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| Titel |
Two decades of water vapor measurements with the FISH fluorescence hygrometer: a review |
| VerfasserIn |
J. Meyer, C. Rolf, C. Schiller, S. Rohs, N. Spelten, A. Afchine, M. Zöger, N. Sitnikov, T. D. Thornberry, A. W. Rollins, Z. Bozóki, D. Tátrai, V. Ebert, B. Kühnreich, P. Mackrodt, O. Möhler, H. Saathoff, K. H. Rosenlof, M. Krämer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 14 ; Nr. 15, no. 14 (2015-07-30), S.8521-8538 |
| Datensatznummer |
250119940
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| Publikation (Nr.) |
 copernicus.org/acp-15-8521-2015.pdf |
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| Zusammenfassung |
For almost two decades, the airborne Fast In-situ Stratospheric Hygrometer (FISH)
has stood for accurate and precise measurements of total water mixing ratios
(WMR, gas phase + evaporated ice) in the upper troposphere and lower stratosphere
(UT/LS). Here, we present a comprehensive
review of the measurement technique (Lyman-α photofragment fluorescence),
calibration procedure, accuracy and reliability of FISH. Crucial for FISH measurement
quality is the regular calibration to a water vapor reference, namely
the commercial frost-point hygrometer DP30. In the frame of this work
this frost-point hygrometer is compared to German and British traceable
metrological water standards and its accuracy is found to be
2–4 %. Overall, in the range from 4 to 1000 ppmv, the
total accuracy of FISH was found to be 6–8 %, as stated
in previous publications. For lower mixing ratios down to
1 ppmv, the uncertainty reaches a lower limit of
0.3 ppmv. For specific, non-atmospheric conditions, as set
in experiments at the AIDA chamber – namely mixing ratios below 10 and
above 100 ppmv in combination with high- and low-pressure
conditions – the need to apply a modified FISH calibration evaluation
has been identified. The new evaluation improves the agreement of FISH
with other hygrometers to ± 10 % accuracy in the
respective mixing ratio ranges. Furthermore, a quality check procedure for
high total water measurements in cirrus clouds at high pressures
(400–500 hPa) is introduced. The performance of FISH in the
field is assessed by reviewing intercomparisons of FISH water vapor
data with other in situ and remote sensing hygrometers over the last
two decades. We find that the agreement of FISH with the other
hygrometers has improved over that time span from overall up to
± 30 % or more to about
± 5–20 % @ < 10 ppmv and to
± 0–15 % @ > 10 ppmv.
As presented here, the robust and continuous calibration and operation
procedures of the FISH instrument over the last two decades establish
the position of FISH as one of the core instruments for in situ
observations of water vapor in the UT/LS. |
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