Technical Note: Reanalysis of upper troposphere humidity data from the MOZAIC programme for the period 1994 to 2009

Smit, H. G. J.; Rohs, Susanne; Neis, Patrick; Boulanger, Damien; Krämer, M.; Wahner, Andreas; Petzold, A.

doi:10.5194/acp-14-13241-2014

Cited by 27 publications

(36 citation statements)

References 47 publications

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“…The RH liquid flight data of the MCH obtained during the CIRRUS-III campaign were corrected for this offset drift. The resulting overall uncertainty of the RH measurements by the MCH, including contributions from temperature uncertainties, is about ±5 % RH liquid , which is in good agreement with the mean uncertainty range obtained from long-term MOZAIC measurements (Smit et al, 2014) .…”

Section: Instrumentationsupporting

confidence: 71%

“…A detailed description of the MOZAIC Capacitive Hygrometer is given by Helten et al (1998Helten et al ( , 1999 and Smit et al (2014). In the following, we summarise the original descriptions.…”

Section: Mozaic Capacitive Hygrometermentioning

confidence: 99%

“…The first validation studies from formation flights of a MOZAIC aircraft and a research aircraft are reported by Helten et al (1999), while Smit et al (2008) present an approach for a potential in-flight calibration of the MCH. A reanalysis of the global MOZAIC RH data set for the period 2000-2009 was performed recently (Smit et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the MOZAIC Capacitive Hygrometer during the airborne field study CIRRUS-III

Neis

Smit²,

Krämer³

et al. 2015

Atmos. Meas. Tech.

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Abstract. The MOZAIC Capacitive Hygrometer (MCH) is usually operated aboard passenger aircraft in the framework of MOZAIC (Measurement of Ozone by Airbus In-Service Aircraft) for measuring atmospheric relative humidity (RH). In order to evaluate the performance of the MCH, the instrument was operated aboard a Learjet 35A research aircraft as part of the CIRRUS-III field study together with a closed-cell Lyman-α fluorescence hygrometer (Fast in situ Stratospheric Hygrometer, or FISH) and an open-path tunable diode laser system (Open-path Jülich Stratospheric TDL ExpeRiment, or OJSTER) for water vapour measurement. After reducing the CIRRUS-III data set to data corresponding to MOZAIC aircraft operation conditions, the 1 Hz RH data cross correlation between the MCH and reference instruments FISH (clear sky) and OJSTER (in-cirrus) yielded a remarkably good agreement of R 2 = 0.92 and slope m = 1.02 and provided a MCH uncertainty of 5 % RH. Probability distribution functions of RH deduced from the MCH and reference instruments agreed well between 10 and 70 % RH with respect to liquid water in the ambient temperature range of ca.−70 to −40 • C. The use of MCH data is limited to sensor temperatures above the calibration limit of T sensor = −40 • C (corresponds to ambient temperature of T ambient = −70 • C at typical cruising speed of long-haul passenger aircraft). Good performance of the MCH for clear sky as well as for in-cirrus conditions demonstrated the sensor robustness also for operation inside ice clouds.

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Section: Instrumentationsupporting

confidence: 71%

Section: Mozaic Capacitive Hygrometermentioning

confidence: 99%

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Evaluation of the MOZAIC Capacitive Hygrometer during the airborne field study CIRRUS-III

Neis

Smit²,

Krämer³

et al. 2015

Atmos. Meas. Tech.

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“…A detailed description and evaluation of the MOZAIC Capacitive Hygrometer is given elsewhere (Helten et al, , 1999Smit et al, 2014;Neis et al, 2015). The ICH uses a capacitive sensor (Vaisala HUMICAP † of type H, Finland), the capacitance of which depends on the RH of the dielectric layer of the condenser, and a platinum resistance sensor (Pt100) for the direct measurement of the temperature at the humidity sensing surface.…”

Section: Description Of the Modified Iagos Capacitive Hygrometermentioning

confidence: 99%

“…Gierens et al, 2000;Spichtinger et al, 2003) in the upper troposphere. The reanalysis of the global MOZAIC RH data set for the period 2000Á2009 was recently published (Smit et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Quality assessment of MOZAIC and IAGOS capacitive hygrometers: insights from airborne field studies

Neis

Smit²,

Rohs³

et al. 2015

Tellus B: Chemical and Physical Meteorology

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A B S T R A C TIn 2011, the MOZAIC (Measurement of Ozone by AIRBUS In-Service Aircraft) successor programme IAGOS (In-service Aircraft for a Global Observing System) started to equip their long-haul passenger aircraft with the modified capacitive hygrometer Vaisala HUMICAP † of type H. The assurance of the data quality and the consistency of the data set during the transition from MOZAIC Capacitive Hygrometers to IAGOS Capacitive Hygrometers were evaluated within the CIRRUS-III and AIRTOSS-ICE field studies. During these performance tests, the capacitive hygrometers were operated aboard a Learjet 35A aircraft together with a closedcell Lyman-a fluorescence hygrometer, an open-path tunable diode laser (TDL) system and a closed-cell, direct TDL absorption hygrometer for water vapour measurement. For MOZAIC-typical operation conditions, the comparison of relative humidity (RH) data from the capacitive hygrometers and reference instruments yielded remarkably good agreement with an uncertainty of 5% RH. The temperature dependence of the sensor's response time was derived from the cross-correlation of capacitive hygrometer data and smoothed data from the fast-responding reference instruments. The resulting exponential moving average function could explain the major part of the observed deviations between the capacitive hygrometers and the reference instruments.

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The need for accurate long‐term measurements of water vapor in the upper troposphere and lower stratosphere with global coverage

et al. 2016

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Water vapor is the most important greenhouse gas in the atmosphere although changes in carbon dioxide constitute the “control knob” for surface temperatures. While the latter fact is well recognized, resulting in extensive space-borne and ground-based measurement programs for carbon dioxide as detailed in the studies by Keeling et al. (1996), Kuze et al. (2009), and Liu et al. (2014), the need for an accurate characterization of the long-term changes in upper tropospheric and lower stratospheric (UTLS) water vapor has not yet resulted in sufficiently extensive long-term international measurement programs (although first steps have been taken). Here, we argue for the implementation of a long-term balloon-borne measurement program for UTLS water vapor covering the entire globe that will likely have to be sustained for hundreds of years.

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Technical Note: Reanalysis of upper troposphere humidity data from the MOZAIC programme for the period 1994 to 2009

Cited by 27 publications

References 47 publications

Evaluation of the MOZAIC Capacitive Hygrometer during the airborne field study CIRRUS-III

Evaluation of the MOZAIC Capacitive Hygrometer during the airborne field study CIRRUS-III

Quality assessment of MOZAIC and IAGOS capacitive hygrometers: insights from airborne field studies

The need for accurate long‐term measurements of water vapor in the upper troposphere and lower stratosphere with global coverage

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