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| Titel |
Intercomparison of atmospheric water vapor soundings from the differential absorption lidar (DIAL) and the solar FTIR system on Mt. Zugspitze |
| VerfasserIn |
H. Vogelmann, R. Sussmann, T. Trickl, T. Borsdorff |
| 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 ; 4, no. 5 ; Nr. 4, no. 5 (2011-05-09), S.835-841 |
| Datensatznummer |
250001977
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| Publikation (Nr.) |
 copernicus.org/amt-4-835-2011.pdf |
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| Zusammenfassung |
| We present an intercomparison of three years of measurements of integrated water
vapor (IWV) performed by the mid-infrared solar FTIR (Fourier Transform
Infra-Red) instrument on the summit of
Mt. Zugspitze (2964 m a.s.l.) and by the nearby near-infrared differential absorption
lidar (DIAL) at the Schneefernerhaus research station (2675 m a.s.l.). The
solar FTIR was shown to be one of the most accurate and precise IWV
sounders in recent work (Sussmann et al., 2009) and is taken as the reference
here. By calculating the FTIR-DIAL correlation (22 min coincidence interval,
15 min integration time) we derive an almost ideal slope of 0.996 (10), a
correlation coefficient of R = 0.99, an IWV intercept of −0.039 (42) mm (−1.2 % of
the mean), and a bias of −0.052 (26) mm (−1.6 % of the mean) from the scatter plot.
By selecting a subset of coincidences with an optimum temporal and spatial matching
between DIAL and FTIR, we obtain a conservative estimate of the precision of the
DIAL in measuring IWV which is better than 0.1 mm (3.2 % of the mean). We found
that for a temporal coincidence interval of 22 min the difference in IWV
measured by these two systems is dominated by the volume mismatch (horizontal
distance: 680 m). The outcome from this paper is twofold: (1) the IWV soundings
by FTIR and DIAL agree very well in spite of the differing wavelength regions
with different spectroscopic line parameters and retrieval algorithms used. (2) In order to derive an estimate of the precision of state-of-the-art IWV sounders
from intercomparison experiments, it is necessary to use a temporal matching on
time scales shorter than 10 min and a spatial matching on the 100-m scale. |
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