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  • 1
    Online Resource
    Online Resource
    Upper-tropospheric slightly ice-subsaturated regions: frequency of occurrence and statistical evidence for the appearance of contrail cirrus
    Copernicus GmbH ; 2023
    In:  Atmospheric Chemistry and Physics Vol. 23, No. 3 ( 2023-02-16), p. 2251-2271
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 23, No. 3 ( 2023-02-16), p. 2251-2271
    Abstract: Abstract. Microphysical, optical, and environmental properties of contrail cirrus and natural cirrus were investigated by applying a new, statistically based contrail–cirrus separation method to 14.7 h of cirrus cloud measurements (sampling frequency 1 Hz, max. ∼ 290 m s−1, total length of sampled in-cloud space ∼ 15 000 km) during the airborne campaign ML-CIRRUS in central Europe and the northeast Atlantic flight corridor in spring 2014. We find that pure contrail cirrus appears frequently at the aircraft cruising altitude (CA) range with ambient pressure varying from 200 to 245 hPa. It exhibits a higher median ice particle number concentration (Nice), a smaller median mass mean radius (Rice), and lower median ice water content (IWC) (median: Nice=0.045 cm−3, Rice=16.6 µm, IWC = 3.5 ppmv), and it is optically thinner (median extinction coefficient Ext = ∼ 0.056 km−1) than the cirrus mixture of contrail cirrus, natural in situ-origin and liquid-origin cirrus found around the CA range (median: Nice=0.038 cm−3, Rice=24.1 µm, IWC = 8.3 ppmv, Ext = ∼ 0.096 km−1). The lowest and thickest cirrus, consisting of a few large ice particles, are identified as pure natural liquid-origin cirrus (median: Nice=0.018 cm−3, Rice=42.4 µm, IWC = 21.7 ppmv, Ext = ∼ 0.137 km−1). Furthermore, we observe that, in particular, contrail cirrus occurs more often in slightly ice-subsaturated instead of merely ice-saturated to supersaturated air as often assumed, thus indicating the possibility of enlarged contrail cirrus existence regions. The enlargement is estimated, based on IAGOS long-term observations of relative humidity with respect to ice (RHice) aboard passenger aircraft, to be approximately 10 % for Europe and the North Atlantic region, with the RHice threshold for contrail cirrus existence decreased from 100 % to 90 % RHice and a 4 h lifetime of contrail cirrus in slight ice subsaturation assumed. This increase may not only lead to a non-negligible change in contrail cirrus coverage and radiative forcing, but also affect the mitigation strategies of reducing contrails by rerouting flights.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    URL: Article
    DOI: 10.5194/acp-23-2251-2023
    DOI: 10.5194/acp-23-2251-2023-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2023
    detail.hit.zdb_id: 2092549-9
    detail.hit.zdb_id: 2069847-1
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  • 2
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    Online Resource
    The IAGOS NO〈sub〉〈i〉x〈/i〉〈/sub〉 instrument – design, operation and first results from deployment aboard passenger aircraft
    Copernicus GmbH ; 2018
    In:  Atmospheric Measurement Techniques Vol. 11, No. 6 ( 2018-06-27), p. 3737-3757
    Details
    In: Atmospheric Measurement Techniques, Copernicus GmbH, Vol. 11, No. 6 ( 2018-06-27), p. 3737-3757
    Abstract: Abstract. We describe the nitrogen oxide instrument designed for the autonomous operation on board passenger aircraft in the framework of the European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System). We demonstrate the performance of the instrument using data from two deployment periods aboard an A340-300 aircraft of Deutsche Lufthansa. The well-established chemiluminescence detection method is used to measure nitrogen monoxide (NO) and nitrogen oxides (NOx). NOx is measured using a photolytic converter, and nitrogen dioxide (NO2) is determined from the difference between NOx and NO. This technique allows measuring at high time resolution (4 s) and high precision in the low ppt range (NO: 2σ = 24 pptv; NOx: 2σ = 35 pptv) over different ambient temperature and ambient pressure altitude ranges (from surface pressure down to 190 hPa). The IAGOS NOx instrument is characterized for (1) calibration stability and total uncertainty, (2) humidity and chemical interferences (e.g., ozone; nitrous acid, HONO; peroxyacetyl nitrate, PAN) and (3) inter-instrumental precision. We demonstrate that the IAGOS NOx instrument is a robust, fully automated, and long-term stable instrument suitable for unattended operation on airborne platforms, which provides useful measurements for future air quality studies and emission estimates.
