Absolute validation of a diode laser hygrometer via intercomparison with the German national primary water vapor standard

Buchholz, Bernhard; Böse, N.; Ebert, Volker

doi:10.1007/s00340-014-5775-4

Cited by 74 publications

(82 citation statements)

References 54 publications

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“…Our recent studies show that absolute spectroscopic measurement techniques (tunable diode laser absorption spectroscopy (TDLAS) or cavity ringdown spectroscopy (CRDS)) provide the potential to achieve traceability in spectroscopic amount fraction measurements without the need for calibration using gas standards [37,38]. Based on absolute spectroscopic techniques an optical transfer standard can be developed, which is independent from gas standards.…”

Section: Absolute Extractive Spectroscopic Techniquesmentioning

confidence: 99%

Metrology for ammonia in ambient air – concept and first results of the EMRP project MetNH3

Pogány¹,

Balslev-Harder²,

Braban³

et al. 2015

17th International Congress of Metrology

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Section: Absolute Extractive Spectroscopic Techniquesmentioning

confidence: 99%

Metrology for ammonia in ambient air – concept and first results of the EMRP project MetNH3

Pogány¹,

Balslev-Harder²,

Braban³

et al. 2015

17th International Congress of Metrology

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“…HAI uses a complete physical model in combination with spectral water absorption line parameters mostly measured at the Physikalisch Technische Bundesanstalt Braunschweig (PTB) (Pogány et al, 2015) and monitors pressure, temperature and absorption 5 path length in order to calculate the water vapor concentration for a given absorption spectrum without prior calibration. The accuracy of this approach was verified recently by a side by side comparison (Buchholz et al, 2014) of a previous PTB laser absorption spectrometer with the German national primary humidity standard. HAI has 1.5 m optical path length for the closed cell and 4.2 m for the open path.…”

Section: Haimentioning

confidence: 79%

Intercomparison of mid-latitude tropospheric and lower stratospheric water vapor measurements and comparison to ECMWF humidity data

Kaufmann¹,

Voigt²,

Heller³

et al. 2018

Preprint

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Abstract. Accurate measurement of water vapor in the climate sensitive region near the tropopause turned out to be very challenging. Unexplained systematic discrepancies between measurements at low water vapor mixing ratios made by different instruments on airborne platforms have limited our ability to adequately address a number relevant scientific questions on the humidity distribution, cloud formation and climate impact in that region. Therefore, during the past decade, the scientific community has undertaken substantial efforts to understand these discrepancies and improve the quality of 20 water vapor measurements. This study presents a comprehensive intercomparison of airborne state-of-the-art in situ hygrometers deployed onboard the DLR (German Aerospace Center) research aircraft HALO during the Mid-Latitude CIRRUS (ML-CIRRUS) campaign conducted in 2014 over central Europe. The instrument intercomparison shows that the hygrometer measurements agree within their combined accuracy (±10 to 15%, depending on the humidity regime), total mean values even agree within 2.5%. However, systematic differences on the order of 10% and up to a maximum of 15% are 25 found for mixing ratios below 10 parts per million (ppm) H 2 O. A comparison of relative humidity within cirrus clouds does not indicate a systematic instrument bias in either water vapor or temperature measurements in the upper troposphere.Furthermore, in situ measurements are compared to model data from the European Centre for Medium-Range Weather Forecasts (ECMWF) which are interpolated along the ML-CIRRUS flight tracks. We find a mean agreement within ±10% throughout the troposphere and a significant wet bias in the model on the order of 100% to 150% in the stratosphere close to 30 the tropopause. Consistent with previous studies, this analysis indicates that the model deficit is mainly caused by a blurred humidity gradient at tropopause altitudes.Atmos. Chem. Phys. Discuss., https://doi

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“…Finally, ref. [5] documents a relative expanded uncertainty of 4.3 % for an airborne laser hygrometer measuring water concentrations under field situations in the 20 mmol/mol to 600 μm/mol range. The laser hygrometer was validated against the German primary reference standard for humidity yielding relative deviations 2.5 % (Figure 2).…”

Section: Web Of Conferencesmentioning

confidence: 99%

“…A prerequisite for traceable measurements remains the availability of traceable line data (at least line strength ST). Measurement of line data is our first step to achieve traceability while working with commercial instruments TDLAS hygrometer and PTB's primary reference humidity generator (PHG) [5].…”

Section: Crds and Pasmentioning

confidence: 99%

“…We developed absolute laser hygrometers which are used in atmospheric research [5], combustion research [6,7], or to measure humidity in natural gas or biogas for quality assurance purposes [8]. In the framework of the completed EMRP project MacPoll [9] we developed an absolute spectrometer targeting CO2 and H2O to DOI: 10.1051/ C Owned by the authors, published by EDP Sciences, 2015 2015 m 0 00 etrolo / gy validate the CO2 concentration and humidity in zero gas which is used to check the zero-reading of calibrated sensors and as dilution gas for reference gas mixtures [10].…”

Section: Introductionmentioning

confidence: 99%

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Traceable amount of substance fraction measurements in gases through infrared spectroscopy at PTB

Lüttschwager

Pogány

Nwaboh

et al. 2015

17th International Congress of Metrology

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Abstract. Gas analysis has become an important task in various fields of science and industry, especially through techniques based on laser spectroscopy. Common applications are, for example, the monitoring of the atmosphere to assess human impact on ecosystems and the climate, the monitoring of airborne molecular contamination to supervise sensitive high-tech processes like semiconductor manufacturing, or the analysis of combustion processes. High resolution laser spectroscopy lends itself particularly well for gas analysis, as it is fast, selective, and the results can be made traceable to the SI units. Traceability is of particular importance to maximize the reliability of measurement results, especially if such measurements are the input for complicated models like those used in climate research or if impacting political decisions. In this contribution we give an overview on our approach to achieve traceability of results from spectroscopic amount fraction measurements of H2O, CO2, and NH3 including the TILSAM method (traceable infrared laser-spectrometric amount fraction measurement). We discuss how this method applies to tunable diode-laser absorption spectroscopy (TDLAS), cavity ring-down spectroscopy (CRDS), and photoacoustic spectroscopy (PAS). This research is partly embedded in projects within the European Metrology Research Programme (EMRP).

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Absolute validation of a diode laser hygrometer via intercomparison with the German national primary water vapor standard

Cited by 74 publications

References 54 publications

Metrology for ammonia in ambient air – concept and first results of the EMRP project MetNH3

Metrology for ammonia in ambient air – concept and first results of the EMRP project MetNH3

Intercomparison of mid-latitude tropospheric and lower stratospheric water vapor measurements and comparison to ECMWF humidity data

Traceable amount of substance fraction measurements in gases through infrared spectroscopy at PTB

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