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- Oehri, Jacqueline, et al.
(författare)
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Vegetation type is an important predictor of the arctic summer land surface energy budget
- 2022
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Despite the importance of high-latitude surface energy budgets (SEBs) for land-climate interactions in the rapidly changing Arctic, uncertainties in their prediction persist. Here, we harmonize SEB observations across a network of vegetated and glaciated sites at circumpolar scale (1994–2021). Our variance-partitioning analysis identifies vegetation type as an important predictor for SEB-components during Arctic summer (June-August), compared to other SEB-drivers including climate, latitude and permafrost characteristics. Differences among vegetation types can be of similar magnitude as between vegetation and glacier surfaces and are especially high for summer sensible and latent heat fluxes. The timing of SEB-flux summer-regimes (when daily mean values exceed 0 Wm−2) relative to snow-free and -onset dates varies substantially depending on vegetation type, implying vegetation controls on snow-cover and SEB-flux seasonality. Our results indicate complex shifts in surface energy fluxes with land-cover transitions and a lengthening summer season, and highlight the potential for improving future Earth system models via a refined representation of Arctic vegetation types.
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| 2. |
- Beckebanze, Lutz, et al.
(författare)
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Lateral carbon export has low impact on the net ecosystem carbon balance of a polygonal tundra catchment
- 2022
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Ingår i: Biogeosciences. - : Copernicus Publications. - 1726-4170 .- 1726-4189. ; 19:16, s. 3863-3876
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Tidskriftsartikel (refereegranskat)abstract
- Permafrost-affected soils contain large quantities of soil organic carbon (SOC). Changes in the SOC pool of a particular ecosystem can be related to its net ecosystem carbon balance (NECB) in which the balance of carbon (C) influxes and effluxes is expressed. For polygonal tundra landscapes, accounts of ecosystem carbon balances in the literature are often solely based on estimates of vertical carbon fluxes. To fill this gap, we present data regarding the lateral export rates of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) from a polygonal tundra site in the north Siberian Lena River delta, Russia. We use water discharge observations in combination with concentration measurements of waterborne carbon to derive the lateral carbon fluxes from one growing season (2 June–8 September 2014 for DOC, 8 June–8 September 2014 for DIC). To put the lateral C fluxes into context, we furthermore present the surface–atmosphere eddy covariance fluxes of carbon dioxide (CO2) and methane (CH4) from this study site. The results show cumulative lateral DIC and DOC fluxes of 0.31–0.38 and 0.06–0.08 g m−2, respectively, during the 93 d observation period (8 June–8 September 2014). Vertical turbulent fluxes of CO2-C and CH4-C accumulated to −19.0 ± 1.2 and 1.0 ± 0.02 g m−2 in the same period. Thus, the lateral C export represented about 2 % of the net ecosystem exchange of (NEE) CO2. However, the relationship between lateral and surface–atmosphere fluxes changed over the observation period. At the beginning of the growing season (early June), the lateral C flux outpaced the surface-directed net vertical turbulent CO2 flux, causing the polygonal tundra landscape to be a net carbon source during this time of the year. Later in the growing season, the vertical turbulent CO2 flux dominated the NECB.
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