    Type of Medium: Online Resource
    ISSN: 1867-8548
    URL: Article
    URL: Article
    DOI: 10.5194/amt-11-3737-2018
    DOI: 10.5194/amt-11-3737-2018-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2018
    detail.hit.zdb_id: 2505596-3
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  • 3
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    Online Resource
    Characterisation of a self-sustained, water-based condensation particle counter for aircraft cruising pressure level operation
    Copernicus GmbH ; 2023
    In:  Atmospheric Measurement Techniques Vol. 16, No. 14 ( 2023-07-21), p. 3505-3514
    Details
    In: Atmospheric Measurement Techniques, Copernicus GmbH, Vol. 16, No. 14 ( 2023-07-21), p. 3505-3514
    Abstract: Abstract. Aerosol particle number concentration measurements are a crucial part of aerosol research. Vertical profile measurements and high-altitude/low-pressure performance of the respective instruments become more important for remote sensing validation and a vital tool for the observation of climate variables. This study tests the new, commercially available water condensation particle counter (MAGIC 210-LP) for the deployment at aircraft cruising pressure levels that the European research infrastructure IAGOS (In-service Aircraft for a Global Observing System; http://www.iagos.org, last access: 2 May 2023) is aiming for by operating measurement instrumentation onboard passenger aircraft. We conducted laboratory experiments for conditions to simulate passenger aircraft flight altitude at operation pressure. We demonstrate that this type of water condensation particle counter shows excellent agreement with a butanol-based instrument used in parallel. A Faraday cup aerosol electrometer serves as the reference instrument. Experiments are performed with test aerosol ammonium sulfate and fresh combustion soot at pressure levels ranging from 700 to 200 hPa. For soluble particles like ammonium sulfate, the 50 % detection efficiency cut-off diameter (D50) is around 5 nm and does not differ significantly for all performed experiments. For non-soluble fresh soot particles, the D50 cut-off diameter of approximately 10 nm does not vary substantially as a function of pressure, whereas the 90 % detection efficiency cut-off diameter D90 increases from 19 nm at 700 hPa to 37 nm at 200 hPa. The overall counting efficiency for particles larger than 40 nm reaches 100 % for working pressures of 200 hPa and higher.
    Type of Medium: Online Resource
    ISSN: 1867-8548
    URL: Article
    URL: Article
    DOI: 10.5194/amt-16-3505-2023
    DOI: 10.5194/amt-16-3505-2023-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2023
    detail.hit.zdb_id: 2505596-3
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  • 4
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    Online Resource
    Relative errors in derived multi-wavelength intensive aerosol optical properties using cavity attenuated phase shift single-scattering albedo monitors, a nephelometer, and tricolour absorption photometer measurements
    Copernicus GmbH ; 2022
    In:  Atmospheric Measurement Techniques Vol. 15, No. 11 ( 2022-06-02), p. 3279-3296
    Details
    In: Atmospheric Measurement Techniques, Copernicus GmbH, Vol. 15, No. 11 ( 2022-06-02), p. 3279-3296
    Abstract: Abstract. Aerosol intensive optical properties, including Ångström exponents for aerosol light extinction (EAEs), scattering (SAEs) and absorption (AAEs) as well as and the single-scattering albedo (SSA), are indicators for aerosol size, chemical composition, radiative behaviour and particle sources. Derivation of these parameters requires the measurement of aerosol optical properties at multiple wavelengths, which usually involves the use of several instruments. Our study aims to quantify the uncertainties in the determination of these intensive properties using an optical closure approach. In our laboratory closure study, we measured the full set of optical properties for a range of light-absorbing particles with different properties externally mixed with ammonium sulfate to generate aerosols with controlled SSA values. The investigated absorbing particle types were fresh combustion soot emitted by an inverted flame soot generator (SOOT; fractal agglomerates), Aquadag (AQ; compact aggregates), Cabot black (BC; compact agglomerates) and an acrylic paint (magic black, shape unknown). The instruments used in this study were two cavity attenuated phase shift particle monitors for single-scattering albedo (CAPS PMSSA's; λ=450, 630 nm) for measuring light-extinction and light-scattering coefficients, one integrating nephelometer (λ=450, 550, 700 nm) for light-scattering coefficients, and one tricolour absorption photometer (TAP; λ=467, 528, 652 nm) for filter-based light-absorption coefficients. One key finding is that the coefficients of light absorption, scattering and extinction derived from combing the measurements of two independent instruments agree with measurements from single instruments; the slopes of regression lines are equal within reported uncertainties (i.e. closure is observed). Despite closure for measured absorption coefficients, we caution that the estimated uncertainties for absorption coefficients, propagated for the differential method (DM; absorption = extinction minus scattering), can exceed 100 % for atmospherically relevant SSA values (〉0.9). This increasing estimated uncertainty with increasing SSA yields AAE values that may be too uncertain for measurements in the range of atmospheric aerosol loadings. We recommend using the DM for measuring AAE values when the SSA 〈 0.9. EAE- and SAE-derived values achieved closure during this study within stated uncertainties for extinction coefficients greater than 15 Mm−1. SSA values for 450 and 630 nm wavelengths internally agreed with each other within 10 % uncertainty for all instrument combinations and sampled aerosol types, which fulfils the defined goals for measurement uncertainty of 10 % proposed by Laj et al. (2020) for GCOS (Global Climate Observing System) applications.
