Influence of aerosols on the life cycle of a radiation fog event. A numerical and observational study

Stolaki, S.; Haeffelin, Martial; Lac, Christine; Dupont, Jean-Charles; Elías, T.; Masson, V.

doi:10.1016/j.atmosres.2014.04.013

Cited by 62 publications

(77 citation statements)

References 57 publications

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“…According to Chen et al (2012), such large aerosols are made possible by the large hygroscopic growth factor which sharply increases with RH and can be larger than 3 at RH of 99 % for aerosols of dry diameter of 250-1000 nm. Consistently, Stolaki et al (2014) showed that the number concentration of aerosols included between 200 and 500 nm dry diameter, measured by a TSI SMPS particle counter, was of the same order of magnitude as the hydrated aerosols measured by the WELAS. Hammer et al (2014b) found a median transition diameter of 2.6 µm for the 2012-2013 ParisFog season.…”

Section: Hydrated Aerosol Sizesupporting

confidence: 61%

“…Visibility parameterizations incorporated in numerical modelling of fog usually consider only droplets (e.g. Gultepe et al, 2006;Stolaki et al, 2014). We present the consequences of not considering aerosols.…”

Section: Df20+ and Welas Welas And Mie Theorymentioning

confidence: 99%

“…Gultepe et al, 2006;Stolaki et al, 2014). However, Jiusto (1981) suggested that a significant amount of the total extinction in fog is due to hydrated aerosol particles of the accumulation mode (with diameters smaller than 2 to 4 µm), which were shown by Eldridge (1966) to be predominant in number.…”

Section: Introductionmentioning

confidence: 99%

“…RAD fogs formed as an elevated fog layer in November 2011 at SIRTA when visibility at surface level was already smaller than 5 km, after nocturnal radiative cooling. The typical case of the c4 mist-fog-mist cycle (15 November 2011) was presented in detail by Stolaki et al (2014): the fog formed at around 150 m above ground level (a.g.l. ), and in 30 min the fog base reached the surface.…”

Section: Fog Formation Typesmentioning

confidence: 99%

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Enhanced extinction of visible radiation due to hydrated aerosols in mist and fog

Elías¹,

Dupont

Hammer

et al. 2015

Atmos. Chem. Phys.

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Abstract. The study assesses the contribution of aerosols to the extinction of visible radiation in the mist-fog-mist cycle. Relative humidity is large in the mist-fog-mist cycle, and aerosols most efficient in interacting with visible radiation are hydrated and compose the accumulation mode. Measurements of the microphysical and optical properties of these hydrated aerosols with diameters larger than 0.4 µm were carried out near Paris, during November 2011, under ambient conditions. Eleven mist-fog-mist cycles were observed, with a cumulated fog duration of 96 h, and a cumulated mist-fogmist cycle duration of 240 h.In mist, aerosols grew by taking up water at relative humidities larger than 93 %, causing a visibility decrease below 5 km. While visibility decreased down from 5 to a few kilometres, the mean size of the hydrated aerosols increased, and their number concentration (N ha ) increased from approximately 160 to approximately 600 cm −3 . When fog formed, droplets became the strongest contributors to visible radiation extinction, and liquid water content (LWC) increased beyond 7 mg m −3 . Hydrated aerosols of the accumulation mode co-existed with droplets, as interstitial non-activated aerosols. Their size continued to increase, and some aerosols achieved diameters larger than 2.5 µm. The mean transition diameter between the aerosol accumulation mode and the small droplet mode was 4.0 ± 1.1 µm. N ha also increased on average by 60 % after fog formation. Consequently, the mean contribution to extinction in fog was 20 ± 15 % from hydrated aerosols smaller than 2.5 µm and 6 ± 7 % from larger aerosols. The standard deviation was large because of the large variability of N ha in fog, which could be smaller than in mist or 3 times larger.The particle extinction coefficient in fog can be computed as the sum of a droplet component and an aerosol component, which can be approximated by 3.5 N ha (N ha in cm −3 and particle extinction coefficient in Mm −1 ). We observed an influence of the main formation process on N ha , but not on the contribution to fog extinction by aerosols. Indeed, in fogs formed by stratus lowering (STL), the mean N ha was 360 ± 140 cm −3 , close to the value observed in mist, while in fogs formed by nocturnal radiative cooling (RAD) under cloud-free sky, the mean N ha was 600 ± 350 cm −3 . But because visibility (extinction) in fog was also lower (larger) in RAD than in STL fogs, the contribution by aerosols to extinction depended little on the fog formation process. Similarly, the proportion of hydrated aerosols over all aerosols (dry and hydrated) did not depend on the fog formation process.Measurements showed that visibility in RAD fogs was smaller than in STL fogs due to three factors: (1) LWC was larger in RAD than in STL fogs, (2) droplets were smaller, (3) hydrated aerosols composing the accumulation mode were more numerous.

