Explicitly modelling microtopography in permafrost landscapes in a land surface model (JULES vn5.4_microtopography)
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 of abrupt thaw processes. Here we have implemented a two-tile representation of...
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Copernicus Publications
2022
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ftdoajarticles:oai:doaj.org/article:a6e8aac86c2c4f29b47476270950feb5 2023-05-15T17:54:26+02:00 Explicitly modelling microtopography in permafrost landscapes in a land surface model (JULES vn5.4_microtopography) N. D. Smith E. J. Burke K. Schanke Aas I. H. J. Althuizen J. Boike C. T. Christiansen B. Etzelmüller T. Friborg H. Lee H. Rumbold R. H. Turton S. Westermann S. E. Chadburn 2022-05-01T00:00:00Z https://doi.org/10.5194/gmd-15-3603-2022 https://doaj.org/article/a6e8aac86c2c4f29b47476270950feb5 EN eng Copernicus Publications https://gmd.copernicus.org/articles/15/3603/2022/gmd-15-3603-2022.pdf https://doaj.org/toc/1991-959X https://doaj.org/toc/1991-9603 doi:10.5194/gmd-15-3603-2022 1991-959X 1991-9603 https://doaj.org/article/a6e8aac86c2c4f29b47476270950feb5 Geoscientific Model Development, Vol 15, Pp 3603-3639 (2022) Geology QE1-996.5 article 2022 ftdoajarticles https://doi.org/10.5194/gmd-15-3603-2022 2022-12-31T00:09:45Z 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 of abrupt thaw processes. Here we have implemented a two-tile representation of microtopography in JULES (the Joint UK Land Environment Simulator), where tiles are representative of repeating patterns of elevation difference. Tiles are coupled by lateral flows of water, heat, and redistribution of snow, and a surface water store is added to represent ponding. Simulations are performed of two Siberian polygon sites, (Samoylov and Kytalyk) and two Scandinavian palsa sites (Stordalen and Iškoras). The model represents the observed differences between greater snow depth in hollows vs. raised areas well. The model also improves soil moisture for hollows vs. the non-tiled configuration (“standard JULES”) though the raised tile remains drier than observed. The modelled differences in snow depths and soil moisture between tiles result in the lower tile soil temperatures being warmer for palsa sites, as in reality. However, when comparing the soil temperatures for July at 20 cm depth, the difference in temperature between tiles, or “temperature splitting”, is smaller than observed (3.2 vs. 5.5 ∘ C). Polygons display small (0.2 ∘ C) to zero temperature splitting, in agreement with observations. Consequently, methane fluxes are near identical ( + 0 % to 9 %) to those for standard JULES for polygons, although they can be greater than standard JULES for palsa sites ( + 10 % to 49 %). Through a sensitivity analysis we quantify the relative importance of model processes with respect to soil moisture and temperatures, identifying which parameters result in the greatest uncertainty in modelled temperature. Varying the palsa elevation between 0.5 and 3 m has little effect on modelled soil temperatures, showing that using only two tiles can still be a valid representation of sites with a range of palsa elevations. ... Article in Journal/Newspaper palsa permafrost Directory of Open Access Journals: DOAJ Articles Iškoras ENVELOPE(25.369,25.369,69.297,69.297) Jules ENVELOPE(140.917,140.917,-66.742,-66.742) Stordalen ENVELOPE(7.337,7.337,62.510,62.510) Geoscientific Model Development 15 9 3603 3639 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geology QE1-996.5 |
spellingShingle |
Geology QE1-996.5 N. D. Smith E. J. Burke K. Schanke Aas I. H. J. Althuizen J. Boike C. T. Christiansen B. Etzelmüller T. Friborg H. Lee H. Rumbold R. H. Turton S. Westermann S. E. Chadburn Explicitly modelling microtopography in permafrost landscapes in a land surface model (JULES vn5.4_microtopography) |
topic_facet |
Geology QE1-996.5 |
description |
