Investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model
The contribution of soil heterotrophic respiration to the boreal–Arctic carbon (CO 2 ) cycle and its potential feedback to climate change remains poorly quantified. We developed a remote-sensing-driven permafrost carbon model at intermediate scale ( ∼1 km) to investigate how environmental factors af...
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ftcopernicus:oai:publications.copernicus.org:bg85819 2023-05-15T15:08:00+02:00 Investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model Yi, Yonghong Kimball, John S. Watts, Jennifer D. Natali, Susan M. Zona, Donatella Liu, Junjie Ueyama, Masahito Kobayashi, Hideki Oechel, Walter Miller, Charles E. 2020-11-27 application/pdf https://doi.org/10.5194/bg-17-5861-2020 https://bg.copernicus.org/articles/17/5861/2020/ eng eng doi:10.5194/bg-17-5861-2020 https://bg.copernicus.org/articles/17/5861/2020/ eISSN: 1726-4189 Text 2020 ftcopernicus https://doi.org/10.5194/bg-17-5861-2020 2020-11-30T17:22:13Z The contribution of soil heterotrophic respiration to the boreal–Arctic carbon (CO 2 ) cycle and its potential feedback to climate change remains poorly quantified. We developed a remote-sensing-driven permafrost carbon model at intermediate scale ( ∼1 km) to investigate how environmental factors affect the magnitude and seasonality of soil heterotrophic respiration in Alaska. The permafrost carbon model simulates snow and soil thermal dynamics and accounts for vertical soil carbon transport and decomposition at depths up to 3 m below the surface. Model outputs include soil temperature profiles and carbon fluxes at 1 km resolution spanning the recent satellite era (2001–2017) across Alaska. Comparisons with eddy covariance tower measurements show that the model captures the seasonality of carbon fluxes, with favorable accuracy in simulating net ecosystem CO 2 exchange (NEE) for both tundra ( R >0.8 , root mean square error (RMSE – 0.34 g C m −2 d −1 ), and boreal forest ( R >0.73 RMSE – 0.51 g C m −2 d −1 ). Benchmark assessments using two regional in situ data sets indicate that the model captures the complex influence of snow insulation on soil temperature and the temperature sensitivity of cold-season soil heterotrophic respiration. Across Alaska, we find that seasonal snow cover imposes strong controls on the contribution from different soil depths to total soil heterotrophic respiration. Earlier snowmelt in spring promotes deeper soil warming and enhances the contribution of deeper soils to total soil heterotrophic respiration during the later growing season, thereby reducing net ecosystem carbon uptake. Early cold-season soil heterotrophic respiration is closely linked to the number of snow-free days after the land surface freezes ( <math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi>R</mi><mo>=</mo><mo>-</mo><mn mathvariant="normal">0.48</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="76fd517b270f8d3ae2d9113b282b58b4"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-17-5861-2020-ie00001.svg" width="52pt" height="10pt" src="bg-17-5861-2020-ie00001.png"/></svg:svg> , p <0.1 ), i.e., the delay in snow onset relative to surface freeze onset. Recent trends toward earlier autumn snow onset in northern Alaska promote a longer zero-curtain period and enhanced cold-season respiration. In contrast, southwestern Alaska shows a strong reduction in the number of snow-free days after land surface freeze onset, leading to earlier soil freezing and a large reduction in cold-season soil heterotrophic respiration. Our results also show nonnegligible influences of subgrid variability in surface conditions on the model-simulated CO 2 seasonal cycle, especially during the early cold season at 10 km scale. Our results demonstrate the critical role of snow cover affecting the seasonality of soil temperature and respiration and highlight the challenges of incorporating these complex processes into future projections of the boreal–Arctic carbon cycle. Text Arctic Climate change permafrost Tundra Alaska Copernicus Publications: E-Journals Arctic Biogeosciences 17 22 5861 5882 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
