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  • 1
    Electronic Resource
    Electronic Resource
    A micrometeorological investigation of surface exchange of O3, SO2 and NO2: A case study (1989)
    Springer
    Boundary layer meteorology 47 (1989), S. 321-336 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Data obtained in an intensive field study of the dry deposition of sulfur dioxide, ozone, and nitrogen dioxide, conducted in 1985 in central Pennsylvania, are used to illustrate the factors that must be considered to assure that high quality results are derived. In particular, the quality of the site must be such that flux measurements made above the surface are representative of surface values. For this purpose, tests involving momentum transfer and the surface energy budget are especially useful. In addition, conditions must not be changing rapidly, and the statistical uncertainty associated with flux measurement must be low. For the set of data presented here, conservative quality-assurance guidelines are used to reject potentially erroneous flux data. For ozone, most of the measured fluxes are of use in deriving surface resistances. For SO2, far fewer data points are available. For NO2, fluxes appear to lack the order of the O3 and SO2 fluxes, and do not enable surface resistances to be computed. The highest-quality SO2 and O3 data yield surface resistances in fair average agreement with model predictions for SO2, but substantially higher than predictions for O3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00122337
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Methane emissions from a landfill measured by eddy correlation using a fast response diode laser sensor (1995)
    Springer
    Journal of atmospheric chemistry 20 (1995), S. 141-162 
    Details
    ISSN: 1573-0662
    Keywords: Methane ; carbon dioxide ; flux ; landfill ; diode laser ; eddy correlation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We describe a fast response methane sensor based on the absorption of radiation generated with a near-infrared InGaAsP diode laser. The sensor uses an open path absorption region 0.5 m long; multiple pass optics provide an optical path of 50 m. High frequency wavelength modulation methods give stable signals with detection sensitivity (S/N=1, 1 Hz bandwidth) for methane of 65 ppb at atmospheric pressure and room temperature. Improvements in the optical stability are expected to lower the current detection limit. We used the new sensor to measure, by eddy correlation, the CH4 flux from a clay-capped sanitary landfill. Simultaneously we measured the flux of CO2 and H2O. From seven half-hourly periods of data collected after a rainstorm on November 23, 1991, the average flux of CH4 was 17 mmol m−2 hr−1 (6400 mg CH4 m−2 d−1) with a coefficient of variation of 25%. This measurement may underrepresent the flux by 15% due to roll-off of the sensor response at high frequency. The landfill was also a source of CO2 with an average flux of 8.1 mmol m−2 hr−1 (8550 mg CO2 m−2 d−1) and a coefficient of variation of 26%. A spectral analysis of the data collected from the CH4, CO2, and H2O sensors showed a strong similarity in the turbulent transfer mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696555
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Combining biology, chemistry, and meteorology in modeling and measuring dry deposition (1988)
    Springer
    Journal of atmospheric chemistry 6 (1988), S. 117-131 
    Details
    ISSN: 1573-0662
    Keywords: Air-surface exchange ; gas exchange ; turbulent transfer ; ozone fluxes ; sulfur dioxide fluxes ; NOx fluxes ; surface exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The range of chemical, biological, and meteorological processes contributing to the net exchange of trace chemical species between the atmosphere and the underlying surface is examined, in the context of a multiple-resistance exchange model. For those chemical species known to be always depositing, the resistance model provides a means to formulate appropriate deposition velocities in a convenient manner; however, extension to other situations is not straightforward. Field data indicate that the multiple-resistance approach is appropriate for application to assess the dry deposition of ozone and sulfur dioxide, but is not as appropriate for nitrogen dioxide. Data obtained over agricultural crops suggest that canopy factors frequently dominate the overall exchange process. A trial program of dry deposition measurement based on application of parameterized deposition velocities was initiated late in 1984, and has demonstrated shortcomings in under-standing concerning several factors, most importantly the roles of surface emissions and wetness, and the scaling-up of laboratory results to describe vegetative canopies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048335
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A comparison of estimated and measured SO2 deposition velocities (1987)
    Springer
    Water, air & soil pollution 36 (1987), S. 331-347 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A nested-network program for obtaining data on the dry deposition of SO2 and SO4 − has been initiated at a small array of locations (6 in 1985, presently 13) across North America. The procedures involved rely on the availability of models for deriving dry deposition rates from observations of air concentrations and of meteorological and surface properties known to influence the deposition velocity. At a subset of locations (i.e., 3), the results obtained by this indirect method are tested by comparison against more direct methods. One of the first comparison experiments of this series was conducted at Oak Ridge in July 1985 when the fluxes determined by inferential methods were compared to those measured by eddy correlation. The results obtained suggest that initial computer routines, developed to estimate deposition velocity for SOz on a routine basis, overestimate the deposition velocity by about 20% to a mixed-species deciduous forest. The difference is possibly due to the omission of water stress as a contributing factor in the initial computer routines, but might also be associated with chemical processes at the substomatal level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229676
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    A preliminary multiple resistance routine for deriving dry deposition velocities from measured quantities (1987)
    Springer
    Water, air & soil pollution 36 (1987), S. 311-330 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Because there is no simple device capable of measuring the dry deposition rates of small particles and trace gases directly, much current activity is focused on the use of an inferential technique. In this method, measurements of atmospheric concentration (C) of selected chemical species are coupled with evaluations of appropriate deposition velocity (V d ) to yield estimates of dry deposition rate from their product. Difficulties arise concerning the ability to measure C, and especially regarding the poor knowledge of V d for many species. A multiple resistance routine for deriving deposition velocities is presented here. Current knowledge of biological processes is incorporated into a first-generation lsbig leaf’ model; formulations of resistances appropriate for describing individual leaves are combined to simulate the canopy as a whole. The canopy resistance is combined with estimates of aerodynamic and boundary-layer resistances to approximate the total resistance to transfer, from which deposition velocity is then computed. Special emphasis is given to the influence of the diurnal cycle, to the way in which the various transfer resistances can be inferred from routine data, and to the role of canopy factors (e.g., leaf area index, wetness, temperature response, and sunshade fractions).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229675
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    Paper (German National Licenses)
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