    Type of Medium: Online Resource
    ISSN: 1867-8548
    URL: Article
    DOI: 10.5194/amt-15-3279-2022
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2022
    detail.hit.zdb_id: 2505596-3
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  • 5
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    Online Resource
    In situ temperature measurements in the upper troposphere and lowermost stratosphere from 2 decades of IAGOS long-term routine observation
    Copernicus GmbH ; 2017
    In:  Atmospheric Chemistry and Physics Vol. 17, No. 20 ( 2017-10-23), p. 12495-12508
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 17, No. 20 ( 2017-10-23), p. 12495-12508
    Abstract: Abstract. Despite several studies on temperature trends in the tropopause region, a comprehensive understanding of the evolution of temperatures in this climate-sensitive region of the atmosphere remains elusive. Here we present a unique global-scale, long-term data set of high-resolution in situ temperature data measured aboard passenger aircraft within the European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System; http://www.iagos.org). This data set is used to investigate temperature trends within the global upper troposphere and lowermost stratosphere (UTLS,  〈  13 km) for the period of 1995–2012 in different geographical regions and vertical layers of the UTLS. The largest number of observations is available over the North Atlantic. Here, a neutral temperature trend is found within the lowermost stratosphere. This contradicts the temperature trend in the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis, in which a significant (95 % confidence) temperature increase of +0.56 K decade−1 is found. Differences between trends derived from observations and reanalysis data can be traced back to changes in the temperature difference between observation and model data over the period studied. This study underpins the value of the IAGOS temperature observations as an anchor point for the evaluation of reanalyses and its suitability for independent trend analyses.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    URL: Article
    DOI: 10.5194/acp-17-12495-2017
    DOI: 10.5194/acp-17-12495-2017-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2017
    detail.hit.zdb_id: 2092549-9
    detail.hit.zdb_id: 2069847-1
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  • 6
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    A new working fluid for condensation particle counters for use in sensitive working environments
    Copernicus GmbH ; 2023
    In:  Aerosol Research Vol. 1, No. 1 ( 2023-06-27), p. 1-12
    Details
    In: Aerosol Research, Copernicus GmbH, Vol. 1, No. 1 ( 2023-06-27), p. 1-12
    Abstract: Abstract. The working fluid of a condensation particle counter (CPC) is one of its essential characteristics. Butanol is commonly used as the working fluid in alcohol-based CPCs due to its proven performance for various applications and for a wide range of working conditions over the past almost 5 decades. At the same time, butanol has several disadvantages, including its strong and unpleasant odour, negative effects when inhaled over prolonged periods and flammability, making it troublesome to use in places with strict safety regulations. In this work, we propose addressing these negative issues by replacing butanol with dimethyl sulfoxide (DMSO), a substance that has not been used as a CPC working fluid to date. DMSO is an odourless, non-flammable and non-toxic substance that is easily accessible and inexpensive. During thorough experiments, this new substitute working fluid has proven to be stable with respect to its performance for CPCs and storage. We show that DMSO behaves in an equivalent manner to butanol when used to operate a CPC in terms of the instrument's counting efficiency, D50 cut-off diameter (the diameter at which 50 % of the particles are counted with respect to a reference) and concentration linearity. In addition, we have demonstrated this for operating pressures ranging from ambient pressure down to 200 hPa without the need for any safety precautions. Our new working fluid was tested on three CPC units representing two different models, almost always in side-by-side measurements. So far, we have achieved the best results with operating temperatures of 40 ∘C for the CPC's saturator and 5 ∘C for its condenser. To address a less desirable property of DMSO, it could be mixed with a slight amount of water to decrease its freezing point significantly. When mixed accordingly, the substance remains a liquid, even in work environments with temperatures ≤ −10 ∘C, without any impact on the CPC's counting efficiency performance.
