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| Titel |
A fiber-coupled laser hygrometer for airborne total water measurement |
| VerfasserIn |
S. W. Dorsi, L. E. Kalnajs, D. W. Toohey, L. M. Avallone |
| 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. 1 ; Nr. 7, no. 1 (2014-01-27), S.215-223 |
| Datensatznummer |
250115568
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| Publikation (Nr.) |
 copernicus.org/amt-7-215-2014.pdf |
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| Zusammenfassung |
| The second-generation University of Colorado closed-path tunable-diode laser
hygrometer (CLH-2) is an instrument for the airborne in situ measurement of
total water content – the sum of vapor-, liquid- and ice-phase water – in
clouds. This compact instrument has been flown on the NSF/NCAR Gulfstream-V
aircraft in an underwing canister. It operates autonomously and uses
fiber-coupled optics to eliminate the need for a supply of dry compressed
gas. In operation, sample air is ingested into a forward-facing
sub-isokinetic inlet; this sampling configuration results in particle
concentrations that are enhanced relative to ambient and causes greater
instrument sensitivity to condensed water particles. Heaters within the inlet
vaporize the ingested water particles, and the resulting augmented water
vapor mixing ratio is measured by absorption of near-infrared light in a
single-pass optical cell. The condensed water content is then determined by
subtracting the ambient water vapor content from the total and by accounting
for the inertial enhancement of particles into the sampling inlet. The CLH-2
is calibrated in the laboratory over a range of pressures and water vapor
mixing ratios; the uncertainty in CLH-2 condensed water retrievals is
estimated to be 14.3% to 16.1% (1-σ). A vapor-only laboratory
intercomparison with the first-generation University of Colorado closed-path
tunable-diode laser hygrometer (CLH) shows agreement within the 2-σ
uncertainty bounds of both instruments. |
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