 |
| Titel |
Tropospheric vertical column densities of NO2 over managed dryland ecosystems (Xinjiang, China): MAX-DOAS measurements vs. 3-D dispersion model simulations based on laboratory-derived NO emission from soil samples |
| VerfasserIn |
B. Mamtimin, T. Behrendt, M. M. Badawy, T. Wagner, Y. Qi, Z. Wu, F. X. Meixner |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 2 ; Nr. 15, no. 2 (2015-01-23), S.867-882 |
| Datensatznummer |
250119344
|
| Publikation (Nr.) |
 copernicus.org/acp-15-867-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| We report on MAX-DOAS observations of NO2 over an oasis–ecotone–desert
ecosystem in NW China. There, local ambient NO2 concentrations
originate from enhanced biogenic NO emission of intensively managed soils.
Our target oasis "Milan" is located at the southern edge of the Taklimakan
desert, very remote and well isolated from other potential anthropogenic and
biogenic NOx sources. Four observation sites for MAX-DOAS measurements
were selected, at the oasis centre, downwind and upwind of the oasis, and in
the desert. Biogenic NO emissions in terms of (i) soil moisture and (ii)
soil temperature of Milan oasis (iii) different land-cover type sub-units
(cotton, Jujube trees, cotton/Jujube mixture, desert) were quantified by
laboratory incubation of corresponding soil samples. Net potential NO fluxes
were up-scaled to oasis scale by areal distribution and classification of
land-cover types derived from satellite images using GIS techniques. A
Lagrangian dispersion model (LASAT, Lagrangian Simulation of
Aerosol Transport) was used to calculate the dispersion of soil emitted NO
into the atmospheric boundary layer over Milan oasis. Three-dimensional (3-D) NO
concentrations (30 m horizontal resolution) have been converted to 3-D NO2 concentrations, assuming photostationary state
conditions. NO2 column densities were simulated by suitable vertical
integration of modelled 3-D NO2 concentrations at those downwind and
upwind locations, where the MAX-DOAS measurements were performed.
Downwind–upwind differences (a direct measure of Milan oasis' contribution
to the areal increase of ambient NO2 concentration) of measured and
simulated slant (as well as vertical) NO2 column densities show
excellent agreement. This agreement is considered as the first successful
attempt to prove the validity of the chosen approach to up-scale laboratory-derived biogenic NO fluxes to ecosystem field conditions, i.e. from the
spatial scale of a soil sample (cm2) to the size of an entire
agricultural ecosystem (km2). |
| |
|
| Teil von |
|
|
|
|
|
|
|
|