Intercalibration of a passive wind-vane flux sampler against a continuous-flow denuder for the measurements of atmospheric ammonia concentrations and surface exchange fluxes |
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| Institution: | 1. Department of Earth Sciences, University of Aarhus, Ny Munkegade, Building 520, DK-8000 Aarhus C, Denmark;2. Netherlands Energy Research Foundation ECN, P.O. Box. 1 1755 ZG Petten, The Netherlands;3. Institute of Terrestrial Ecology, Edinburgh Research Station, Penicuik, Midlothian EH26 0QB, UK;4. University of Manchester Institute of Science and Technology, P.O. Box. 88, Manchester, M60 1QD, UK;1. Mechanical Power Engineering Department, Higher Technological Institute Tenth of Ramadan City, Egypt, P.O. Box: 228;2. Mechanical Power Engineering Department, Faculty of Engineering EL-Mattaria, Helwan University, P.O Box:11718, Cairo, Egypt;3. Mechanical Engineering Dept., College of Engineering and Islamic Architecture, Umm Al-Qura University, P.O. 5555, Makkah, Saudi Arabia;1. University of Malta, Faculty of Engineering, Department of Mechanical Engineering, Msida, MSD 2080, Malta;2. University of Malta, Faculty of the Built Environment, Department of Environmental Design, MSD 2080, Malta;1. Division of System Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507, Japan;2. Division of Mechanical Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507, Japan;3. National Institute of Advanced Industrial Science and Technology, 1-2-1 Namiki, Tsukuba-shi, Ibaraki 305-8564, Japan;1. Design Engineer Mechanical at Kone Elevators India Pvt Ltd, India;2. SRM Institute of Science and Technlogy, Ramapuram, Chennai, India;3. Department of Mechatronics Engineering, Tishk International University, Erbil, KRG, Iraq |
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| Abstract: | A passive wind-vane flux sampler is a simple low-cost device used to estimate long-term vertical fluxes of ammonia in the atmospheric surface boundary layer. The passive flux sampler measures the horizontal flux of ammonia. A vertical gradient of the horizontal flux, combined with micro-meteorological measurements of wind speed and temperature, is used to estimated the vertical flux of ammonia using a modified aerodynamic gradient technique. The passive wind-vane flux sampler gradient was calibrated against a gradient measured with fast response (6 min) continuous-flow denuders. The measurements were carried out at a heathland located in an intensive farming area in the centre of the Netherlands. A field campaign took place over 70 day period in the summer of 1996, during which the sampling periods of the passive wind-vane flux sampler varied between 3 and 9 days. The comparison clearly showed that the long-term measurements with the passive wind-vane flux samplers gave accurate average ammonia deposition values for the field campaign as a whole which deviated by only 18% from the reference flux. However, there was no significant correlation between the fluxes from the passive samplers and the reference method for the individual 10 periods which were compared. Possible explanations found for the lacking correlation were (I) a high percentage number of half-hour emission events within each period resulted in a significant large relative deviation between the fluxes, and (II) uncertainties in the reference method might also explain the lacking correlation. The passive wind-vane flux samplers proved to be a stable method for long-term measurements (months to years) due to a close to 100% optimal functioning during the field campaign. |
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