Absolute, pressure-dependent validation of a calibration-free, airborne laser hygrometer transfer standard (SEALDH-II) from 5 to 1200 ppmv using a metrological humidity generator

• Verfasst von: Buchholz, Bernhard [VerfasserIn]
• Verfasst von: Ebert, Volker [VerfasserIn]
• Titel: Absolute, pressure-dependent validation of a calibration-free, airborne laser hygrometer transfer standard (SEALDH-II) from 5 to 1200 ppmv using a metrological humidity generator
• Verf.angabe: Bernhard Buchholz and Volker Ebert
• E-Jahr: 2018
• Jahr: 23 Jan 2018
• Umfang: 13 S.
• Fussnoten: Gesehen am 02.12.2020
• Titel Quelle: Enthalten in: Atmospheric measurement techniques
• Ort Quelle: Katlenburg-Lindau : Copernicus, 2008
• Jahr Quelle: 2018
• Band/Heft Quelle: 11(2018), 1, Seite 459-471
• ISSN Quelle: 1867-8548
• DOI: doi:10.5194/amt-11-459-2018
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1741700310

Abstract

<p><strong>Abstract.</strong> Highly accurate water vapor measurements are indispensable for understanding a variety of scientific questions as well as industrial processes. While in metrology water vapor concentrations can be defined, generated, and measured with relative uncertainties in the single percentage range, field-deployable airborne instruments deviate even under quasistatic laboratory conditions up to 10-20&thinsp;%. The novel SEALDH-II hygrometer, a calibration-free, tuneable diode laser spectrometer, bridges this gap by implementing a new holistic concept to achieve higher accuracy levels in the field. We present in this paper the absolute validation of SEALDH-II at a traceable humidity generator during 23 days of permanent operation at 15 different H<span class="inline-formula">₂</span>O mole fraction levels between 5 and 1200&thinsp;ppmv. At each mole fraction level, we studied the pressure dependence at six different gas pressures between 65 and 950&thinsp;hPa. Further, we describe the setup for this metrological validation, the challenges to overcome when assessing water vapor measurements on a high accuracy level, and the comparison results. With this validation, SEALDH-II is the first airborne, metrologically validated humidity transfer standard which links several scientific airborne and laboratory measurement campaigns to the international metrological water vapor scale.</p>