duguay, Claude R.; Grosse, Guido & Kääb, Andreas (2014). Remote sensing of permafrost and frozen ground, In Marco Tedesco (ed.),  Remote Sensing of the Cryosphere.  John Wiley & Sons.  ISBN 9781118368855.  13.  s 307 - 344
• Westermann, Sebastian; Elberling, Bo; Pedersen, Stine; Stendel, Martin; Hansen, Birger Ulf & Liston, Glen (2014). Future permafrost conditions along environmental gradients in Zackenberg, Greenland. The Cryosphere Discussions.  ISSN 1994-0432.  8, s 3907- 3948 . doi: 10.5194/tcd-8-3907-2014
• Østby, Torbjørn; Schuler, Thomas & Westermann, Sebastian (2014). Severe cloud contamination of MODIS Land Surface Temperatures over an Arctic ice cap, Svalbard. Remote Sensing of Environment.  ISSN 0034-4257.  142, s 95- 102 . doi: 10.1016/j.rse.2013.11.005
• Boike, J.; Kattenstroth, B.; Abramova, K.; Bornemann, N.; Chetverova, A.; Fedorova, I; Fröb, K.; Grigoriev, M; Grüber, M.; Kutzbach, L.; Langer, M; Minke, M.; Muster, S.; Piel, K.; Pfeiffer, E.M.; Stoof, G.; Westermann, Sebastian; Wischnewski, K.; Wille, C. & Hubberten, H.-W. (2013). Baseline characteristics of climate, permafrost and land cover from a new permafrost observatory in the Lena River Delta, Siberia (1998-2011). Biogeosciences.  ISSN 1726-4170.  10(3), s 2105- 2128 . doi: 10.5194/bg-10-2105-2013
• Gisnås, Kjersti; Etzelmuller, Bernd; Farbrot, Herman; Schuler, Thomas & Westermann, Sebastian (2013). CryoGRID 1.0: Permafrost Distribution in Norway estimated by a Spatial Numerical Model. Permafrost and Periglacial Processes.  ISSN 1045-6740.  24(1), s 2- 19 . doi: 10.1002/ppp.1765
• Langer, Moritz; Westermann, Sebastian; Heikenfeld, Max; Dorn, Wolfgang & Boike, Julia (2013). Satellite-based modeling of permafrost temperatures in a tundra lowland landscape. Remote Sensing of Environment.  ISSN 0034-4257.  135, s 12- 24 . doi: 10.1016/j.rse.2013.03.011
• Lilleøren, Karianne Staalesen; Etzelmuller, Bernd; Gärtner-Roer, Isabelle; Kääb, Andreas; Westermann, Sebastian & Gudmundsson, Agust (2013). The Distribution, Thermal Characteristics and Dynamics of Permafrost in Tröllaskagi, Northern Iceland, as Inferred from the Distribution of Rock Glaciers and Ice-Cored Moraines. Permafrost and Periglacial Processes.  ISSN 1045-6740.  24(4), s 322- 335 . doi: 10.1002/ppp.1792
• Westermann, Sebastian; Schuler, Thomas; Gisnås, Kjersti & Etzelmuller, Bernd (2013). Transient thermal modeling of permafrost conditions in Southern Norway. The Cryosphere.  ISSN 1994-0416.  7(2), s 719- 739 . doi: 10.5194/tc-7-719-2013 Full text in Research Archive.

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• Bryn, Anders; Dalen, Thea Grobstok; Finne, Eirik Aasmo; Heiberg, Hanne; Nilsen, Irene Brox; Parmentier, Frans-Jan W.; Snekkenes, Christine; Stordal, Frode; Aas, Kjetil Schanke; Althuizen, Inge; Berntsen, Terje Koren; Bjerke, Jarle W.; Bright, Ryan M.; Dyrrdal, Anita Verpe; Geange, Sonya Rita; Pirk, Norbert; Puschmann, Oskar; Tang, Hui; Torma, Michal; Vollsnes, Ane Victoria; Westermann, Sebastian & Yilmaz, Yeliz (2020). Natur i endring.
