%0 Journal Article
%A Filges, Annette
%A Gerbig, Christoph
%A Rella, Chris W.
%A Hoffnagle, John
%A Smit, Herman
%A Krämer, Martina
%A Spelten, Nicole
%A Rolf, Christian
%A Bozóki, Zoltán
%A Buchholz, Bernhard
%A Ebert, Volker
%T Evaluation of the IAGOS-Core GHG package H$_{2}$O measurements during the DENCHAR airborne inter-comparison campaign in 2011
%J Atmospheric measurement techniques
%V 11
%N 9
%@ 1867-8548
%C Katlenburg-Lindau
%I Copernicus
%M FZJ-2018-05408
%P 5279 - 5297
%D 2018
%X As part of the DENCHAR (Development and Evaluation of Novel Compact Hygrometer for Airborne Research) inter-comparison campaign in northern Germany in 2011, a commercial cavity ring-down spectroscopy (CRDS) based gas analyzer (G2401-m, Picarro Inc., US) was installed on a Learjet to measure atmospheric water vapor, CO2, CH4, and CO. The CRDS components were identical to those chosen for integration aboard commercial airliners within the IAGOS (In-service Aircraft for a Global Observing System) project. Since the quantitative capabilities of the CRDS water vapor measurements were never evaluated and reviewed in detail in a publication before, the campaign allowed for an initial assessment of the long-term IAGOS water vapor measurements by CRDS against reference instruments with a long performance record (Fast In-situ Stratospheric Hygrometer (FISH) and CR-2 frost point hygrometer (Buck Research Instruments L.L.C., US), both operated by Research Centre Jülich).For the initial water calibration of the instrument it was compared against a dew point mirror (Dewmet TDH, Michell Instruments Ltd., UK) in the range from 70000 to 25000ppm water vapor mole fraction. During the inter-comparison campaign the analyzer was compared on the ground over the range from 2 to 600ppm against the dew point hygrometer used for calibration of the FISH reference instrument. A new, independent calibration method based on the dilution effect of water vapor on CO2 was evaluated.Comparison of the in-flight data against the reference instruments showed that the analyzer is reliable and has a good long-term stability. The flight data suggest a conservative precision estimate for measurements made at 0.4Hz (2.5s measurement interval) of 4ppm for H2O<10ppm, 20% or 10ppm (whichever is smaller) for 10ppm<H2O<100ppm, and 5% or 30ppm (whichever is smaller) for H2O>100ppm. Accuracy of the CRDS instrument was estimated, based on laboratory calibrations, as 1% for the water vapor range from 25000ppm down to 7000ppm, increasing to 5% at 50ppm water vapor. Accuracy at water vapor mole fractions below 50ppm was difficult to assess, as the reference systems suffered from lack of data availability.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000444987500002
%R 10.5194/amt-11-5279-2018
%U https://juser.fz-juelich.de/record/852462