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Sensible Heat and Latent Heat Flux Estimates in a Tall and Dense Forest Canopy under Unstable Conditions. ATMOSPHERE 2022. [DOI: 10.3390/atmos13020264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A method to estimate the sensible heat flux (H) for unstable atmospheric condition requiring measurements taken in half-hourly basis as input and involving the land surface temperature (LST), HLST, was tested over a tall and dense aspen stand. The method avoids the need to estimate the zero-plane displacement and the roughness length for momentum. The net radiation (Rn) and the latent heat flux (λE) dominated the surface energy balance (SEB). Therefore, λE was estimated applying the residual method using HLST as input, λER-LST. The sum of H and λE determined with the eddy covariance (EC) method led to a surface energy imbalance of 20% Rn. Thus, the reference taken for the comparisons were determined forcing the SEB using the EC Bowen ratio (BREB method). For clear sky days, HLST performed close to HBREB. Therefore, it showed potential in the framework of remote sensing because the input requirements are similar to current methods widely used. For cloudy days, HLST scattered HBREB and nearly matched the accumulated sensible hear flux. Regardless of the time basis and cloudiness, λER-LST was close to λEBREB. For all the data, both HLST and λER-LST were not biased and showed, respectively, a mean absolute relative error of 24.5% and 12.5% and an index of agreement of 68.5% and 80%.
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Abstract
The parallelized large-eddy simulation model (PALM) was used to understand better the turbulent exchanges of a passive scalar above and within a forested region located in the central Amazon. Weak (2 ms−1) and strong (6 ms−1) wind conditions were simulated. A passive scalar source was introduced to the forest floor for both simulations. The simulations reproduced the main characteristics of the turbulent flow and of the passive scalar transport between the forest and the atmosphere. Noteworthily, strong and weak wind conditions presented different turbulence structures that drove different patterns of scalar exchange both within and above the forest. These results show how passive scalar concentration is influenced by the wind speed at the canopy top. Additionally, higher wind speeds are related to stronger sweep and ejection regimes, generating more intense plumes that are able to reduce the passive scalar concentration inside the forest canopy. This work was the first that used PALM to investigate scalar transport between the Amazon rainforest and the atmosphere.
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Impacts of Clear-Cutting of a Boreal Forest on Carbon Dioxide, Methane and Nitrous Oxide Fluxes. FORESTS 2020. [DOI: 10.3390/f11090961] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The 2015 Paris Agreement encourages stakeholders to implement sustainable forest management policies to mitigate anthropogenic emissions of greenhouse gases (GHG). The net effects of forest management on the climate and the environment are, however, still not completely understood, partially as a result of a lack of long-term measurements of GHG fluxes in managed forests. During the period 2010–2013, we simultaneously measured carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes using the flux-gradient technique at two clear-cut plots of different degrees of wetness, located in central Sweden. The measurements started approx. one year after clear-cutting, directly following soil scarification and planting. The study focused on robust inter-plot comparisons, spatial and temporal dynamics of GHG fluxes, and the determination of the global warming potential of a clear-cut boreal forest. The clear-cutting resulted in significant emissions of GHGs at both the wet and the dry plot. The degree of wetness determined, directly or indirectly, the relative contribution of each GHG to the total budgets. Faster establishment of vegetation on the wet plot reduced total emissions of CO2 as compared to the dry plot but this was partially offset by higher CH4 emissions. Waterlogging following clear-cutting likely caused both plots to switch from sinks to sources of CH4. In addition, there were periods with N2O uptake at the wet plot, although both plots were net sources of N2O on an annual basis. We observed clear diel patters in CO2, CH4 and N2O fluxes during the growing season at both plots, with the exception of CH4 at the dry plot. The total three-year carbon budgets were 4107 gCO2-equivalent m−2 and 5274 gCO2-equivalent m−2 at the wet and the dry plots, respectively. CO2 contributed 91.8% to the total carbon budget at the wet plot and 98.2% at the dry plot. For the only full year with N2O measurements, the total GHG budgets were 1069.9 gCO2-eqvivalents m−2 and 1695.7 gCO2-eqvivalents m−2 at the wet and dry plot, respectively. At the wet plot, CH4 contributed 3.7%, while N2O contributed 7.3%. At the dry plot, CH4 and N2O contributed 1.5% and 7.6%, respectively. Our results emphasize the importance of considering the effects of the three GHGs on the climate for any forest management policy aiming at enhancing the mitigation potential of forests.