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 of abrupt thaw processes. Here we have implemented a two-tile representation of microtopography in JULES (the Joint UK Land Environment Simulator), where tiles are representative of repeating patterns of elevation difference. Tiles are coupled by lateral flows of water, heat, and redistribution of snow, and a surface water store is added to represent ponding. Simulations are performed of two Siberian polygon sites, (Samoylov and Kytalyk) and two Scandinavian palsa sites (Stordalen and Iškoras). The model represents the observed differences between greater snow depth in hollows vs. raised areas well. The model also improves soil moisture for hollows vs. the non-tiled configuration (“standard JULES”) though the raised tile remains drier than observed. The modelled differences in snow depths and soil moisture between tiles result in the lower tile soil temperatures being warmer for palsa sites, as in reality. However, when comparing the soil temperatures for July at 20 cm depth, the difference in temperature between tiles, or “temperature splitting”, is smaller than observed (3.2 vs. 5.5 ∘ C). Polygons display small (0.2 ∘ C) to zero temperature splitting, in agreement with observations. Consequently, methane fluxes are near identical ( + 0 % to 9 %) to those for standard JULES for polygons, although they can be greater than standard JULES for palsa sites ( + 10 % to 49 %). Through a sensitivity analysis we quantify the relative importance of model processes with respect to soil moisture and temperatures, identifying which parameters result in the greatest uncertainty in modelled temperature. Varying the palsa elevation between 0.5 and 3 m has little effect on modelled soil temperatures, showing that using only two tiles can still be a valid representation of sites with a range of palsa elevations. ... |
format |
Article in Journal/Newspaper |
author |
N. D. Smith E. J. Burke K. Schanke Aas I. H. J. Althuizen J. Boike C. T. Christiansen B. Etzelmüller T. Friborg H. Lee H. Rumbold R. H. Turton S. Westermann S. E. Chadburn |
author_facet |
N. D. Smith E. J. Burke K. Schanke Aas I. H. J. Althuizen J. Boike C. T. Christiansen B. Etzelmüller T. Friborg H. Lee H. Rumbold R. H. Turton S. Westermann S. E. Chadburn |
author_sort |
N. D. Smith |
title |
Explicitly modelling microtopography in permafrost landscapes in a land surface model (JULES vn5.4_microtopography) |
title_short |
Explicitly modelling microtopography in permafrost landscapes in a land surface model (JULES vn5.4_microtopography) |
title_full |
Explicitly modelling microtopography in permafrost landscapes in a land surface model (JULES vn5.4_microtopography) |
title_fullStr |
Explicitly modelling microtopography in permafrost landscapes in a land surface model (JULES vn5.4_microtopography) |
title_full_unstemmed |
Explicitly modelling microtopography in permafrost landscapes in a land surface model (JULES vn5.4_microtopography) |
title_sort |
explicitly modelling microtopography in permafrost landscapes in a land surface model (jules vn5.4_microtopography) |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/gmd-15-3603-2022 https://doaj.org/article/a6e8aac86c2c4f29b47476270950feb5 |
long_lat |
ENVELOPE(25.369,25.369,69.297,69.297) ENVELOPE(140.917,140.917,-66.742,-66.742) ENVELOPE(7.337,7.337,62.510,62.510) |
geographic |
Iškoras Jules Stordalen |
geographic_facet |
Iškoras Jules Stordalen |
genre |
palsa permafrost |
genre_facet |
palsa permafrost |
op_source |
Geoscientific Model Development, Vol 15, Pp 3603-3639 (2022) |
op_relation |
https://gmd.copernicus.org/articles/15/3603/2022/gmd-15-3603-2022.pdf https://doaj.org/toc/1991-959X https://doaj.org/toc/1991-9603 doi:10.5194/gmd-15-3603-2022 1991-959X 1991-9603 https://doaj.org/article/a6e8aac86c2c4f29b47476270950feb5 |
op_doi |
https://doi.org/10.5194/gmd-15-3603-2022 |
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Geoscientific Model Development |
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15 |
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9 |
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3603 |
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3639 |
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