Spatial variability of CO 2 uptake in polygonal tundra: assessing low-frequency disturbances in eddy covariance flux estimates
The large spatial variability in Arctic tundra complicates the representative assessment of CO 2 budgets. Accurate measurements of these heterogeneous landscapes are, however, essential to understanding their vulnerability to climate change. We surveyed a polygonal tundra lowland on Svalbard with an...
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ftzenodo:oai:zenodo.org:820817 2024-09-15T18:02:26+00:00 Spatial variability of CO 2 uptake in polygonal tundra: assessing low-frequency disturbances in eddy covariance flux estimates Pirk, N. Sievers, J. Mertes, J. Parmentier, F.-J. W. Mastepanov, M. Christensen, T. R. 2017-06-29 https://doi.org/10.5194/bg-14-3157-2017 unknown Zenodo https://zenodo.org/communities/eu https://doi.org/10.5194/bg-14-3157-2017 oai:zenodo.org:820817 info:eu-repo/semantics/openAccess Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/legalcode Biogeosciences, 14(12), 3157-3169, (2017-06-29) info:eu-repo/semantics/article 2017 ftzenodo https://doi.org/10.5194/bg-14-3157-2017 2024-07-26T01:22:24Z The large spatial variability in Arctic tundra complicates the representative assessment of CO 2 budgets. Accurate measurements of these heterogeneous landscapes are, however, essential to understanding their vulnerability to climate change. We surveyed a polygonal tundra lowland on Svalbard with an unmanned aerial vehicle (UAV) that mapped ice-wedge morphology to complement eddy covariance (EC) flux measurements of CO 2 . The analysis of spectral distributions showed that conventional EC methods do not accurately capture the turbulent CO 2 exchange with a spatially heterogeneous surface that typically features small flux magnitudes. Nonlocal (low-frequency) flux contributions were especially pronounced during snowmelt and introduced a large bias of −46 gC m −2 to the annual CO 2 budget in conventional methods (the minus sign indicates a higher uptake by the ecosystem). Our improved flux calculations with the ogive optimization method indicated that the site was a strong sink for CO 2 in 2015 (−82 gC m −2 ). Due to differences in light-use efficiency, wetter areas with low-centered polygons sequestered 47 % more CO 2 than drier areas with flat-centered polygons. While Svalbard has experienced a strong increase in mean annual air temperature of more than 2 K in the last few decades, historical aerial photographs from the site indicated stable ice-wedge morphology over the last 7 decades. Apparently, warming has thus far not been sufficient to initiate strong ice-wedge degradation, possibly due to the absence of extreme heat episodes in the maritime climate on Svalbard. However, in Arctic regions where ice-wedge degradation has already initiated the associated drying of landscapes, our results suggest a weakening of the CO 2 sink in polygonal tundra. Article in Journal/Newspaper Climate change Svalbard Tundra Zenodo Biogeosciences 14 12 3157 3169 |
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The large spatial variability in Arctic tundra complicates the representative assessment of CO 2 budgets. Accurate measurements of these heterogeneous landscapes are, however, essential to understanding their vulnerability to climate change. We surveyed a polygonal tundra lowland on Svalbard with an unmanned aerial vehicle (UAV) that mapped ice-wedge morphology to complement eddy covariance (EC) flux measurements of CO 2 . The analysis of spectral distributions showed that conventional EC methods do not accurately capture the turbulent CO 2 exchange with a spatially heterogeneous surface that typically features small flux magnitudes. Nonlocal (low-frequency) flux contributions were especially pronounced during snowmelt and introduced a large bias of −46 gC m −2 to the annual CO 2 budget in conventional methods (the minus sign indicates a higher uptake by the ecosystem). Our improved flux calculations with the ogive optimization method indicated that the site was a strong sink for CO 2 in 2015 (−82 gC m −2 ). Due to differences in light-use efficiency, wetter areas with low-centered polygons sequestered 47 % more CO 2 than drier areas with flat-centered polygons. While Svalbard has experienced a strong increase in mean annual air temperature of more than 2 K in the last few decades, historical aerial photographs from the site indicated stable ice-wedge morphology over the last 7 decades. Apparently, warming has thus far not been sufficient to initiate strong ice-wedge degradation, possibly due to the absence of extreme heat episodes in the maritime climate on Svalbard. However, in Arctic regions where ice-wedge degradation has already initiated the associated drying of landscapes, our results suggest a weakening of the CO 2 sink in polygonal tundra. |
format |
Article in Journal/Newspaper |
author |
Pirk, N. Sievers, J. Mertes, J. Parmentier, F.-J. W. Mastepanov, M. Christensen, T. R. |
spellingShingle |
Pirk, N. Sievers, J. Mertes, J. Parmentier, F.-J. W. Mastepanov, M. Christensen, T. R. Spatial variability of CO 2 uptake in polygonal tundra: assessing low-frequency disturbances in eddy covariance flux estimates |
author_facet |
Pirk, N. Sievers, J. Mertes, J. Parmentier, F.-J. W. Mastepanov, M. Christensen, T. R. |
author_sort |
Pirk, N. |
title |
Spatial variability of CO 2 uptake in polygonal tundra: assessing low-frequency disturbances in eddy covariance flux estimates |
title_short |
Spatial variability of CO 2 uptake in polygonal tundra: assessing low-frequency disturbances in eddy covariance flux estimates |
title_full |
Spatial variability of CO 2 uptake in polygonal tundra: assessing low-frequency disturbances in eddy covariance flux estimates |
title_fullStr |
Spatial variability of CO 2 uptake in polygonal tundra: assessing low-frequency disturbances in eddy covariance flux estimates |
title_full_unstemmed |
Spatial variability of CO 2 uptake in polygonal tundra: assessing low-frequency disturbances in eddy covariance flux estimates |
title_sort |
spatial variability of co 2 uptake in polygonal tundra: assessing low-frequency disturbances in eddy covariance flux estimates |
publisher |
Zenodo |
publishDate |
2017 |
url |
https://doi.org/10.5194/bg-14-3157-2017 |
genre |
Climate change Svalbard Tundra |
genre_facet |
Climate change Svalbard Tundra |
op_source |
Biogeosciences, 14(12), 3157-3169, (2017-06-29) |
op_relation |
https://zenodo.org/communities/eu https://doi.org/10.5194/bg-14-3157-2017 oai:zenodo.org:820817 |
op_rights |
info:eu-repo/semantics/openAccess Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/legalcode |
op_doi |
https://doi.org/10.5194/bg-14-3157-2017 |
container_title |
Biogeosciences |
container_volume |
14 |
container_issue |
12 |
container_start_page |
3157 |
op_container_end_page |
3169 |
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1810439895313809408 |