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Machacova K, Vainio E, Urban O, Pihlatie M. Seasonal dynamics of stem N 2O exchange follow the physiological activity of boreal trees. Nat Commun 2019; 10:4989. [PMID: 31676776 PMCID: PMC6825224 DOI: 10.1038/s41467-019-12976-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 10/03/2019] [Indexed: 11/28/2022] Open
Abstract
The role of trees in the nitrous oxide (N2O) balance of boreal forests has been neglected despite evidence suggesting their substantial contribution. We measured seasonal changes in N2O fluxes from soil and stems of boreal trees in Finland, showing clear seasonality in stem N2O flux following tree physiological activity, particularly processes of CO2 uptake and release. Stem N2O emissions peak during the vegetation season, decrease rapidly in October, and remain low but significant to the annual totals during winter dormancy. Trees growing on dry soils even turn to consumption of N2O from the atmosphere during dormancy, thereby reducing their overall N2O emissions. At an annual scale, pine, spruce and birch are net N2O sources, with spruce being the strongest emitter. Boreal trees thus markedly contribute to the seasonal dynamics of ecosystem N2O exchange, and their species-specific contribution should be included into forest emission inventories. Forest soil is known to be a source of the greenhouse gas N2O, but the impact of what is planted in that soil has long been overlooked. Here Machacova and colleagues quantify seasonal N2O fluxes from common boreal tree species in Finland, finding that all trees are net sources of this gas.
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Affiliation(s)
- Katerina Machacova
- Global Change Research Institute of the Czech Academy of Sciences, Belidla 4a, CZ-60300, Brno, Czech Republic.
| | - Elisa Vainio
- Environmental Soil Science, Department of Agricultural Sciences, University of Helsinki, P.O.Box 56, FI-00014, Helsinki, Finland.,Institute for Atmospheric and Earth System Research/Forest Sciences, University of Helsinki, P.O.Box 27, FI-00014, Helsinki, Finland
| | - Otmar Urban
- Global Change Research Institute of the Czech Academy of Sciences, Belidla 4a, CZ-60300, Brno, Czech Republic
| | - Mari Pihlatie
- Environmental Soil Science, Department of Agricultural Sciences, University of Helsinki, P.O.Box 56, FI-00014, Helsinki, Finland.,Institute for Atmospheric and Earth System Research/Forest Sciences, University of Helsinki, P.O.Box 27, FI-00014, Helsinki, Finland.,Viikki Plant Science Centre (ViPS), University of Helsinki, P.O.Box 56, FI-00014, Helsinki, Finland
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Tenuta M, Gao X, Flaten DN, Amiro BD. Lower Nitrous Oxide Emissions from Anhydrous Ammonia Application Prior to Soil Freezing in Late Fall Than Spring Pre-Plant Application. JOURNAL OF ENVIRONMENTAL QUALITY 2016; 45:1133-1143. [PMID: 27380060 DOI: 10.2134/jeq2015.03.0159] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Fall application of anhydrous ammonia in Manitoba is common but its impact on nitrous oxide (NO) emissions is not well known. A 2-yr study compared application before freeze-up in late fall to spring pre-plant application of anhydrous ammonia on nitrous oxide (NO) emissions from a clay soil in the Red River Valley, Manitoba. Spring wheat ( L.) and corn ( L.) were grown on two 4-ha fields in 2011 and 2012, respectively. Field-scale flux of NO was measured using a flux-gradient micrometeorological approach. Late fall treatment did not induce NO emissions soon after application or in winter likely because soil was frozen. Application time did alter the temporal pattern of emissions with late fall and spring pre-plant applications significantly increasing median daily NO flux at spring thaw and early crop growing season, respectively. The majority of emissions occurred in early growing season resulting in cumulative emissions for the crop year being numerically 33% less for late fall than spring pre-plant application. Poor yield in the first year with late fall treatment occurred because of weed and volunteer growth with delayed planting. Results show late fall application of anhydrous ammonia before freeze-up increased NO emissions at thaw and decreased emissions for the early growing season compared to spring pre-plant application. However, improved nitrogen availability of late fall application to crops the following year is required when planting is delayed because of excessive moisture in spring.
