Quality Control and Flux Sampling Problems for Tower and Aircraft Data

Vickers, Dean; Mahrt, L.

doi:10.1175/1520-0426(1997)014<0512:qcafsp>2.0.co;2

Cited by 1,419 publications

(960 citation statements)

References 10 publications

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“…These uncertainties and errors have been discussed in detail elsewhere (e.g. Goulden et al, 1996;Moncrieff et al, 1996;Vickers and Mahrt, 1997;Wilson et al, 2002;Su et al, 2004). Here, issues of particular importance in the urban environment are highlighted.…”

Section: Introductionmentioning

confidence: 94%

Heat storage and anthropogenic heat flux in relation to the energy balance of a central European city centre

Offerle

Grimmond

Fortuniak

2005

Intl Journal of Climatology

191

151

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The role of net heat storage Q S and anthropogenic heat Q F are considered in the surface energy balance for a downtown area in Łódź, Poland, for a 2 year period. Eddy covariance measurements provide estimates of the turbulent heat fluxes and radiometric measurements of the net all-wave radiation. A method to determine Q S based on representative surface temperature sampling is employed and compared with results from two other models. Results show that Q S is an important flux on the scale of hours to days and that it can be more than 10 W m −2 , on average, for periods of a week or more. By incorporating Q S estimates over hourly intervals, Q F was then determined as the residual of the energy balance. Using the approach, Q F averaged 32 W m −2 from October to March (60% of available energy), and −3 W m −2 from June to August. The physically unrealistic negative values for the summer period may suggest underestimation of turbulent fluxes, but no causal factor was identified. Although energy balance closure was close to 100% throughout the year, there was weaker agreement in the winter. This is attributed to errors in estimates of Q S and variation in Q F . Results highlight the need for future investigations of the urban surface energy balance to incorporate more complete measurements and estimates of Q S .

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Section: Introductionmentioning

confidence: 94%

Heat storage and anthropogenic heat flux in relation to the energy balance of a central European city centre

Offerle

Grimmond

Fortuniak

2005

Intl Journal of Climatology

191

151

View full text Add to dashboard Cite

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“…The data were post-processed to compute halfhourly fluxes with EddyPro (Version 5.0, www.licor.com/ eddypro). Raw EC data were despiked and quality tested (Vickers and Mahrt, 1997). Instantaneous wind vectors were corrected (Nakai and Shimoyama, 2012), then double-rotated and expressed relative to the mean streamlines.…”

Section: Carbon Dioxide and Water Vapour Flux Measurementsmentioning

confidence: 99%

Carbon budgets for an irrigated intensively grazed dairy pasture and an unirrigated winter-grazed pasture

et al. 2016

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Abstract. Intensification of pastoral agriculture is occurring rapidly across New Zealand, including increasing use of irrigation and fertiliser application in some regions. While this enables greater gross primary production (GPP) and livestock grazing intensity, the consequences for the net ecosystem carbon budget (NECB) of the pastures are poorly known. Here, we determined the NECB over one year for an irrigated, fertilised and rotationally grazed dairy pasture and a neighbouring unirrigated, unfertilised, wintergrazed pasture. Primary terms in the NECB calculation were: net ecosystem production (NEP), biomass carbon removed by grazing cows and carbon (C) input from their excreta. Annual NEP was measured using the eddy-covariance method. Carbon removal was estimated with plate-meter measurements calibrated against biomass collections, preand post-grazing. Excreta deposition was calculated from animal feed intake. The intensively managed pasture gained C (NECB = 103 ± 42 g C m −2 yr −1 ) but would have been subject to a non-significant C loss if cattle excreta had not been returned to the pasture. The unirrigated pasture was C-neutral (NECB = −13 ± 23 g C m −2 yr −1 ). While annual GPP of the former was almost twice that of the latter (2679 vs. 1372 g C m −2 yr −1 ), ecosystem respiration differed by only 68 % between the two pastures (2271 vs. 1352 g C m −2 yr −1 ). The ratio of GPP to the total annual water input of the irrigated pasture was 37 % greater than that of the unirrigated pasture, i.e. the former used the water input more efficiently than the latter to produce biomass. The NECB results agree qualitatively with those from many other eddy-covariance studies of grazed grasslands, but they seem to be at odds with long-term carbon-stock studies of other New Zealand pastures.

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“…The calibration and maintenance procedures of the O 3 analyzer were described in detail by Keronen et al (2003). The data were sampled at 21 Hz and a 2-D rotation of sonic anemometer wind components (McMillen et al, 1998) and filtering to eliminate spikes were performed according to standard methods (Vickers and Mahrt, 1997). The high-frequency flux attenuation was corrected by using empirical transfer functions and co-spectral transfer characteristics (Keronen et al, 2003;Rannik et al, 2004;Mammarella et al, 2009).…”

Section: Measurement Of Turbulent Fluxesmentioning

confidence: 99%

Ozone deposition into a boreal forest over a decade of observations: evaluating deposition partitioning and driving variables

et al. 2012

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Abstract. This study scrutinizes a decade-long series of ozone deposition measurements in a boreal forest in search for the signature and relevance of the different deposition processes. The canopy-level ozone flux measurements were analysed for deposition characteristics and partitioning into stomatal and non-stomatal fractions, with the main focus on growing season day-time data. Ten years of measurements enabled the analysis of ozone deposition variation at different time-scales, including daily to inter-annual variation as well as the dependence on environmental variables and concentration of biogenic volatile organic compounds (BVOCs). Stomatal deposition was estimated by using multi-layer canopy dispersion and optimal stomatal control modelling from simultaneous carbon dioxide and water vapour flux measurements, non-stomatal was inferred as residual. Also, utilising the big-leaf assumption stomatal conductance was inferred from water vapour fluxes for dry canopy conditions. The total ozone deposition was highest during the peak growing season (4 mm s −1 ) and lowest during winter dormancy (1 mm s −1 ). During the course of the growing season the fraction of the non-stomatal deposition of ozone was determined to vary from 26 to 44 % during day time, increasing from the start of the season until the end of the growing season. By using multi-variate analysis it was determined that day-time total ozone deposition was mainly driven by photosynthetic capacity of the canopy, vapour pressure deficit (VPD), photosynthetically active radiation and monoterpene concentration. The multi-variate linear model explained the high portion of ozone deposition variance on daily average level (R 2 = 0.79). The explanatory power of the multivariate model for ozone non-stomatal deposition was much lower (R 2 = 0.38). The set of common environmental variables and terpene concentrations used in multivariate analysis were able to predict the observed average seasonal variation in total and non-stomatal deposition but failed to explain the inter-annual differences, suggesting that some still unknown mechanisms might be involved in determining the inter-annual variability. Model calculation was performed to evaluate the potential sink strength of the chemical reactions of ozone with sesquiterpenes in the canopy air space, which revealed that sesquiterpenes in typical amounts at the site were unlikely to cause significant ozone loss in canopy air space. The results clearly showed the importance of several non-stomatal removal mechanisms. Unknown chemical compounds or processes correlating with monoterpene concentrations, including potentially reactions at the surfaces, contribute to non-stomatal sink term.

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Quality Control and Flux Sampling Problems for Tower and Aircraft Data

Cited by 1,419 publications

References 10 publications

Heat storage and anthropogenic heat flux in relation to the energy balance of a central European city centre

Heat storage and anthropogenic heat flux in relation to the energy balance of a central European city centre

Carbon budgets for an irrigated intensively grazed dairy pasture and an unirrigated winter-grazed pasture

Ozone deposition into a boreal forest over a decade of observations: evaluating deposition partitioning and driving variables

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