Long‐term trend analysis of aerosol variables at the high‐alpine site Jungfraujoch

Coen, Martine Collaud; Weingärtner, E.; Nyeki, S.; Cozic, J.; Henning, S.; Verheggen, B.; Gehrig, Robert; Baltensperger, Urs

doi:10.1029/2006jd007995

Cited by 103 publications

(92 citation statements)

References 38 publications

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“…The Jungfraujoch (JFJ) measurement site is a Global Atmosphere Watch (GAW) station where different aerosol properties have been continuously measured since 1995 (Nyeki et al, 1998;Collaud Coen et al, 2007). The site is situated in the Bernese Alps in Switzerland at 3580 m a.s.l.…”

Section: Methodsmentioning

confidence: 99%

Measured and modelled cloud condensation nuclei number concentration at the high alpine site Jungfraujoch

et al. 2010

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Abstract. Atmospheric aerosol particles are able to act as cloud condensation nuclei (CCN) and are therefore important for the climate and the hydrological cycle, but their properties are not fully understood. Total CCN number concentrations at 10 different supersaturations in the range of SS = 0.12-1.18% were measured in May 2008 at the remote high alpine research station, Jungfraujoch, Switzerland (3580 m a.s.l.). In this paper, we present a closure study between measured and predicted CCN number concentrations. CCN predictions were done using dry number size distribution (scanning particle mobility sizer, SMPS) and bulk chemical composition data (aerosol mass spectrometer, AMS, and multi-angle absorption photometer, MAAP) in a simplified Köhler theory. The predicted and the measured CCN number concentrations agree very well and are highly correlated. A sensitivity study showed that the temporal variability of the chemical composition at the Jungfraujoch can be neglected for a reliable CCN prediction, whereas it is important to know the mean chemical composition. The exact bias introduced by using a too low or too high hygroscopicity parameter for CCN prediction was further quantified and shown to be substantial for the lowest supersaturation.Despite the high average organic mass fraction (∼45%) in the fine mode, there was no indication that the surface tension was substantially reduced at the point of CCN activation. A comparison between hygroscopicity tandem differential mobility analyzer (HTDMA), AMS/MAAP, and CCN derived κ values showed that HTDMA measurements can be used to determine particle hygroscopicity required for CCN predictions if no suitable chemical composition data are available.

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Section: Methodsmentioning

confidence: 99%

Measured and modelled cloud condensation nuclei number concentration at the high alpine site Jungfraujoch

et al. 2010

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“…Mertes et al, 2007;Verheggen et al, 2007;Cozic et al, 2008;Targino et al, 2009;Kamphus et al, 2010;Zieger et al, 2012). The aerosol measurements performed at the JFJ are part of the Global Atmosphere Watch (GAW) program of the World Meteorological Organization since 1995 (Collaud Coen et al, 2007). Long term studies have been conducted at the site, which indicated that the station is in clouds approximately 40 % of the time throughout the year (Baltensperger et al, 1998).…”

Section: Instrumentation and Sitementioning

confidence: 99%

Evaluating the capabilities and uncertainties of droplet measurements for the fog droplet spectrometer (FM-100)

Spiegel¹,

Zieger²,

Bukowiecki³

et al. 2012

Atmos. Meas. Tech.

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Abstract. Droplet size spectra measurements are crucial to obtain a quantitative microphysical description of clouds and fog. However, cloud droplet size measurements are subject to various uncertainties. This work focuses on the error analysis of two key measurement uncertainties arising during cloud droplet size measurements with a conventional droplet size spectrometer (FM-100): first, we addressed the precision with which droplets can be sized with the FM-100 on the basis of the Mie theory. We deduced error assumptions and proposed a new method on how to correct measured size distributions for these errors by redistributing the measured droplet size distribution using a stochastic approach. Second, based on a literature study, we summarized corrections for particle losses during sampling with the FM-100. We applied both corrections to cloud droplet size spectra measured at the high alpine site Jungfraujoch for a temperature range from 0 • C to 11 • C. We showed that Mie scattering led to spikes in the droplet size distributions using the default sizing procedure, while the new stochastic approach reproduced the ambient size distribution adequately. A detailed analysis of the FM-100 sampling efficiency revealed that particle losses were typically below 10 % for droplet diameters up to 10 µm. For larger droplets, particle losses can increase up to 90 % for the largest droplets of 50 µm at ambient wind speeds below 4.4 m s −1 and even to >90 % for larger angles between the instrument orientation and the wind vector (sampling angle) at higher wind speeds. Comparisons of the FM-100 to other reference instruments revealed that the total liquid water content (LWC) measured by the FM-100 was more sensitive to particle losses than to re-sizing based on Mie scattering, while the total number concentration was only marginally influenced by particle losses. Consequently, for further LWC measurements with the FM-100 we strongly recommend to consider (1) the error arising due to Mie scattering, and (2) the particle losses, especially for larger droplets depending on the set-up and wind conditions.

