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| Titel |
Evaluation and gap-filling of soil NO flux dataset measured at a Hungarian semi-arid grassland |
| VerfasserIn |
László Horváth, Dóra Hidy, Tamás Weidinger |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250111519
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| Publikation (Nr.) |
 EGU/EGU2015-11650.pdf |
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| Zusammenfassung |
| An Integrated Project ÉCLAIRE (http://www.eclaire-fp7.eu/) started in 2011 among others to
study the effect of climate change on air pollution impacts. One of the main measurement
tasks of this project was the continuous monitoring of soil NO emission at different kinds of
lands (forest, arable, grass). Among the tree grass stations Bugacpuszta (central part of
Hungary between the Danube and the Tisza) was selected to monitor and report soil NO
fluxes continuously for 17 months on hourly basis. The climate is semi-arid temperate
continental, the mean annual temperature is 10.7ÂË C, and the average annual precipitation is
around 550Âmm.
Nitric oxide soil emission flux was measured by 2–2 parallel manual and auto dynamic
chambers on hourly basis above a semi-arid, sandy grassland between August 2012 and
January 2014.
Each chamber was sampled for 10Âminutes at a flow rate of 2ÂLÂmin-1 in sequence
each hour all together for 40Âminutes; in the remaining 20Âminutes concentration
gradients were measured by a mast at two heights. Soil temperature and moisture were
measured a few meters apart from the chambers. A computer controlled valve system
was switched the different channels in turn. The output concentrations of nitric
oxide and ozone were measured by HORIBAÂgas monitors through Teflon tubing.
Micrometeorological measurements (energy budget components, CO2 and O3 fluxes) were
also provided.
The initial NO flux datasets covered 43–85% of time period depending on chambers.
Measured flux data ranges within 0–6ÂnmolÂm-2 s-1. We applied a gap-filling method
based on multivariable analysis (Sigma Plot) combined with maximum likelihood method
using the soil temperature and moisture data. Trend of gap-filled flux dataset shows large
peaks mostly in summer and early fall. When soil parameters are far from the optimum (dry,
warm conditions) the fluxes are negligible. Application of manual chambers closed for longer
period results in substantial positive bias in flux estimation compared to auto chambers a
consequence of measurement setup, different temperature and drier soil conditions below the
chamber. Mean fluxes applying permanently closed dynamic chambers are approximately
three times higher compared with auto chambers, 0.176±0.489ÂnmolÂm-2 s-1 and
0.058±0.130ÂnmolÂm-2 s-1 respectively from the all measured and gap filled data. |
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