Atmosphere-Surface Exchange Measurements

Dabberdt, Walter F.; Lenschow, Donald H.; Horst, Thomas; Zimmerman, P. R.; Oncley, Steven; Delany, A. C.

doi:10.1126/science.260.5113.1472

Cited by 136 publications

(88 citation statements)

References 53 publications

(14 reference statements)

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“…They captured NH 3 concentrations integrated over one to several hours (Table 1). The procedure to calculate the EC fluxes (Dabberdt et al, 1993) of NH 3 measured by HT-CIMS is described by Sintermann et al (2011). The EC fluxes were corrected for the amount of high-frequency attenuation in the used closed path system by an empirical ogive approach (Ammann et al, 2006).…”

Section: Field Experimentsmentioning

confidence: 99%

Determination of field scale ammonia emissions for common slurry spreading practice with two independent methods

et al. 2011

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Abstract.At a cropland and a grassland site field scale ammonia (NH 3 ) emissions from slurry application were determined simultaneously by two approaches based on (i) eddy covariance (EC) flux measurements using high temperature Chemical Ionisation Mass Spectrometry (HT-CIMS) and on (ii) backward Lagrangian Stochastic (bLS) dispersion modelling using concentration measurements by three optical open path Fourier Transform Infrared (FTIR) systems. Slurry was spread on the fields in sequential tracks over a period of one to two hours. In order to calculate field emissions, measured EC/HT-CIMS fluxes were combined with flux footprint analysis of individual slurry spreading tracks to parameterise the NH 3 volatilisation with a bi-exponential time dependence. Accordingly, track-resolved concentration footprints for the FTIR measurements were calculated using bLS. A consistency test with concentrations measured by impingers showed very low systematic deviations for the EC/HT-CIMS results (<8 %) but larger deviations for the bLS/FTIR results. For both slurry application events, the period during fertilisation and the subsequent two hours contributed by more than 80 % to the total field emissions. Averaged over the two measurement methods, the cumulated emissions of the first day amounted to 17 ± 3 % loss of applied total ammoniacal nitrogen over the cropland and 16 ± 3 % over the grassland field.

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Section: Field Experimentsmentioning

confidence: 99%

Determination of field scale ammonia emissions for common slurry spreading practice with two independent methods

et al. 2011

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“…The eddy-covariance method is widely considered the most reliable and direct method to determine ecosystem scale fluxes for trace gases and is being widely applied to determine CO 2 and H 2 O exchange between the atmosphere and biosphere (Baldocchi et al, 1988;Dabberdt et al, 1993;Baldocchi, 2003). The method requires a sensor which has very fast response (e.g., 5-20 Hz) and high sensitivity (Businger and Delany, 1990).…”

Section: Introductionmentioning

confidence: 99%

Eddy covariance emission and deposition flux measurements using proton transfer reaction – time of flight – mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes