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Section: Hydrated Aerosol Sizesupporting

confidence: 61%

Section: Df20+ and Welas Welas And Mie Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Fog Formation Typesmentioning

confidence: 99%

See 2 more Smart Citations

Enhanced extinction of visible radiation due to hydrated aerosols in mist and fog

Elías¹,

Dupont

Hammer

et al. 2015

Atmos. Chem. Phys.

Self Cite

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“…Their formation can be stimulated by the orography-in valleys, due to the exchange with the free atmosphere, temperatures can decrease easily. After sunrise, the ground slowly warms up, the temperature inversion starts vanishing and fog becomes progressively less dense [37].…”

Section: Fog Types By Dynamical Originmentioning

confidence: 99%

Fogs: Physical Basis, Characteristic Properties, and Impacts on the Environment and Human Health

Pérez-Díaz

Ivanov

Peshev

et al. 2017

Water

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This work presents a selective overview of natural fogs in terms of fog types, forms and states of occurrence, physical, micro-physical, chemical and dynamic properties, basic characterizing parameters, etc. In focus are related achievements and contributions reported mainly during the last decade and a half, as a result of both laboratory studies and field observations. Processes of homogeneous and heterogeneous nucleation are analyzed in the aspects of condensation, nuclei diversity and specifics, as related to the activation, growth and deposition of fog droplets. The effect is highlighted of the water vapor's partial pressure on the surface tension of the liquid water-air interface and the freezing point of the water droplets. Some problems and aspects of fog modeling, parameterization, and forecasting are outlined and discussed on the examples of newly developed relevant 1D/3D theoretical models. Important issues of fog impacts on the air quality, ecosystems, water basins, societal life, and human health are also addressed and discussed, particularly in cases of anthropogenically modified (chemical, radioactive, etc.) fogs. In view of reducing the possible negative effects of fogs, conclusions are drawn concerning the new demands and challenges to fog characterization imposed by the changing natural and social environment and the needs for new data on and approaches to more adequate observations of fog-related events.

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CCN activity of secondary aerosols from terpene ozonolysis under atmospheric relevant conditions

Cheng

Diao

et al. 2017

JGR Atmospheres

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Gas‐phase ozonolysis of terpenes is an important source of atmospheric secondary organic aerosol. The contribution of terpene‐derived aerosols to the atmospheric cloud condensation nucleus (CCN) burden under atmospheric conditions, however, remains highly uncertain. The results obtained in previous studies under simple laboratory conditions may not be applicable to atmospheric relevant conditions. Here we present that CCN activities of aerosols from terpene ozonolysis can be significantly affected by atmospheric relevant species that can act as stabilized Criegee intermediate (SCI) or OH scavengers. Ozonolysis reactions of α‐pinene, limonene, α‐cedrene, and α‐humulene were conducted in a 4.5 m3 collapsible fluoropolymer chamber at near‐atmospheric concentrations in the presence of different OH scavengers (cyclohexane, 2‐butanol, or CO) and SCI scavengers (CH3COOH, H2O, or SO2). The number size distribution and CCN activity of aerosol particles formed during ozonolysis were simultaneously determined. Additionally, particulate products were chemically analyzed by using a Filter Inlet for Gases and AEROsols High‐Resolution Time‐of‐Flight Chemical‐Ionization Mass Spectrometer. Results showed that aerosol CCN activity following monoterpene ozonolysis was more sensitive to the choice of OH scavengers, while that from sesquiterpene ozonolysis was significantly affected by SCI scavengers. Combined with chemical analysis results, it was concluded that the unimolecular decomposition of CIs giving hygroscopic organic products can be largely suppressed by bimolecular reactions during sesquiterpene ozonolysis but was not significantly impacted in monoterpene ozonolysis. Our study underscores the key role of CIs in the CCN activity of terpene ozonolysis‐derived aerosols. The effects of atmospheric relevant species (e.g., SO2, H2O, and CO) need to be considered when assessing the contribution of biogenic terpenes to the atmospheric CCN burden under ambient conditions.

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Influence of aerosols on the life cycle of a radiation fog event. A numerical and observational study

Cited by 62 publications

References 57 publications

Enhanced extinction of visible radiation due to hydrated aerosols in mist and fog

Enhanced extinction of visible radiation due to hydrated aerosols in mist and fog

Fogs: Physical Basis, Characteristic Properties, and Impacts on the Environment and Human Health

CCN activity of secondary aerosols from terpene ozonolysis under atmospheric relevant conditions

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