Micrometeorological measurement and source region analysis of nitrous oxide fluxes from an agricultural soil

Wienhold, F. G.; Welling, Michael; Harris, G. W.

doi:10.1016/1352-2310(95)00165-u

Cited by 67 publications

(60 citation statements)

References 14 publications

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“…The high-frequency damping mainly depended on the wind speed and ranged between 25% (low wind speed) and 55% (high wind speed). The detection limit of the EC fluxes was determined empirically from the standard deviation of the covariance function at large delay times according to Wienhold et al (1995). It was estimated on average to 0.3 nmol m −2 s −1 and 0.8 nmol m −2 s −1 for the measurements above the intensive and extensive field, respectively.…”

Section: Eddy Covariance Methodsmentioning

confidence: 99%

Methanol exchange between grassland and the atmosphere

et al. 2007

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Abstract. Concentrations and fluxes of methanol were measured above two differently managed grassland fields (intensive and extensive) in central Switzerland during summer 2004. The measurements were performed with a proton-transfer-reaction mass-spectrometer and fluxes were determined by the eddy covariance method. The observed methanol emission showed a distinct diurnal cycle and was strongly correlated with global radiation and water vapour flux. Mean and maximum daily emissions were found to depend on grassland species composition and, for the intensive field, also on the growing state. The extensive field with a more complex species composition had higher emissions than the graminoid-dominated intensive field, both on an area and on a biomass basis. A simple parameterisation depending on the water vapour flux and the leaf area index allowed a satisfying simulation of the temporal variation of methanol emissions over the growing phase. Accumulated carbon losses due to methanol emissions accounted for 0.024 and 0.048% of net primary productivity for the intensive and extensive field, respectively. The integral methanol emissions over the growing periods were more than one order of magnitude higher than the emissions related to cut and drying events.

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Section: Eddy Covariance Methodsmentioning

confidence: 99%

Methanol exchange between grassland and the atmosphere

et al. 2007

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“…Eddy covariance fluxes are usually estimated by maximising the cross-covariance between time series w and χ c . Wienhold et al (1995) developed a method to assess how well this maximum can be detected from the cross-covariance. In their method the detection limit of a flux is estimated as the standard deviation of the cross-covariance function values far from the maximum value, i.e.…”

Section: Random Errors In the Fluxmentioning

confidence: 99%

Evaluating the performance of commonly used gas analysers for methane eddy covariance flux measurements: the InGOS inter-comparison field experiment

et al. 2014

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Abstract. The performance of eight fast-response methane (CH 4 ) gas analysers suitable for eddy covariance flux measurements were tested at a grassland site near the Cabauw tall tower (Netherlands) during June 2012. The instruments were positioned close to each other in order to minimise the effect of varying turbulent conditions. The moderate CH 4 fluxes observed at the location, of the order of 25 nmol m −2 s −1 , provided a suitable signal for testing the instruments' performance.Generally, all analysers tested were able to quantify the concentration fluctuations at the frequency range relevant for turbulent exchange and were able to deliver high-quality data. The tested cavity ringdown spectrometer (CRDS) instruments from Picarro, models G2311-f and G1301-f, were superior to other CH 4 analysers with respect to instrumental noise. As an open-path instrument susceptible to the effects of rain, the LI-COR LI-7700 achieved lower data coverage and also required larger density corrections; however, the system is especially useful for remote sites that are restricted in power availability. In this study the open-path LI-7700 results were compromised due to a data acquisition problem in our data-logging setup. Some of the older closed-path analysers tested do not measure H 2 O concentrations alongside CH 4 (i.e. FMA1 and DLT-100 by Los Gatos Research) and this complicates data processing since the required corrections for dilution and spectroscopic interactions have to be based on external information. To overcome this issue, we used H 2 O mole fractions measured by other gas analysers, adjusted them with different methods and then applied them to correct the CH 4 fluxes. Following this procedure we estimated a bias of the order of 0.1 g (CH 4 ) m −2 (8 % of the measured mean flux) in the processed and corrected CH 4 fluxes on a monthly scale due to missing H 2 O concentration measurements. Finally, cumulative CH 4 fluxes over 14 days from three closed-path gas analysers, G2311-f (Picarro Inc.), FGGA (Los Gatos Research) and FMA2 (Los Gatos Research), which were measuring H 2 O concentrations in addition to CH 4 , agreed within 3 % (355-367 mg (CH 4 ) m −2 ) and were not clearly different from each other, whereas the other instruments derived total fluxes which showed small but distinct differences (±10 %, 330-399 mg (CH 4 ) m −2 ).Published by Copernicus Publications on behalf of the European Geosciences Union. 3164O. Peltola et al.: Evaluating the performance of gas analysers for CH 4 EC flux measurements

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“…To estimate the error of the flux determination, the standard deviation of the covariance of w and c was calculated using time lags in the region of 1 to 1.5 s and 7.5 to 8 s in 0.05 s intervals, which is far away from the time lag used for flux determination (∼4.5 s) and regarded as a background (Wienhold et al, 1995;Spirig et al, 2005;Brunner et al, 2007). As a mean value, the estimated error in the flux determination (2σ ) was found to be 25 µg C m −2 h −1 for isoprene and 19 µg C m −2 h −1 for methanol.…”

Section: Disjunct Eddy Covariance Technique (Dec)mentioning

confidence: 99%

BVOC ecosystem flux measurements at a high latitude wetland site

et al. 2010

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Abstract. In this study, we present summertime concentrations and fluxes of biogenic volatile organic compounds (BVOCs) measured at a sub-arctic wetland in northern Sweden using a disjunct eddy-covariance (DEC) technique based on a proton transfer reaction mass spectrometer (PTR-MS). The vegetation at the site was dominated by Sphagnum, Carex and Eriophorum spp. The measurements reported here cover a period of 50 days (1 August to 19 September 2006), approximately one half of the growing season at the site, and allowed to investigate the effect of day-to-day variation in weather as well as of vegetation senescence on daily BVOC fluxes, and on their temperature and light responses. The sensitivity drift of the DEC system was assessed by comparing H 3 O + -ion cluster formed with water molecules (H 3 O + (H 2 O) at m37) with water vapour concentration measurements made using an adjacent humidity sensor, and the applicability of the DEC method was analysed by a comparison of sensible heat fluxes for high frequency and DEC data obtained from the sonic anemometer. These analyses showed no significant PTR-MS sensor drift over a period of several weeks and only a small flux-loss due to high-frequency spectrum omissions. This loss was within the range expected from other studies and the theoretical considerations.Standardised (20 • C and 1000 µmol m −2 s −1 PAR) summer isoprene emission rates found in this study of 329 µg C m −2 (ground area) h −1 were comparable with findings from more southern boreal forests, and fen-like ecosystems. On a diel scale, measured fluxes indicated a stronger temperature dependence than emissions from temperate or (sub)tropical ecosystems. For the first time, to our knowledge, we report ecosystem methanol fluxes from a sub-arctic Correspondence to: T. Holst (thomas.holst@nateko.lu.se) ecosystem. Maximum daytime emission fluxes were around 270 µg m −2 h −1 (ca. 100 µg C m −2 h −1 ), and during most nights small negative fluxes directed from the atmosphere to the surface were observed.

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Micrometeorological measurement and source region analysis of nitrous oxide fluxes from an agricultural soil

Cited by 67 publications

References 14 publications

Methanol exchange between grassland and the atmosphere

Methanol exchange between grassland and the atmosphere

Evaluating the performance of commonly used gas analysers for methane eddy covariance flux measurements: the InGOS inter-comparison field experiment

BVOC ecosystem flux measurements at a high latitude wetland site

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