et al. 2013

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Abstract. During summer 2010, a proton transfer reaction – time of flight – mass spectrometer (PTR-TOF-MS) and a quadrupole proton transfer reaction mass spectrometer (PTR-MS) were deployed simultaneously for one month in an orange orchard in the Central Valley of California to collect continuous data suitable for eddy covariance (EC) flux calculations. The high time resolution (5 Hz) and high mass resolution (up to 5000 m/Δm) data from the PTR-TOF-MS provided the basis for calculating the concentration and flux for a wide range of volatile organic compounds (VOC). Throughout the campaign, 664 mass peaks were detected in mass-to-charge ratios between 10 and 1278. Here we present PTR-TOF-MS EC fluxes of the 27 ion species for which the vertical gradient was simultaneously measured by PTR-MS. These EC flux data were validated through spectral analysis (i.e., co-spectrum, normalized co-spectrum, and ogive). Based on inter-comparison of the two PTR instruments, no significant instrumental biases were found in either mixing ratios or fluxes, and the data showed agreement within 5% on average for methanol and acetone. For the measured biogenic volatile organic compounds (BVOC), the EC fluxes from PTR-TOF-MS were in agreement with the qualitatively inferred flux directions from vertical gradient measurements by PTR-MS. For the 27 selected ion species reported here, the PTR-TOF-MS measured total (24 h) mean net flux of 299 μg C m−2 h−1. The dominant BVOC emissions from this site were monoterpenes (m/z 81.070 + m/z 137.131 + m/z 95.086, 34%, 102 μg C m−2 h−1) and methanol (m/z 33.032, 18%, 72 μg C m−2 h−1). The next largest fluxes were detected at the following masses (attribution in parenthesis): m/z 59.048 (mostly acetone, 12.2%, 36.5 μg C m−2 h−1), m/z 61.027 (mostly acetic acid, 11.9%, 35.7 μg C m−2 h−1), m/z 93.069 (para-cymene + toluene, 4.1%, 12.2 μg C m−2 h−1), m/z 45.033 (acetaldehyde, 3.8%, 11.5 μg C m−2 h−1), m/z 71.048 (methylvinylketone + methacrolein, 2.4%, 7.1 μg C m−2 h−1), and m/z 69.071 (isoprene + 2-methyl-3-butene-2-ol, 1.8%, 5.3 μg C m−2 h−1). Low levels of emission and/or deposition (<1.6% for each, 5.8% in total flux) were observed for the additional reported masses. Overall, our results show that EC flux measurements using PTR-TOF-MS is a powerful new tool for characterizing the biosphere-atmosphere exchange including both emission and deposition for a large range of BVOC and their oxidation products.

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“…Among the micrometeorological methods, the eddy covariance (EC) approach is considered as the most direct for measuring the trace gas exchange of ecosystems (Dabberdt et al, 1993), and it is used as standard method for CO 2 flux monitoring in regional and global networks (e.g., Aubinet et al, 2000;Baldocchi, 2003). Advances in the commercial availability of tunable diode laser spectrometers (Peltola et al, 2013) that measure CH 4 (and N 2 O) concentrations at sampling rates of 10 to 20 Hz have steadily increased the number of ecosystem monitoring sites measuring also the exchange of these GHG.…”

Section: Introductionmentioning

confidence: 99%

Eddy covariance methane flux measurements over a grazed pasture: effect of cows as moving point sources

Felber

Münger²,

Neftel

et al. 2015

Biogeosciences

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Abstract. Methane (CH 4 ) from ruminants contributes onethird of global agricultural greenhouse gas emissions. Eddy covariance (EC) technique has been extensively used at various flux sites to investigate carbon dioxide exchange of ecosystems. Since the development of fast CH 4 analyzers, the instrumentation at many flux sites has been amended for these gases. However, the application of EC over pastures is challenging due to the spatially and temporally uneven distribution of CH 4 point sources induced by the grazing animals. We applied EC measurements during one grazing season over a pasture with 20 dairy cows (mean milk yield: 22.7 kg d −1 ) managed in a rotational grazing system. Individual cow positions were recorded by GPS trackers to attribute fluxes to animal emissions using a footprint model. Methane fluxes with cows in the footprint were up to 2 orders of magnitude higher than ecosystem fluxes without cows. Mean cow emissions of 423 ± 24 g CH 4 head −1 d −1 (best estimate from this study) correspond well to animal respiration chamber measurements reported in the literature. However, a systematic effect of the distance between source and EC tower on cow emissions was found, which is attributed to the analytical footprint model used. We show that the EC method allows one to determine CH 4 emissions of cows on a pasture if the data evaluation is adjusted for this purpose and if some cow distribution information is available.

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Atmosphere-Surface Exchange Measurements

Cited by 136 publications

References 53 publications

Determination of field scale ammonia emissions for common slurry spreading practice with two independent methods

Determination of field scale ammonia emissions for common slurry spreading practice with two independent methods

Eddy covariance emission and deposition flux measurements using proton transfer reaction – time of flight – mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes

Eddy covariance methane flux measurements over a grazed pasture: effect of cows as moving point sources

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