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“…at the Jungfraujoch (JFJ) in the Swiss Alps at 7 • 59 2 E, 46 • 32 53 N. During the winter months it is located in the free troposphere without regular injections from the planetary boundary layer (Coen et al, 2007) and it is frequently surrounded by mixed-phase clouds. The intensive measurement period of the Cloud and Aerosol Characterization Experiment 6 (CLACE 6) took place from 17 February to 14 March 2007.…”

Section: Sphinx Laboratory At the Jungfraujochmentioning

confidence: 99%

Chemical composition of ambient aerosol, ice residues and cloud droplet residues in mixed-phase clouds: single particle analysis during the Cloud and Aerosol Characterization Experiment (CLACE 6)

et al. 2010

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Abstract. Two different single particle mass spectrometers were operated in parallel at the Swiss High Alpine Research Station Jungfraujoch (JFJ, 3580 m a.s.l.) during the Cloud and Aerosol Characterization Experiment (CLACE 6) in February and March 2007. During mixed phase cloud events ice crystals from 5-20 µm were separated from larger ice aggregates, non-activated, interstitial aerosol particles and supercooled droplets using an Ice-Counterflow Virtual Impactor (Ice-CVI). During one cloud period supercooled droplets were additionally sampled and analyzed by changing the Ice-CVI setup. The small ice particles and droplets were evaporated by injection into dry air inside the Ice-CVI. The resulting ice and droplet residues (IR and DR) were analyzed for size and composition by the two single particle mass spectrometers: a custom-built Single Particle Laser-Ablation Time-of-Flight Mass Spectrometer (SPLAT) and a commercial Aerosol Time-of-Flight Mass Spectrometer (ATOFMS, TSI Model 3800). During CLACE 6 the SPLAT instrument characterized 355 individual IR that produced a mass spectrum for at least one polarity and the ATOFMS measured 152 IR. The mass spectra were binned Correspondence to: J. Curtius (curtius@iau.uni-frankfurt.de) in classes, based on the combination of dominating substances, such as mineral dust, sulfate, potassium and elemental carbon or organic material. The derived chemical information from the ice residues is compared to the JFJ ambient aerosol that was sampled while the measurement station was out of clouds (several thousand particles analyzed by SPLAT and ATOFMS) and to the composition of the residues of supercooled cloud droplets (SPLAT: 162 cloud droplet residues analyzed, ATOFMS: 1094). The measurements showed that mineral dust was strongly enhanced in the ice particle residues. Close to all of the SPLAT spectra from ice residues did contain signatures from mineral compounds, albeit connected with varying amounts of soluble compounds. Similarly, close to all of the ATOFMS IR spectra show a mineral or metallic component. Pure sulfate and nitrate containing particles were depleted in the ice residues. Sulfate and nitrate was found to dominate the droplet residues (∼90% of the particles). The results from the two different single particle mass spectrometers were generally in agreement. Differences in the results originate from several causes, such as the different wavelength of the desorption and ionisation lasers and different size-dependent particle detection efficiencies.

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Long‐term trend analysis of aerosol variables at the high‐alpine site Jungfraujoch

Cited by 103 publications

References 38 publications

Measured and modelled cloud condensation nuclei number concentration at the high alpine site Jungfraujoch

Measured and modelled cloud condensation nuclei number concentration at the high alpine site Jungfraujoch

Evaluating the capabilities and uncertainties of droplet measurements for the fog droplet spectrometer (FM-100)

Chemical composition of ambient aerosol, ice residues and cloud droplet residues in mixed-phase clouds: single particle analysis during the Cloud and Aerosol Characterization Experiment (CLACE 6)

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