Jaroslav Obu

• Alexander, Andreas; Obu, Jaroslav; Schuler, Thomas; Kääb, Andreas & Christiansen, Hanne H (2020). Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard. The Cryosphere.  ISSN 1994-0416.  14(11), s 4217- 4231 . doi: 10.5194/tc-14-4217-2020 Fulltekst i vitenarkiv.
• Alexander, Andreas; Obu, Jaroslav; Schuler, Thomas; Kääb, Andreas & Christiansen, Hanne H (2020). Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard. The Cryosphere Discussions.  ISSN 1994-0432. . doi: https://doi.org/10.5194/tc-2020-124
• Obu, Jaroslav; Westermann, Sebastian; Vieira, Gonçalo; Abramov, Andrey; Balks, Megan Ruby; Bartsch, Annett; Hrbáček, Filip; Kääb, Andreas & Ramos, Miguel (2020). Pan-Antarctic map of near-surface permafrost temperatures at 1 km2 scale. The Cryosphere.  ISSN 1994-0416.  14(2), s 497- 519 . doi: 10.5194/tc-14-497-2020 Fulltekst i vitenarkiv. Vis sammendrag

  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.

• 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 Fulltekst i vitenarkiv.
• Obu, Jaroslav; Košutnik, Jure; Overduin, Paul; Boike, Julia; Blatnik, Matej; Zwieback, Simon; Gostinčar, Petra & Mihevc, Andrej (2018). Sorted patterned ground in a karst cave, Ledenica pod Hrušico, Slovenia. Permafrost and Periglacial Processes.  ISSN 1045-6740.  29(2), s 121- 130 . doi: 10.1002/ppp.1970 Vis sammendrag

  Patterned ground is a characteristic periglacial landform in polar and alpine environments but has not been systematically studied in karst caves. Here we characterize the periglacial environment and sorted stripes within the Ledenica pod Hrušico ice cave, western Slovenia. The stripes were mapped, sediment depth and grain size were measured, and cave and outside air temperatures were monitored together with ground temperatures. Eleven sorted stripes of coarse limestone debris had developed on 1 m thick silt-rich sediment, underlain by limestone bedrock. Silt-rich cave sediments can accumulate as insoluble carbonate residue or during flood events, whereas coarse debris may result from frost shattering. Cold winter air entered the ice cave, but little air exchange occurred during summer, when the cave air temperature slowly rose to a maximum of 5°C. Winter temperature oscillations propagated efficiently to the snow-free cave floor. Fourteen freeze-thaw cycles were observed at the patterned-ground surface during winter 2015/2016 and may cause the differential frost heaving necessary for sediment sorting. Such periglacial conditions and mixtures of silty and coarse sediments can produce sorted

• 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
• Obu, Jaroslav; Lantuit, Hugues; Fritz, Michael; Pollard, Wayne H.; Sachs, Torsten & Günther, Frank (2016). Relation between planimetric and volumetric measurements of permafrost coast erosion : a case study from Herschel Island, Western Canadian Arctic. Polar Research.  ISSN 0800-0395.  35(1) . doi: 10.3402/polar.v35.30313

Se alle arbeider i Cristin

• Alexander, Andreas; Obu, Jaroslav; Schuler, Thomas; Kääb, Andreas & Christiansen, Hanne H (2020). Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard.
• Obu, Jaroslav; Westermann, Sebastian; Kääb, Andreas & Bartsch, Annett (2016). Mapping the Thermal State of Permafrost Through Modelling and Remote Sensing in ESA GlobPermafrost Project.

Se alle arbeider i Cristin