• Bilt, Willem van der; Bakke, Jostein; Smedsrud, Lars H.; Sund, Monica; Schuler, Thomas; Westermann, Sebastian; Wong, Wai Kwok; Sandven, Stein; Simpson, Matthew James Ross; Skogen, Morten D.; Pavlova, O.; Ravndal, Ole; Risebrobakken, Bjørg; Saloranta, Tuomo; Mezghani, Abdelkader; Nilsen, Jan Even Øie; Nilsen, Irene Brox; Kierulf, Halfdan; Kohler, Jack; Melvold, Kjetil; Gjelten, Herdis Motrøen; Gundersen, Jeanette; Jaedicke, Christian; Dobler, Andreas; Engeset, Rune; Frauenfelder, Regula; Gerland, Sebastian; Christiansen, Hanne H; Børsheim, Knut Yngve; Breivik, Øyvind; Breili, Kristian; Borstad, Christopher Paul; Benestad, Rasmus; Isaksen, Ketil; Adakudlu, Muralidhar; Førland, Eirik; Hisdal, Hege; Lutz, Julia; Mayer, Stephanie; Hanssen-Bauer, Inger; Sandø, Anne Britt; Andersen, Jess; Nilsen, Frank; Sorteberg, Asgeir; Li, Hong; Bogen, Jim & Beldring, Stein (2019). Climate in Svalbard 2100. Norwegian Centre for Climate Services Reports. 1/2019. Full text in Research Archive.
• Cai, Lei; Lee, Hanna; Westermann, Sebastian & Aas, Kjetil Schanke (2019). Development of the subgrid excess ground ice framework in the Community Land Model.
• Etzelmüller, Bernd; Patton, Henry; Schomacker, Anders; Hubbard, Alun Lloyd; Czekirda, Justyna & Westermann, Sebastian (2019). Permafrost dynamics in Iceland between 18 ka BP and today – model results and geomorphological implications. Show summary

  Periglacial processes and the dynamics of permafrost is a decisive factor for slope stability locally, and for understanding landscape development over longer time scales. Iceland has a highly dynamic landscape because of young bedrock and associated high geomorphological process rates, leading to large material production and frequent gravitational processes in the present periglacial realm. At present, permafrost in Iceland is widespread in mountain settings over c. 800 m a.s.l. and sporadically in palsa mires in the central Highlands. However, during the late Pleistocene and Holocene, the periglacial environment in Iceland must have varied strongly in time and space, with subsequent imprint in the landscape. To evaluate the dynamics of permafrost in Iceland since the onset of the last deglaciation, we used the forcing and output of a 3D, time-integrated ice sheet model to run a transient permafrost model (CryoGRID 2) between the onset of the last deglaciation (c. 18 ka BP) until today. The permafrost model was forced by either modeled sub-glacial temperatures if ice-covered, or air temperatures if the area was deglaciated. The results give insights into the possible age of permafrost in Iceland, distinguish areas with wide-spread paleo-permafrost and let us determine the persistence of permafrost in the different areas. The presentation discusses these results in the light of periglacial processes, landforms and landscape development

• Christiansen, Casper Tai; Westermann, Sebastian; Risk, David & Lee, Hanna (2018). Advancing permafrost carbon climate feedback – improvements and evaluations of the Norwegian Earth System Model with observations.
• Lee, Hanna; Ekici, Altug; Robson, Benjamin Aubrey; Fan, Yuanchao; Westermann, Sebastian & Langer, Moritz (2018). Vulnerability of permafrost thaw and the emerging risks for the Arctic infrastructure.
• Aas, Kjetil Schanke; Westermann, Sebastian; Martin, Leo Celestin Paul & Berntsen, Terje Koren (2017). Degrading Palsa Mires in Northern Norway Simulated with a Regional Climate Model with a Subgrid Snow Scheme.
• Lee, Hanna; Christiansen, Casper Tai & Westermann, Sebastian (2017). Advancing permafrost carbon climate feedback – improvements and evaluations of the Norwegian Earth System Model with observations (FEEDBACK).
• Aalstad, Kristoffer; Bertino, Laurent & Westermann, Sebastian (2016). An ensemble-based subgrid snow data assimilation framework.
