 |
| Titel |
Aerodynamic gradient measurements of the NH3-HNO3-NH4NO3 triad using a wet chemical instrument: an analysis of precision requirements and flux errors |
| VerfasserIn |
V. Wolff, I. Trebs, C. Ammann, F. X. Meixner |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1867-1381
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 3, no. 1 ; Nr. 3, no. 1 (2010-02-10), S.187-208 |
| Datensatznummer |
250000823
|
| Publikation (Nr.) |
 copernicus.org/amt-3-187-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
The aerodynamic gradient method is widely used for flux measurements of
ammonia, nitric acid, particulate ammonium nitrate (the
NH3-HNO3-NH4NO3 triad) and other water-soluble reactive
trace compounds. The surface exchange flux is derived from a measured
concentration difference and micrometeorological quantities (turbulent
exchange coefficient). The significance of the measured concentration
difference is crucial for the significant determination of surface exchange
fluxes. Additionally, measurements of surface exchange fluxes of ammonia,
nitric acid and ammonium nitrate are often strongly affected by phase
changes between gaseous and particulate compounds of the triad, which make
measurements of the four individual species (NH3, HNO3,
NH4+, NO3− necessary for a correct interpretation of
the measured concentration differences.
We present here a rigorous analysis of results obtained with a
multi-component, wet-chemical instrument, able to simultaneously measure
gradients of both gaseous and particulate trace substances. Basis for our
analysis are two field experiments, conducted above contrasting ecosystems
(grassland, forest). Precision requirements of the instrument as well as
errors of concentration differences and micrometeorological exchange
parameters have been estimated, which, in turn, allows the establishment of
thorough error estimates of the derived fluxes of NH3, HNO3,
NH4+, and NO3−. Derived median flux errors for the
grassland and forest field experiments were: 39% and 50% (NH3),
31% and 38% (HNO3), 62% and 57% (NH4+), and
47% and 68% (NO3−), respectively. Additionally, we provide
the basis for using field data to characterize the instrument performance,
as well as subsequent quantification of surface exchange fluxes and
underlying mechanistic processes under realistic ambient measurement
conditions. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|