The contribution of soil heterotrophic respiration to the boreal–Arctic carbon (CO 2 ) cycle and its potential feedback to climate change remains poorly quantified. We developed a remote-sensing-driven permafrost carbon model at intermediate scale ( ∼1 km) to investigate how environmental factors affect the magnitude and seasonality of soil heterotrophic respiration in Alaska. The permafrost carbon model simulates snow and soil thermal dynamics and accounts for vertical soil carbon transport and decomposition at depths up to 3 m below the surface. Model outputs include soil temperature profiles and carbon fluxes at 1 km resolution spanning the recent satellite era (2001–2017) across Alaska. Comparisons with eddy covariance tower measurements show that the model captures the seasonality of carbon fluxes, with favorable accuracy in simulating net ecosystem CO 2 exchange (NEE) for both tundra ( R >0.8 , root mean square error (RMSE – 0.34 g C m −2 d −1 ), and boreal forest ( R >0.73 RMSE – 0.51 g C m −2 d −1 ). Benchmark assessments using two regional in situ data sets indicate that the model captures the complex influence of snow insulation on soil temperature and the temperature sensitivity of cold-season soil heterotrophic respiration. Across Alaska, we find that seasonal snow cover imposes strong controls on the contribution from different soil depths to total soil heterotrophic respiration. Earlier snowmelt in spring promotes deeper soil warming and enhances the contribution of deeper soils to total soil heterotrophic respiration during the later growing season, thereby reducing net ecosystem carbon uptake. Early cold-season soil heterotrophic respiration is closely linked to the number of snow-free days after the land surface freezes ( <math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi>R</mi><mo>=</mo><mo>-</mo><mn mathvariant="normal">0.48</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="76fd517b270f8d3ae2d9113b282b58b4"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-17-5861-2020-ie00001.svg" width="52pt" height="10pt" src="bg-17-5861-2020-ie00001.png"/></svg:svg> , p <0.1 ), i.e., the delay in snow onset relative to surface freeze onset. Recent trends toward earlier autumn snow onset in northern Alaska promote a longer zero-curtain period and enhanced cold-season respiration. In contrast, southwestern Alaska shows a strong reduction in the number of snow-free days after land surface freeze onset, leading to earlier soil freezing and a large reduction in cold-season soil heterotrophic respiration. Our results also show nonnegligible influences of subgrid variability in surface conditions on the model-simulated CO 2 seasonal cycle, especially during the early cold season at 10 km scale. Our results demonstrate the critical role of snow cover affecting the seasonality of soil temperature and respiration and highlight the challenges of incorporating these complex processes into future projections of the boreal–Arctic carbon cycle. |
format |
Text |
author |
Yi, Yonghong Kimball, John S. Watts, Jennifer D. Natali, Susan M. Zona, Donatella Liu, Junjie Ueyama, Masahito Kobayashi, Hideki Oechel, Walter Miller, Charles E. |
spellingShingle |
Yi, Yonghong Kimball, John S. Watts, Jennifer D. Natali, Susan M. Zona, Donatella Liu, Junjie Ueyama, Masahito Kobayashi, Hideki Oechel, Walter Miller, Charles E. Investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model |
author_facet |
Yi, Yonghong Kimball, John S. Watts, Jennifer D. Natali, Susan M. Zona, Donatella Liu, Junjie Ueyama, Masahito Kobayashi, Hideki Oechel, Walter Miller, Charles E. |
author_sort |
Yi, Yonghong |
title |
Investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model |
title_short |
Investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model |
title_full |
Investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model |
title_fullStr |
Investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model |
title_full_unstemmed |
Investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model |
title_sort |
investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in alaska using a satellite-based permafrost carbon model |
publishDate |
2020 |
url |
https://doi.org/10.5194/bg-17-5861-2020 https://bg.copernicus.org/articles/17/5861/2020/ |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Climate change permafrost Tundra Alaska |
genre_facet |
Arctic Climate change permafrost Tundra Alaska |
op_source |
eISSN: 1726-4189 |
op_relation |
doi:10.5194/bg-17-5861-2020 https://bg.copernicus.org/articles/17/5861/2020/ |
op_doi |
https://doi.org/10.5194/bg-17-5861-2020 |
container_title |
Biogeosciences |
container_volume |
17 |
container_issue |
22 |
container_start_page |
5861 |
op_container_end_page |
5882 |
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1766339429878726656 |