• Hilger, Paula; Hermanns, Reginald; Etzelmüller, Bernd; Westermann, Sebastian; Krautblatter, Michael; Gosse, John C.; Magnin, Florence & Jacobs, Benjamin (2016). Evaluation of rock-slope failures in steep permafrost slopes in Norway - first insights in the geological history of the Mannen unstable rock slope in Møre og Romsdal.
• Myhra, Kristin Sæterdal; Etzelmuller, Bernd & Westermann, Sebastian (2016). The Influence of Steep Rock Walls on the Thermal Regime of Talus Slopes.
• Nuth, Christopher; Kääb, Andreas; Westermann, Sebastian & Winsvold, Solveig Havstad (2016). Climate Change from Global Monitoring of Glaciers and Permafrost.
• Obu, Jaroslav; Westermann, Sebastian; Kääb, Andreas & Bartsch, Annett (2016). Mapping the Thermal State of Permafrost Through Modelling and Remote Sensing in ESA GlobPermafrost Project.
• Schuler, Thomas; Aalstad, Kristoffer; Aas, Kjetil Schanke; Burkhart, John; Dunse, Thorben; Filhol, Simon; Hulth, John; Østby, Torbjørn Ims & Westermann, Sebastian (2016). Towards real-time snow products for Svalbard.
• Westermann, Sebastian; Langer, Moritz; Østby, Torbjørn Ims; Peter, Maria; Boike, Julia; Gisnås, Kjersti; Aalstad, Kristoffer; Schuler, Thomas; Etzelmüller, Bernd; Jaroslav, Obu; Georg, Schwamborn & Lutz, Schirrmeister (2016). Mapping the thermal state of permafrost through modeling and remote sensing.
• Gisnås, Kjersti; Westermann, Sebastian; Etzelmuller, Bernd; Schuler, Thomas; Isaksen, Ketil; Litherland, Tobias & Boike, Julia (2014). A probabilistic approach to represent small-scale variability of permafrost temperatures due to snow cover.
• Aas, Kjetil Schanke; Berntsen, Terje Koren; Boike, Julia; Etzelmuller, Bernd; Gisnås, Kjersti & Westermann, Sebastian (2014). Simulating the surface energy balance on Svalbard with the Weather Research and Forecasting model.
• Antonova, Sonya; Langer, Moritz; Kääb, Andreas; Heim, Birgit; Boike, Julia; Bartsch, Annett & Westermann, Sebastian (2014). Spatial and temporal variability of the interferometric coherence based on TerraSAR-X imagery of the central Lena River Delta.
• Gisnås, Kjersti; Westermann, Sebastian; Schuler, Thomas & Etzelmuller, Bernd (2014). Towards Inclusion of Sub-grid Variability of Snow in Distributed Permafrost Models.
• Myhra, Kristin Sæterdal; Etzelmuller, Bernd & Westermann, Sebastian (2014). Sensitivity of Rock Slope Stability in Relation to Thermal Regime - a Study From Norway.
• Myhra, Kristin Sæterdal; Etzelmuller, Bernd & Westermann, Sebastian (2014). The Sensitivity of Rock Wall Temperatures Along a Latitudinal Transect in Norway.
• Peter, Maria; Langer, Moritz; Boike, Julia; Westermann, Sebastian & Etzelmuller, Bernd (2014). Transient permafrost modeling of the Lena River Delta, Siberia.
• Peter, Maria; Langer, Moritz; Boike, Julia; Westermann, Sebastian; Schwamborn, Georg & Etzelmuller, Bernd (2014). Modeling the regional differences in permafrost temperatures of the Lena River Delta in northern Siberia based on remote sensing products.
• Westermann, Sebastian; Boike, Julia; Etzelmuller, Bernd; Gisnås, Kjersti; Langer, Moritz; Peter, Maria; Schuler, Thomas & Østby, Torbjørn (2014). Ground temperature mapping from space.
• Westermann, Sebastian; Langer, Moritz; Peter, Maria; Boike, Julia & Etzelmuller, Bernd (2014). Large-scale monitoring of ground thermal conditions in permafrost areas using satellite-derived LST.
• Westermann, Sebastian; Langer, Moritz; Peter, Maria; Boike, Julia; Gisnås, Kjersti; Aas, Kjetil Schanke; Schuler, Thomas & Etzelmuller, Bernd (2014). Permafrost models and permafrost landscapes – is there a connection?.
