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| Titel |
A high-resolution oxygen A-band spectrometer (HABS) and its radiation closure |
| VerfasserIn |
Q. Min, B. Yin, S. Li, J. Berndt, L. Harrison, E. Joseph, M. Duan, P. Kiedron |
| 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 ; 7, no. 6 ; Nr. 7, no. 6 (2014-06-17), S.1711-1722 |
| Datensatznummer |
250115819
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| Publikation (Nr.) |
 copernicus.org/amt-7-1711-2014.pdf |
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| Zusammenfassung |
| Various studies indicate that high-resolution oxygen A-band spectrum has the
capability to retrieve the vertical profiles of aerosol and cloud properties.
To improve the understanding of oxygen A-band inversions and utility, we
developed a high-resolution oxygen A-band spectrometer (HABS), and deployed
it at Howard University Beltsville site during the NASA Discover Air-Quality
Field Campaign in July, 2011. By using a single telescope, the HABS
instrument measures the direct solar and the zenith diffuse radiation
subsequently. HABS exhibits excellent performance: stable spectral response
ratio, high signal-to-noise ratio (SNR), high-spectrum resolution
(0.016 nm), and high out-of-band rejection (10−5). For the spectral
retrievals of HABS measurements, a simulator is developed by combining a
discrete ordinates radiative transfer code (DISORT) with the High Resolution
Transmission (HITRAN) database HITRAN2008. The simulator uses a double-k
approach to reduce the computational cost. The HABS-measured spectra are
consistent with the related simulated spectra. For direct-beam spectra, the
discrepancies between measurements and simulations, indicated by confidence
intervals (95%) of relative difference, are (−0.06, 0.05) and
(−0.08, 0.09) for solar zenith angles of 27 and 72°, respectively.
For zenith diffuse spectra, the related discrepancies between measurements
and simulations are (−0.06, 0.05) and (−0.08, 0.07) for solar zenith
angles of 27 and 72°, respectively. The main discrepancies between
measurements and simulations occur at or near the strong oxygen absorption
line centers. They are mainly due to two kinds of causes: (1) measurement
errors associated with the noise/spikes of HABS-measured spectra, as a result
of combined effects of weak signal, low SNR, and errors in wavelength
registration; (2) modeling errors in the simulation, including the error of
model parameters setting (e.g., oxygen absorption line parameters, vertical
profiles of temperature and pressure) and the lack of treatment of the
rotational Raman scattering. The high-resolution oxygen A-band measurements
from HABS can constrain the active radar retrievals for more accurate cloud
optical properties (e.g., cloud optical depth, effective radius),
particularly for multi-layer clouds and for mixed-phase clouds. |
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