Characterisation of the filter inlet system on the BAE-146 research aircraft and its use for size resolved aerosol composition measurements

Sanchez-Marroquín, Alberto; Hedges, Duncan H. P.; Hiscock, Matthew; Parker, Simon; Rosenberg, Phil; Trembath, Jamie; Walshaw, Richard; Burke, Ian T.; McQuaid, James B.; Murray, Benjamin J.

doi:10.5194/amt-2019-196

Cited by 5 publications

(10 citation statements)

References 19 publications

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“…lacking imperfections. However, quartz does have defects, albeit at a lower density than other minerals (Spencer and Smith, 1966). Quartz minerals can be subject to varying conditions and stresses after their formation and so the geological history of the quartz may also influence the degree of microtexture.…”

Section: Discussion Of the Nature Of Active Sites On Quartzmentioning

confidence: 99%

The ice-nucleating ability of quartz immersed in water and its atmospheric importance compared to K-feldspar

et al. 2019

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Abstract. Mineral dust particles are thought to be an important type of ice-nucleating particle (INP) in the mixed-phase cloud regime around the globe. While K-rich feldspar (K-feldspar) has been identified as being a particularly important component of mineral dust for ice nucleation, it has been shown that quartz is also relatively ice-nucleation active. Given quartz typically makes up a substantial proportion of atmospheric desert dust, it could potentially be important for cloud glaciation. Here, we survey the ice-nucleating ability of 10 α-quartz samples (the most common quartz polymorph) when immersed in microlitre supercooled water droplets. Despite all samples being α-quartz, the temperature at which they induce freezing varies by around 12 ∘C for a constant active site density. We find that some quartz samples are very sensitive to ageing in both aqueous suspension and air, resulting in a loss of ice-nucleating activity, while other samples are insensitive to exposure to air and water over many months. For example, the ice-nucleation temperatures for one quartz sample shift down by ∼2 ∘C in 1 h and 12 ∘C after 16 months in water. The sensitivity to water and air is perhaps surprising, as quartz is thought of as a chemically resistant mineral, but this observation suggests that the active sites responsible for nucleation are less stable than the bulk of the mineral. We find that the quartz group of minerals is generally less active than K-feldspars by roughly 7 ∘C, although the most active quartz samples are of a similar activity to some K-feldspars with an active site density, ns(T), of 1 cm−2 at −9 ∘C. We also find that the freshly milled quartz samples are generally more active by roughly 5 ∘C than the plagioclase feldspar group of minerals and the albite end member has an intermediate activity. Using both the new and literature data, active site density parameterizations have been proposed for freshly milled quartz, K-feldspar, plagioclase and albite. Combining these parameterizations with the typical atmospheric abundance of each mineral supports previous work that suggests that K-feldspar is the most important ice-nucleating mineral in airborne mineral dust.

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Section: Discussion Of the Nature Of Active Sites On Quartzmentioning

confidence: 99%

The ice-nucleating ability of quartz immersed in water and its atmospheric importance compared to K-feldspar

et al. 2019

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“…Further to the aerosol instrumentation, several filter samples were taken in parallel to those collected for INP measurements so that scanning electron microscopy (SEM) could then be employed to obtain chemical composition and size distributions of the aerosol particles trapped on the filters using the technique described by Sanchez‐Marroquin et al (2019). The filters collected for SEM analysis had similar time resolutions to those used for INP analysis but were not measured at exactly the same time.…”

Section: Methodsmentioning

confidence: 99%

“…Using these elemental weight percentages, particles were then categorized according to their composition using a sequential algorithm in the AZtecFeature software. The software distinguished aerosol particles primarily based on their chemical composition and assigned particles to a particular category OBJ (Sanchez‐Marroquin et al, 2019) and discussed in section 3 of the SI. In this work, typically <5% of particles in each sample were not classified by the scheme and are labeled as “Others” in the results.…”

Section: Methodsmentioning

confidence: 99%

A Major Combustion Aerosol Event Had a Negligible Impact on the Atmospheric Ice‐Nucleating Particle Population