• Westermann, Sebastian; Langer, Moritz; Peter, Maria; Boike, Julia; Schuler, Thomas & Etzelmuller, Bernd (2014). Large-scale monitoring of ground thermal conditions through data fusion of remote sensing products.
• Østby, Torbjørn; Westermann, Sebastian; Gisnås, Kjersti; Etzelmuller, Bernd; Schuler, Thomas & Aas, Kjetil Schanke (2014). Towards a spatial model of ground thermal regime for theSvalbard archipelago.
• Etzelmuller, Bernd; Christiansen, H.H.; Gisnås, Kjersti; Isaksen, Ketil; Schuler, Thomas & Westermann, Sebastian (2013). GROUND THERMAL REGIME AND ACTIVE LAYER THICKNESS MONITORING AND MODELLING IN THE NORDIC AREA.
• Aas, Kjetil Schanke; Berntsen, Terje Koren; Boike, Julia; Etzelmuller, Bernd; Kristjansson, Jon Egill; Schuler, Thomas; Stordal, Frode & Westermann, Sebastian (2013). Observed and simulated SEB at Ny-Ålesund, Svalbard.
• Aas, Kjetil Schanke; Berntsen, Terje Koren; Boike, Julia; Etzelmuller, Bernd; Kristjansson, Jon Egill; Schuler, Thomas; Stordal, Frode & Westermann, Sebastian (2013). Observed and simulated surface energy budget at Ny-Ålesund, Svalbard.
• Aas, Kjetil Schanke; Berntsen, Terje Koren; Boike, Julia; Etzelmuller, Bernd; Kristjansson, Jon Egill; Schuler, Thomas; Stordal, Frode & Westermann, Sebastian (2013). Observert og simulert bakke-energibalanse på Svalbard.
• Etzelmuller, Bernd; Westermann, Sebastian; Berntsen, Terje Koren; Dunse, Thorben; Gisnås, Kjersti; Hagen, Jon Ove Methlie; Kristjansson, Jon Egill; Isaksen, Ketil; Vikhamar Schuler, Dagrun; Schuler, Thomas; Stordal, Frode & Aas, Kjetil Schanke (2013). CRYOMET – Concept and Results for Bridging Models Between the Atmosphere and the Terrestrial Cryosphere (Glacier and Permafrost).
• Etzelmuller, Bernd; Westermann, Sebastian; Berntsen, Terje Koren; Gisnås, Kjersti; Hagen, Jon Ove Methlie; Kristjansson, Jon Egill; Schuler, Thomas; Vikhamar Schuler, Dagrun; Stordal, Frode & Aas, Kjetil Schanke (2013). Bridging models for the terrestrial cryosphere and the atmosphere - The CryoMET project.
• Gisnås, Kjersti; Westermann, Sebastian; Etzelmuller, Bernd & Schuler, Thomas (2013). From Snow Depth Distribution to Small-Scale Variability of Soil Temperatures.
• Westermann, Sebastian; Berntsen, Terje; Etzelmuller, Bernd; Gisnås, Kjersti; Hagen, Jon Ove Methlie; Kristjansson, Jon Egill; Schuler, Thomas & Stordal, Frode (2013). The CryoMet project - combining deterministic and probabilistic downscaling to model snow depth over a wide range of scales.
• Westermann, Sebastian & Etzelmuller, Bernd (2013). Permafrost thawing and increased winter discharge in Northern Norway – is there a connection?.
• Westermann, Sebastian; Langer, Moritz; Heikenfeld, Max & Boike, Julia (2013). CryoGrid 3 – a new flexible tool for permafrost modeling.
• Østby, Torbjørn; Schuler, Thomas & Westermann, Sebastian (2013). Quality assessment of MODIS land surface temperatures over an Arctic ice cap.
• Østby, Torbjørn; Schuler, Thomas & Westermann, Sebastian (2013). Quality assessment of MODIS land surface temperatures over an Arctic ice cap,Svalbard.
• Østby, Torbjørn; Schuler, Thomas & Westermann, Sebastian (2013). Use of satellite-derived land surface temperatures over Svalbard glaciers.

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