    Type of Medium: Online Resource
    ISSN: 2940-3391
    URL: Article
    DOI: 10.5194/ar-1-1-2023
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2023
    detail.hit.zdb_id: 3142621-9
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  • 7
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    Online Resource
    Evaluation of modelled climatologies of O 3 , CO, water vapour and NO y in the upper troposphere–lower stratosphere using regular in situ observations by passenger aircraft
    Copernicus GmbH ; 2023
    In:  Atmospheric Chemistry and Physics Vol. 23, No. 23 ( 2023-12-06), p. 14973-15009
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 23, No. 23 ( 2023-12-06), p. 14973-15009
    Abstract: Abstract. Evaluating global chemistry models in the upper troposphere–lower stratosphere (UTLS) is an important step toward an improved understanding of the chemical composition in this region. This composition is regularly sampled through in situ measurements based on passenger aircraft, in the framework of the In-service Aircraft for a Global Observing System (IAGOS) research infrastructure. This study focuses on the comparison of the IAGOS measurements in ozone, carbon monoxide (CO), nitrogen reactive species (NOy) and water vapour, with a 25-year simulation output from the LMDZ-OR-INCA chemistry–climate model. For this purpose, we present and apply an extension of the Interpol-IAGOS software that projects the IAGOS data onto any model grid, in order to derive a gridded IAGOS product and a masked (sub-sampled) model product that are directly comparable to one another. Climatologies are calculated in the upper troposphere (UT) and in the lower stratosphere (LS) separately but also in the UTLS as a whole, as a demonstration for the models that do not sort out the physical variables necessary to distinguish between the UT and the LS. In the northern extratropics, the comparison in the UTLS layer suggests that the geographical distribution in the tropopause height is well reproduced by the model. In the separated layers, the model simulates well the water vapour climatologies in the UT and the ozone climatologies in the LS. There are opposite biases in CO in both UT and LS, which suggests that the cross-tropopause transport is overestimated. The NOy observations highlight the difficulty of the model in parameterizing the lightning emissions. In the tropics, the upper-tropospheric climatologies are remarkably well simulated for water vapour. They also show realistic CO peaks due to biomass burning in the most convective systems, and the ozone latitudinal variations are well correlated between the observations and the model. Ozone is more sensitive to lightning emissions than to biomass burning emissions, whereas the CO sensitivity to biomass burning emissions strongly depends on location and season. The present study demonstrates that the Interpol-IAGOS software is a tool facilitating the assessment of global model simulations in the UTLS, which is potentially useful for any modelling experiment involving chemistry climate or chemistry transport models.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    URL: Article
    DOI: 10.5194/acp-23-14973-2023
    DOI: 10.5194/acp-23-14973-2023-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2023
    detail.hit.zdb_id: 2069847-1
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  • 8
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    Online Resource
    Quality assessment of MOZAIC and IAGOS capacitive hygrometers: insights from airborne field studies
    Stockholm University Press ; 2015
    In:  Tellus B: Chemical and Physical Meteorology Vol. 67, No. 1 ( 2015-01-01), p. 28320-
    Details
    In: Tellus B: Chemical and Physical Meteorology, Stockholm University Press, Vol. 67, No. 1 ( 2015-01-01), p. 28320-
    Type of Medium: Online Resource
    ISSN: 1600-0889 , 0280-6509
    URL: Article
    DOI: 10.3402/tellusb.v67.28320
    RVK:
    RA 1000
    RVK:
    UA 8382.2
    Language: Unknown