et al. 2020

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Clouds containing supercooled water are important for both climate and weather, but our knowledge of which aerosol particle types nucleate ice in these clouds is far from complete. Combustion aerosols have strong anthropogenic sources, and if these aerosol types were to nucleate ice in clouds, they might exert a climate forcing. Here, we quantified the atmospheric ice-nucleating particle (INP) concentrations during the United Kingdom's annual Bonfire Night celebrations, which are characterized by large amounts of combustion aerosol from bonfires and fireworks. We used three immersion mode techniques covering more than 6 orders of magnitude in INP concentration over the temperature range from −10°C to homogeneous freezing. We found no observable systematic change in the INP concentration on three separate nights, despite more than a factor of 10 increase in aerosol number concentrations, up to a factor of 10 increase in PM 10 concentration, and more than a factor of 100 increase in black carbon (BC) mass concentration relative to pre-event levels. This implies that BC and other combustion aerosol such as ash did not compete with the INPs present in the background air. Furthermore, the upper limit of the ice-active site surface density, n s (T), of BC generated in these events was shown to be consistent with several other recent laboratory studies, showing a very low ice-nucleating activity of BC. We conclude that combustion aerosol particles similar to those emitted on Bonfire Night are at most of secondary importance for the INP population relevant for mixed-phase clouds in typical midlatitude terrestrial locations. Plain Language Summary Liquid water droplets found in clouds can cool to well below 0°C while remaining in the liquid phase (this is known as supercooling). These supercooled droplets can remain liquid down to below around −33°C without freezing, unless there is a certain type of aerosol particle present: an ice-nucleating particle (INP). Hence, INPs have the potential to drastically change the properties and lifetime of clouds, but the sources of INP in the atmosphere are poorly defined. In this study we measured the INP concentration before, during, and after a major combustion aerosol event in the United Kingdom, Bonfire Night. This celebration is characterized by bonfires (primarily made of waste wood, but also containing garden and household waste) and fireworks. We found that aerosol particles emitted during the celebration are not as effective at nucleating ice as aerosol particle already present in the atmosphere. We conclude that aerosol particles emitted from combustion processes such as those observed on Bonfire Night are not an important source of INPs.

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“…High PM 1 concentrations were also measured during two dust storms in 2015, where the PM 1 /PM 10 mass ratios ranged from 0.34-0.63. Moreover, submicron/supermicron ratios of 0.5 were calculated from particle number concentrations measured during the flight of aircraft inside Icelandic dust storm in 2017 47 . Such high ratios are usually reported in polluted urban areas in Europe or Asia, rather than during natural dust air pollution.…”

Section: Discussionmentioning

confidence: 99%

“…A winter dust storm was measured in Iceland on 25 th February 2007, when a Passive Cavity Aerosol Spectrometer Probe (optical counter for particles of 0.1-3 μm diameter) was on board the aircraft 29 . About 100-300 particles cm −3 were measured at 400 and 700 m altitudes inside the dust plume while 10-50 particles cm −3 were measured at an altitude of 1900 m. Large particles ~20 µm were collected inside Icelandic dust storm at 320 m altitude in 2017 47 . This shows that dust events cause considerable air pollution as well as influence ice nucleation in mixed-phase clouds in the Arctic 47 .…”

Section: Discussionmentioning

confidence: 99%

Vertical distribution of aerosols in dust storms during the Arctic winter

Dagsson-Waldhauserová

Renard

Ólafsson

et al. 2020

Preprint

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High Latitude Dust (HLD) contributes 5% to the global dust budget, but HLD measurements are sparse. Iceland has the largest area of volcaniclastic sandy desert on Earth where dust is originating from volcanic, but also glaciogenic sediments. Total Icelandic desert areas cover 44,000 km2 which makes Iceland the largest Arctic as well as European desert. Icelandic volcanic dust can be transported distances > 1700 km towards the Arctic and deposited on snow, ice and sea ice. It is estimated that about 7% of Icelandic dust can reach the high Arctic (N>80&#176;). It is known that about 50% of Icelandic dust storms occurred during winter or subzero temperatures in the southern part of Iceland. The vertical distributions of dust aerosol in high atmospheric profiles during these winter storms and long-range transport of dust during polar vortex condition were unknown.Dust observations from Iceland provide dust aerosol distributions during the Arctic winter for the first time, profiling dust storms as well as clean air conditions. Five winter dust storms were captured during harsh conditions.&#160; Mean number concentrations during the non-dust flights were < 5 particles cm-3 for the particles 0.2-100 &#181;m in diameter and > 40 particles cm-3 during dust storms. A moderate dust storm with > 250 particles cm-3 (2 km altitude) was captured on 10th January 2016 as a result of sediments suspended from glacial outburst flood Skaftahlaup in 2015. Similar particle number concentrations were reported previously in the Saharan air layer. Detected particle sizes were up to 20 &#181;m close to the surface, up to 10 &#181;m at 900 m altitude, up to 5 &#181;m at 5 km altitude, and submicron at altitudes > 6 km.Dust sources in the Arctic are active during the winter and produce large amounts of particulate matter dispersed over long distances and high altitudes. HLD contributes to Arctic air pollution and has the potential to influence ice nucleation in mixed-phase clouds and Arctic amplification.&#160;Reference:Dagsson-Waldhauserova, P., Renard, J.-B., Olafsson, H., Vignelles, D., Berthet, G., Verdier, N., Duverger, V., 2019. Vertical distribution of aerosols in dust storms during the Arctic winter. Scientific Reports 6, 1-11.

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Characterisation of the filter inlet system on the BAE-146 research aircraft and its use for size resolved aerosol composition measurements

Cited by 5 publications

References 19 publications

The ice-nucleating ability of quartz immersed in water and its atmospheric importance compared to K-feldspar

The ice-nucleating ability of quartz immersed in water and its atmospheric importance compared to K-feldspar

A Major Combustion Aerosol Event Had a Negligible Impact on the Atmospheric Ice‐Nucleating Particle Population

Vertical distribution of aerosols in dust storms during the Arctic winter

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