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| Titel |
Two decades of water vapor measurements with the FISH fluorescence hygrometer: A review |
| VerfasserIn |
Christian Rolf, Jessica Meyer, Cornelius Schiller, Susanne Rohs, Nicole Spelten, Armin Afchine, Martin Zöger, Nikolay Sitnikov, Troy D. Thornberry, Andrew W. Rollins, Zoltan Bozoki, Dávid Tátrai, Volker Ebert, Benjamin Kühnreich, Peter Mackrodt, Ottmar Möhler, Harald Saathoff, Karen H. Rosenlof, Martina Krämer |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250107321
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| Publikation (Nr.) |
 EGU/EGU2015-7018.pdf |
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| Zusammenfassung |
| The Fast In-situ Stratospheric Hygrometer (FISH) is an airborne Lyman-α photofragment
fluorescence hygrometer for accurate and precise measurement of total water mixing
ratios (WMR) (gas phase + evaporated ice) in the upper troposphere and lower
stratosphere (UT/LS) since almost two decades. Here, we present a comprehensive review
of the measurement technique, calibration procedure, accuracy and reliability of
FISH.
A crucial part for the FISH measurement quality is the regular calibration to a water vapor
reference, namely the commercial frostpoint hygrometer DP30. In the frame of this work this
frostpoint 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 4-1000 ppmv, the
total accuracy of FISH was found to be 6-8 % as stated also 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 ppmv 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.
Further, 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%Â@10ppmv.
We will show here that the robust and continuous calibration and operation
procedures of the FISH instrument over the last two decades establish FISH as
one of the core instruments for in-situ observations of water vapor in the UT/LS. |
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