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Jeong S, Zhao C, Andrews AE, Bianco L, Wilczak JM, Fischer ML. Seasonal variation of CH4emissions from central California. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd016896] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Vesala T, Huotari J, Rannik Ü, Suni T, Smolander S, Sogachev A, Launiainen S, Ojala A. Eddy covariance measurements of carbon exchange and latent and sensible heat fluxes over a boreal lake for a full open-water period. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jd006365] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Huttunen JT. Nitrous oxide flux to the atmosphere from the littoral zone of a boreal lake. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jd002989] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Ausma S, Edwards GC, Wong EK, Gillespie TJ, Fitzgerald-Hubble CR, Halfpenny-Mitchell L, Mortimer WP. A micrometeorological technique to monitor total hydrocarbon emissions from landfarms to the atmosphere. JOURNAL OF ENVIRONMENTAL QUALITY 2001; 30:776-785. [PMID: 11401267 DOI: 10.2134/jeq2001.303776x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Landfarming is used to treat petroleum hydrocarbon-contaminated soils and a variety of waste streams from industrial operations. Wastes are applied to a soil surface and indigenous soil microorganisms utilize the hydrocarbons in the applied waste as a carbon source for metabolism, thereby biodegrading the applied material. Concerns have been expressed that abiotic losses, such as volatilization, play a significant role in hydrocarbon reduction within the soil. To assist in better defining atmospheric releases of total hydrocarbons from landfarms treating petroleum hydrocarbons, a flux gradient micrometeorological approach was developed and integrated with a custom-built total hydrocarbon detector, and a novel air sampling system and averaging algorithm. The micrometeorological technique offers unobtrusive spatially averaged real-time continuous measurements, thereby providing a time history of emissions. This provides opportunities to investigate mechanisms controlling emissions and to evaluate landfarm management strategies. The versatility of the technique is illustrated through measurements performed at a remote landfarm used to treat diesel fuel-contaminated soil in northern Ontario and during routine operations at two active refinery landfarms in southwestern Ontario.
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Affiliation(s)
- S Ausma
- Dep of Land Resource Science, Univ of Guleph, ON, Canada.
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Edwards GC, Rasmussen PE, Schroeder WH, Kemp RJ, Dias GM, Fitzgerald-Hubble CR, Wong EK, Halfpenny-Mitchell L, Gustin MS. Sources of variability in mercury flux measurements. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000jd900496] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Esler M, Griffith D, Turatti F, Wilson S, Rahn T, Zhang H. N2O concentration and flux measurements and complete isotopic analysis by FTIR spectroscopy. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1465-9972(00)00033-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Gu L, Fuentes JD, Shugart HH, Staebler RM, Black TA. Responses of net ecosystem exchanges of carbon dioxide to changes in cloudiness: Results from two North American deciduous forests. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999jd901068] [Citation(s) in RCA: 184] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Sellers PJ, Hall FG, Kelly RD, Black A, Baldocchi D, Berry J, Ryan M, Ranson KJ, Crill PM, Lettenmaier DP, Margolis H, Cihlar J, Newcomer J, Fitzjarrald D, Jarvis PG, Gower ST, Halliwell D, Williams D, Goodison B, Wickland DE, Guertin FE. BOREAS in 1997: Experiment overview, scientific results, and future directions. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/97jd03300] [Citation(s) in RCA: 376] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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