TY  - JOUR
AU  - Filges, Annette
AU  - Gerbig, Christoph
AU  - Rella, Chris W.
AU  - Hoffnagle, John
AU  - Smit, Herman
AU  - Krämer, Martina
AU  - Spelten, Nicole
AU  - Rolf, Christian
AU  - Bozóki, Zoltán
AU  - Buchholz, Bernhard
AU  - Ebert, Volker
TI  - Evaluation of the IAGOS-Core GHG package H$_{2}$O measurements during the DENCHAR airborne inter-comparison campaign in 2011
JO  - Atmospheric measurement techniques
VL  - 11
IS  - 9
SN  - 1867-8548
CY  - Katlenburg-Lindau
PB  - Copernicus
M1  - FZJ-2018-05408
SP  - 5279 - 5297
PY  - 2018
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000444987500002
DO  - DOI:10.5194/amt-11-5279-2018
UR  - https://juser.fz-juelich.de/record/852462
ER  -