Improved ELMv1-ECA simulations of zero-curtain periods and cold-season CH<sub>4</sub> and CO<sub>2</sub> emissions at Alaskan Arctic tundra sites
<p>Field measurements have shown that cold-season methane (CH<span class="inline-formula"><sub>4</sub></span>) and carbon dioxide (CO<span class="inline-formula"><sub>2</sub></span>) emissions contribute a substantial portion...
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| Autores principales: | , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Copernicus Publications
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/df538f9e88824470b5af2f4a6e5dc673 |
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| Sumario: | <p>Field measurements have shown that cold-season methane
(CH<span class="inline-formula"><sub>4</sub></span>) and carbon dioxide (CO<span class="inline-formula"><sub>2</sub></span>) emissions contribute a substantial
portion to the annual net carbon emissions in permafrost regions. However,
most earth system land models do not accurately reproduce cold-season
CH<span class="inline-formula"><sub>4</sub></span> and CO<span class="inline-formula"><sub>2</sub></span> emissions, especially over the shoulder (i.e., thawing
and freezing) seasons. Here we use the Energy Exascale Earth System Model
(E3SM) land model version 1 (ELMv1-ECA) to tackle this challenge and fill
the knowledge gap of how cold-season CH<span class="inline-formula"><sub>4</sub></span> and CO<span class="inline-formula"><sub>2</sub></span> emissions
contribute to the annual totals at Alaska Arctic tundra sites. Specifically,
we improved the ELMv1-ECA soil water phase-change scheme, environmental
controls on microbial activity, and the methane module. Results demonstrate that both soil temperature and the duration of
zero-curtain periods (i.e., the fall period when soil temperatures linger
around 0 <span class="inline-formula"><sup>∘</sup></span>C) simulated by the updated ELMv1-ECA were greatly
improved; e.g., the mean absolute error (MAE) in zero-curtain durations at
12 cm depth was reduced by 62 % on average. Furthermore, the MAEs of
simulated cold-season carbon emissions at three tundra sites were improved
by 72 % and 70 % on average for CH<span class="inline-formula"><sub>4</sub></span> and CO<span class="inline-formula"><sub>2</sub></span>, respectively.
Overall, CH<span class="inline-formula"><sub>4</sub></span> emitted during the early cold season (September and October),
which often includes most of the zero-curtain period in Arctic tundra,
accounted for more than 50 % of the total emissions throughout the entire
cold season (September to May) in the model, compared with around 49.4 %
(43 %–58 %) in observations. From 1950 to 2017, both CO<span class="inline-formula"><sub>2</sub></span> emissions
during the zero-curtain period and during the entire cold season showed
increasing trends, for example, of 0.17 and 0.36 gC m<span class="inline-formula"><sup>−2</sup></span> yr<span class="inline-formula"><sup>−1</sup></span> at Atqasuk. This study highlights the importance of
zero-curtain periods in facilitating cold-season CH<span class="inline-formula"><sub>4</sub></span> and CO<span class="inline-formula"><sub>2</sub></span> emissions from
tundra ecosystems.</p> |
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