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| Titel |
Cross-track Infrared Sounder (CrIS) satellite observations of tropospheric ammonia |
| VerfasserIn |
M. W. Shephard, K. E. Cady-Pereira |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 3 ; Nr. 8, no. 3 (2015-03-19), S.1323-1336 |
| Datensatznummer |
250116219
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| Publikation (Nr.) |
 copernicus.org/amt-8-1323-2015.pdf |
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| Zusammenfassung |
| Observations of atmospheric ammonia are important in understanding and
modelling the impact of ammonia on both human health and the natural
environment. We present a detailed description of a robust retrieval
algorithm that demonstrates the capabilities of utilizing Cross-track
Infrared Sounder (CrIS) satellite observations to globally retrieval ammonia
concentrations. Initial ammonia retrieval results using both simulated and
real observations show that (i) CrIS is sensitive to ammonia in the
boundary layer with peak vertical sensitivity typically around
~ 850–750 hPa (~ 1.5 to 2.5 km), which can dip
down close to the surface (~ 900 hPa) under ideal conditions,
(ii) it has a minimum detection limit of ~ 1 ppbv (peak profile
value typically at the surface), and (iii) the information content can vary
significantly with maximum values of ~ 1 degree-of-freedom
for signal. Comparisons of the retrieval with simulated "true" profiles
show a small positive retrieval bias of 6% with a standard deviation of
~ ± 20% (ranging from ± 12 to ±
30% over the vertical profile). Note that these uncertainty estimates are
considered as lower bound values as no potential systematic errors are
included in the simulations. The CrIS NH3 retrieval applied over the
Central Valley in CA, USA, demonstrates that CrIS correlates well with the
spatial variability of the boundary layer ammonia concentrations seen by the
nearby Quantum Cascade-Laser (QCL) in situ surface and the Tropospheric
Emission Spectrometer (TES) satellite observations as part of the
DISCOVER-AQ campaign. The CrIS and TES ammonia observations show
quantitatively similar retrieved boundary layer values that are often within
the uncertainty of the two observations. Also demonstrated is CrIS's ability
to capture the expected spatial distribution in the ammonia concentrations,
from elevated values in the Central Valley from anthropogenic agriculture
emissions, to much lower values in the unpolluted or clean surrounding
mountainous regions. These initial results demonstrate the capabilities of
the CrIS satellite to measure ammonia. |
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