    Publisher: Stockholm University Press
    Publication Date: 2015
    detail.hit.zdb_id: 2026992-4
    detail.hit.zdb_id: 246061-0
    SSG: 16,13
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  • 9
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    Online Resource
    Chemical composition and complex refractive index of Saharan Mineral Dust at Izaña, Tenerife (Spain) derived by electron microscopy
    Elsevier BV ; 2007
    In:  Atmospheric Environment Vol. 41, No. 37 ( 2007-12), p. 8058-8074
    Details
    In: Atmospheric Environment, Elsevier BV, Vol. 41, No. 37 ( 2007-12), p. 8058-8074
    Type of Medium: Online Resource
    ISSN: 1352-2310
    URL: Article
    DOI: 10.1016/j.atmosenv.2007.06.047
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2007
    detail.hit.zdb_id: 216368-8
    detail.hit.zdb_id: 1499889-0
    SSG: 14
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  • 10
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    Online Resource
    Laboratory validation of a compact single-scattering albedo (SSA) monitor
    Copernicus GmbH ; 2021
    In:  Atmospheric Measurement Techniques Vol. 14, No. 2 ( 2021-03-01), p. 1635-1653
    Details
    In: Atmospheric Measurement Techniques, Copernicus GmbH, Vol. 14, No. 2 ( 2021-03-01), p. 1635-1653
    Abstract: Abstract. An evaluation of the performance and relative accuracy of a Cavity Attenuated Phase-Shift Single Scattering Albedo Monitor (CAPS PMSSA; Aerodyne Research, Inc.) was conducted in an optical-closure study with proven technologies: Cavity Attenuated Phase-Shift Particle Extinction Monitor (CAPS PMex; Aerodyne Research, Inc.), three-wavelength integrating nephelometer (TSI Model 3563) and three-wavelength filter-based Particle Soot Absorption Photometer (PSAP; Radiance Research Inc.). The evaluation was conducted by connecting the instruments to a controlled aerosol generation system and comparing the measured scattering, extinction and absorption coefficients measured by the CAPS PMSSA with the independent measurements. Three different particle types were used to generate aerosol samples with single-scattering albedos (SSAs) ranging from 0.4 to 1.0 at 630 nm wavelength. The CAPS PMSSA measurements compared well with the proven technologies. Extinction measurement comparisons exhibited a slope of the linear regression line for the full dataset between 1.05 and 1.01, an intercept below ±1.5×10-6 m−1 (±1.5 Mm−1), and a regression coefficient R2〉0.99, whereas scattering measurements had a slope between 0.90 and 1.04, an intercept of less than ±2.0×10-6 m−1 (2.0 Mm−1), and a coefficient R2〉0.96. The derived CAPS PMSSA absorption compared well to the PSAP measurements for the small particle sizes and modest (0.4 to 0.6) SSA values tested, with a linear regression slope between 0.90 and 1.07, an intercept of ±3.0×10-6 m−1 (3.0 Mm−1), and a coefficient R2〉0.99. For the SSA measurements, agreement was highest (regression slopes within 1 %) for SSA =1.0 particles at extinction levels of per tens of inverse megameters and above; however, as extinctions approach 0, small uncertainties in the baseline can introduce larger errors. SSA measurements for absorbing particles exhibited absolute differences up to 18 %, though it is not clear which measurement had the best relative accuracy. For a given particle type, the CAPS PMSSA instrument exhibited the lowest scatter around the average. This study demonstrates that the CAPS PMSSA is a robust and reliable instrument for the direct measurement of the scattering and extinction coefficients and thus SSA. This conclusion also holds for the indirect measurement of the absorption coefficient with the constraint that the relative accuracy of this particular determination degrades as the SSA and particle size increases.
    Type of Medium: Online Resource
    ISSN: 1867-8548
    URL: Article
    DOI: 10.5194/amt-14-1635-2021
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2021
    detail.hit.zdb_id: 2505596-3
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